Aseptic Food Packing

Handbook of Aseptic Processing and Packaging SECOND EDITION

Handbook of Aseptic Processing and Packaging SECOND EDITION

Jairus R.D. David Ralph H. Graves Thomas Szemplenski

Boca Raton London New York

CRC Press is an imprint of the Taylor & Francis Group, an informa business

CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2013 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Version Date: 20121003 International Standard Book Number-13: 978-1-4398-0720-0 (eBook - PDF) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright. com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com

Dedication In memory of V.R. (Bob) Carlson Dr. Walter Dunkley Robert Graves David R. Dass, Priscilla Juliet Dass, and Rufus David Lynn Joel Zylstra

Contents Foreword......................................................................................................... xvii Preface................................................................................................................xix Acknowledgments...........................................................................................xxi Authors........................................................................................................... xxiii Contributing Authors.................................................................................. xxvii Chapter 1 Aseptic processing and packaging: Past, present, and future............................................................. 1 Jairus R.D. David 1.1 Framework and current state.................................................................. 1 1.2 Departures from optima and challenges.............................................. 3 1.3 Current and future opportunities for optimization............................ 4 References............................................................................................................ 8 Chapter 2 United States history and evolution........................................ 9 Ralph H. Graves 2.1 Early pioneers............................................................................................ 9 2.2 The Graves era......................................................................................... 11 2.3 Jack Stambaugh....................................................................................... 12 2.4 The first commercial aseptic plant....................................................... 13 2.5 The real fresh company......................................................................... 13 2.6 The first aseptic form–fill–seal packages............................................ 13 2.7 Early aseptic packers.............................................................................. 14 2.8 Restrictions for growth.......................................................................... 15 2.9 Trends for the future.............................................................................. 16 References.......................................................................................................... 17 Chapter 3 The U.S. markets for aseptic packaging................................ 19 Thomas Szemplenski 3.1 Development........................................................................................... 19 3.2 Aseptic metal can market...................................................................... 20 3.3 Aseptic bag-in-box.................................................................................. 21 3.4 Aseptic paperboard market.................................................................. 25 vii

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3.5 3.6 3.7

Aseptic plastic cup market.................................................................... 28 Aseptic pouch market............................................................................ 29 Aseptic plastic bottle market................................................................ 31

Chapter 4 Aseptic processing equipment and systems........................ 33 Thomas Szemplenski 4.1 Introduction............................................................................................. 33 4.2 Aseptic processing equipment............................................................. 34 4.2.1 Basic requirements of aseptic processing equipment......... 34 4.2.2 Blending vessel, balance surge, formulation of product..... 35 4.2.3 Timing pump............................................................................ 36 4.2.3.1 Pumping of foods containing particulates.......... 37 4.2.4 Heat exchangers........................................................................ 39 4.2.4.1 Heating: Sterilization of the products................... 39 4.2.4.2 Steam injection or infusion heaters....................... 39 4.2.4.3 Plate heat exchangers.............................................. 41 4.2.4.4 Tubular heat exchangers......................................... 42 4.2.4.5 Regeneration............................................................. 44 4.2.4.6 Scraped surface heat exchangers........................... 47 4.2.4.7 Ohmic heating.......................................................... 48 4.2.4.8 Microwave heating.................................................. 49 4.2.5 Continuous holding tubes....................................................... 51 4.2.6 Deaerator.................................................................................... 51 4.2.7 Controls...................................................................................... 52 4.2.8 Aseptic surge tanks, barrier seals, and automatic airoperated valves......................................................................... 54 4.2.8.1 Aseptic surge tanks................................................. 54 4.2.8.2 Barrier seals.............................................................. 55 4.2.8.3 Valves......................................................................... 55 4.2.9 Homogenizers........................................................................... 57 4.2.10 Ingredients................................................................................. 58 4.2.11 Clean-in-place (CIP).................................................................. 59 4.2.11.1 Clean-in-place solutions.......................................... 59 4.3 Plant layout considerations................................................................... 61 4.3.1 Preparation and processing equipment and systems......... 61 4.3.2 Packaging system area (bacteriological conditions)............ 61 4.4 Utilities..................................................................................................... 63 4.4.1 System sterilization water....................................................... 63 4.4.2 Preparation water..................................................................... 64 4.4.3 Heating/cooling water............................................................. 65 4.4.4 Refrigerated water.................................................................... 66 4.4.5 Steam.......................................................................................... 67 4.4.6 Air............................................................................................... 68

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Filters........................................................................................................ 69 4.5.1 Gases........................................................................................... 69 4.5.2 Liquids........................................................................................ 71 4.5.3 HEPA filters............................................................................... 71 4.5.4 General information on filtration........................................... 72 4.6 Chemicals used as sterilizing agents (equipment)............................ 72 4.6.1 Chlorine and iodine................................................................. 73 4.6.2 Oxonia........................................................................................ 74 4.6.3 Food acids.................................................................................. 74 4.6.4 Ozone.......................................................................................... 75 4.6.5 Hydrogen peroxide................................................................... 75 4.6.6 Ultraviolet.................................................................................. 75 References.......................................................................................................... 76 Chapter 5 Aseptic filling and packaging equipment............................ 77 Thomas Szemplenski 5.1 Development of aseptic packaging...................................................... 77 5.2 Dole aseptic canning system................................................................. 79 5.2.1 Can sterilizing unit.................................................................. 79 5.2.2 The filling section..................................................................... 80 5.2.3 Lid sterilizer.............................................................................. 80 5.2.4 The sealer................................................................................... 81 5.3 Aseptic bag-in-box.................................................................................. 81 5.4 Aseptic paperboard fillers..................................................................... 85 5.4.1 Tetra Pak..................................................................................... 85 5.4.2 SIG Combibloc........................................................................... 88 5.5 Aseptic plastic cups................................................................................ 88 5.5.1 Bosch and Erca.......................................................................... 88 5.5.2 OYSTAR Hassia, Erca, Gasti, and Hamba............................. 89 5.5.3 Ampack Ammann, Benco, and Metal Box............................ 89 5.6 Coffee creamers...................................................................................... 91 5.7 Aseptic pouches...................................................................................... 91 5.7.1 Bosch........................................................................................... 92 5.7.2 DuPont/Liqui-Box and Inpaco............................................... 92 5.7.3 Fres-co........................................................................................ 93 5.7.4 OYSTAR Hassia......................................................................... 93 5.7.5 Cryovac...................................................................................... 93 5.8 Aseptic plastic bottle fillers................................................................... 94 5.8.1 Ampack Ammann.................................................................... 95 5.8.2 Bosch........................................................................................... 95 5.8.3 Krones........................................................................................ 95 5.8.4 OYSTAR Hamba....................................................................... 95 5.8.5 Procomac.................................................................................... 97 5.8.6 Serac............................................................................................ 98

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Contents 5.8.7 Shibuya Kogyo.......................................................................... 99 5.8.8 Sidel/Tetra Laval....................................................................... 99 Stork........................................................................................................ 101

Chapter 6 Aseptic packaging materials and sterilants....................... 103 Robert Fox 6.1 Product requirements.......................................................................... 103 6.2 Materials................................................................................................ 103 6.2.1 Nonbarrier sheeting............................................................... 105 6.2.2 Barrier sheeting....................................................................... 105 6.3 Sterilizing Agents................................................................................. 105 6.3.1 Heat........................................................................................... 106 6.3.2 Hot water................................................................................. 106 6.3.3 Neutral aseptic system (NAS)............................................... 106 6.3.4 Chemical sterilants................................................................. 109 6.3.5 Radiation.................................................................................. 109 6.4 Packaging systems.................................................................................110 6.4.1 Dole aseptic canning...............................................................110 6.4.2 Preformed thermoformed containers...................................110 6.4.3 Form–fill–seal (FFS).................................................................110 6.5 Environmental considerations.............................................................115 Chapter 7 Aseptic bulk packaging.......................................................... 119 Thomas Szemplenski 7.1 Aseptic bag-in-box.................................................................................119 7.2 Aseptic bulk container......................................................................... 121 7.3 Aseptic bulk storage............................................................................. 122 7.4 Aseptic ocean liner transportation and storage............................... 125 Chapter 8 Regulations for aseptic processing and packaging of food.................................................................... 129 Ralph H. Graves 8.1 U.S. Food and Drug Administration requirements and approval..................................................................................... 129 8.1.1 European versus U.S. approach............................................ 129 8.1.2 U.S. Food and Drug Administration and U.S. Department of Agriculture................................... 129 8.1.3 Pasteurized milk ordinance.................................................. 130 8.1.4 State regulations..................................................................... 130 8.1.5 Hazard analysis critical control point approach................ 130 8.2 Code of Federal Regulations (CFR).................................................... 131 8.3 Low-acid food regulations and definitions...................................... 131 8.4 U.S. Food and Drug Administration: Specific concerns................. 133

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8.5 Other requirements.............................................................................. 135 References........................................................................................................ 137 Chapter 9 Validation and establishment of aseptic processing and packaging operations...................................................... 139 Jairus R.D. David and V.R. (Bob) Carlson 9.1 Some considerations............................................................................. 139 9.2 Decision process................................................................................... 140 9.3 Equipment selection............................................................................. 140 9.4 Process schematic and process and instrument diagrams (P&IDs)..................................................................................141 9.4.1 Process schematic....................................................................141 9.4.2 P&ID schematic........................................................................141 9.5 Preinstallation review.......................................................................... 142 9.5.1 Sterilization, operation, clean-in-place, and maintenance................................................................... 143 9.5.2 Interlocks.................................................................................. 144 9.5.3 Hold tube................................................................................. 144 9.5.4 Timing pump.......................................................................... 145 9.5.5 Controls.................................................................................... 145 9.6 Postinstallation review........................................................................ 146 9.7 Equipment testing and validation...................................................... 146 9.7.1 Aseptic processing system.................................................... 147 9.7.2 Aseptic surge tank.................................................................. 148 9.7.3 Aseptic packaging system..................................................... 150 9.7.3.1 Filler and filler bowl sterilization tests and sterile gas lines and fiber sterilization tests....... 150 9.7.3.2 Aseptic zone sterilization tests............................ 151 9.7.3.3 Container and lid sterilization tests.................... 152 9.7.3.4 Conveyor chain sterilization tests....................... 152 9.8 Thermal process design for products containing particles (principles applicable to homogenous fluid foods).......................... 153 9.8.1 Scraped surface heat exchangers with straight hold tubes................................................................................ 153 9.8.2 Microbiological validation.................................................... 154 9.8.2.1 Microbiological aspects......................................... 154 9.8.2.2 Quality and optimization considerations.......... 155 9.8.3 Process filing........................................................................... 155 9.9 Factors other than temperature contributing to nonsterility......... 156 9.10 Summary............................................................................................... 157 Acknowledgments.......................................................................................... 158 References........................................................................................................ 158

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Chapter 10 Aseptic processing operations.............................................. 161 Thomas Szemplenski 10.1 Introduction............................................................................................161 10.2 Presterilization of the processing system..........................................162 10.3 Loss of sterility...................................................................................... 163 10.4 Water-to-product separation............................................................... 163 10.5 Product-to-water separation................................................................ 164 10.6 Cleaning................................................................................................. 165 10.7 Control.................................................................................................... 165 Chapter 11 Thermal processing and optimization................................ 167 Jairus R.D. David 11.1 Thermal processing and optimization...............................................167 11.1.1 Introduction..............................................................................167 11.1.2 Principles of thermal process calculations..........................167 11.1.3 Thermal process design and commercial sterility............ 170 11.1.4 Economic spoilage.................................................................. 170 11.1.5 Thermal destruction of enzymes, nutrients, and quality factors.......................................................................... 171 11.1.6 Optimization of thermal processes for nutrients and quality retention..................................................................... 172 11.1.6.1 Agitated retort........................................................ 172 11.1.6.2 The “Flash 18” process.......................................... 172 11.1.6.3 Ultra-high temperature (UHT) processing and aseptic packaging........................................... 173 11.2 Comparison of conventional canning and aseptic processing and packaging of foods........................................................................174 11.2.1 ................................................................................................ Comparison of conventional canning and aseptic processing and packaging of foods......................................174 11.2.2 Some advantages of aseptic processing and packaging of foods................................................................. 175 11.2.2.1 Nutritional quality................................................. 175 11.2.2.2 Sensory quality...................................................... 175 11.2.2.3 Microwaveability................................................... 175 11.3 Comparison of processing methods.................................................. 178 11.3.1 Pasteurization.......................................................................... 178 11.3.2 Ultra-pasteurization............................................................... 179 11.3.3 Conventional canning............................................................ 179 11.3.4 Refrigerated aseptic products............................................... 180 11.3.5 Comparison of continuous processing methods based on optimization hierarchy..................................................... 180

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11.4 Definitions............................................................................................. 183 11.5 Nomenclature........................................................................................ 185 References........................................................................................................ 186 Chapter 12 Quality assurance and food protection for aseptically processed and packaged food........................... 187 Jairus R.D. David 12.1 Introduction and concepts.................................................................. 187 12.1.1 Quality control........................................................................ 188 12.1.2 Quality assurance................................................................... 188 12.2 Quality assurance for aseptically processed and packaged food..... 188 12.2.1 Preprocess assurance............................................................. 189 12.2.1.1 Raw materials......................................................... 189 12.2.2 In-process assurance.............................................................. 190 12.2.2.1 Batch preparation................................................... 190 12.2.2.2 Thermal processing operations........................... 191 12.2.2.3 Aseptic filling and packaging operations.......... 193 12.2.3 Postprocess assurance............................................................ 196 12.2.3.1 Incubated product evaluation.............................. 197 12.2.3.2 Microbiological testing for sterility and sample size consideration..................................... 197 12.2.3.3 Distribution, handling, and storage.................... 198 12.2.3.4 ASTM drop test...................................................... 198 12.2.3.5 Cumulative assurance and product release....... 199 12.3 Hazard analysis critical control point (HACCP) program............. 199 12.3.1 Principles of HACCP.............................................................. 199 12.3.2 Categories of hazards............................................................. 200 12.4 Others..................................................................................................... 200 12.4.1 Consumer complaints............................................................ 200 12.4.2 Recalls and spoilage............................................................... 201 References........................................................................................................ 201 Chapter 13 Failure mode and effect analysis, and spoilage troubleshooting........................................................................ 203 Jairus R.D. David 13.1 Failure mode and effect analysis........................................................ 203 13.2 Failure mode and effect analysis, and troubleshooting.................. 203 13.2.1 Systems analysis and bioburden.......................................... 204 13.2.1.1 Canning or retorting............................................. 204 13.2.1.2 Aseptic processing and packaging..................... 204 13.2.2 Failure modes, analysis of their effects, and controls....... 207 13.2.2.1 Type 1: Incoming raw ingredients, handling, storage, and batching............................................ 207

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13.2.2.2 Type 2: Equipment preparation and setup......... 208 13.2.2.3 Type 3: Thermal process design and delivery—Heat cycle.............................................. 209 13.2.2.4 Type 4: Thermal process design and delivery—Cool cycle............................................. 210 13.2.2.5 Type 5: Incoming packaging material and its sterilization............................................................. 210 13.2.2.6 Type 6: Aseptic zone integrity and environmental load................................................211 13.2.2.7 Type 7: Package seal integrity.............................. 213 13.2.3 Cause-and-effect relationships............................................. 213 13.2.3.1 Microbiological and package integrity testing for troubleshooting................................... 213 13.2.4 Summary..................................................................................214 13.3 Nomenclature........................................................................................ 215 Acknowledgments...........................................................................................216 References.........................................................................................................216 Chapter 14 Aseptic processing of particulate foods.............................. 217 Pablo M. Coronel, Josip Simunovic, and Kenneth R. Swartzel 14.1 Introduction........................................................................................... 217 14.2 Considerations for equipment design............................................... 221 14.2.1 Heat exchangers...................................................................... 221 14.2.2 Novel heating technologies................................................... 223 14.2.3 Transport of liquids with particulates................................. 227 14.3 Validation of aseptic processes with particulates............................ 229 14.3.1 Available technologies and alternatives for validation......233 14.3.2 Practical considerations for validation of continuous flow sterilization treatments of particulate foods based on conservatively designed fabricated carrier particles and residence time and thermosensitive implants................................................................................... 238 14.3.3 Fabricated carrier particles: Selection, design, and relevant property adjustments............................................. 238 14.3.4 Achieving conservative thermal characteristics of carrier particle enclosures..................................................... 240 14.3.5 Experimental confirmation and adjustment of conservative thermal properties.......................................... 244 14.3.6 Thermal property adjustments for advanced heating applications.............................................................................. 244 14.3.7 Tags and implants used within the carrier particle cavities for residence time and time–temperature history measurements............................................................ 249

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14.3.8 Insertion, unobstructed flow, and retrieval of fabricated tag and implant-carrying particles.................... 254 14.4 Concluding remarks............................................................................. 259 References........................................................................................................ 260 Chapter 15 Industry research and development, and management needs and challenges...................................... 263 Jairus R.D. David 15.1 Introduction........................................................................................... 263 15.2 Research and development needs and challenges.......................... 265 15.2.1 Raw product............................................................................ 265 15.2.1.1 Raw food quality.................................................... 265 15.2.1.2 Thermization.......................................................... 266 15.2.1.3 Enzyme blockers and biotechnology.................. 266 15.2.1.4 Economic spoilage and control............................ 266 15.2.2 Processing................................................................................ 267 15.2.2.1 12D “Bot Cook” for milk....................................... 267 15.2.2.2 Lethality credit for come-up time....................... 267 15.2.2.3 Control of hold time and temperature................ 268 15.2.2.4 Heat exchangers and product quality................ 269 15.2.2.5 Holding tubes......................................................... 269 15.2.2.6 Cooling cycle and leak detection......................... 271 15.2.2.7 Surge tank............................................................... 271 15.2.2.8 Aseptic processing of low-acid particulate foods........................................................................ 271 15.2.2.9 Ohmic heating........................................................ 273 15.2.2.10 Microwave heating.................................................274 15.2.2.11 Other nonthermal processes.................................274 15.2.2.12 Additive and synergistic processes......................274 15.2.3 Aseptic filling and packaging................................................274 15.2.3.1 Line speed................................................................274 15.2.3.2 At-line and on-line measurements...................... 275 15.2.3.3 Packaging issues.................................................... 275 15.2.3.4 Bulk packaging....................................................... 276 15.2.3.5 Pulsed light technology........................................ 276 15.2.3.6 Seal integrity........................................................... 277 15.2.3.7 Aseptic filler or sterile work zone integrity and validation........................................................277 15.2.3.8 Cleanup and extended run................................... 279 15.2.3.9 Defect rate or sterility assurance level (SAL)..... 279 15.2.4 Finished product and package............................................. 281 15.2.4.1 Flavor problems..................................................... 281 15.2.4.2 Gelation and other physical defects.................... 281

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15.2.4.3 Rapid microbiological methods........................... 281 15.2.4.4 Consumer education............................................. 282 15.2.4.5 “Aseptic” versus quality fresh............................. 282 15.2.4.6 Product development............................................ 283 15.3 Management and administrative challenges................................... 283 15.3.1 Capital cost.............................................................................. 283 15.3.2 Complexity.............................................................................. 283 15.3.3 Reliability................................................................................. 284 15.3.4 Repair and maintenance........................................................ 284 15.4 Future..................................................................................................... 285 15.5 Summary............................................................................................... 286 Acknowledgment............................................................................................ 287 References........................................................................................................ 287 Appendices Contract manufacturing for aseptic processing and packaging......................................................................... 289 Thomas Szemplenski Appendix A: Aseptic filler profiles.............................................................. 291 Appendix B: Aseptic contract packers in the United States..................... 349

Foreword This book is a good resource for people who currently aseptically package and process foods, as well as for people who might wish to get involved in aseptic packaging and processing of foods. The book is based upon the extensive experience and knowledge of the authors in the aseptic food processing and equipment industry. The authors have a wide range of experience encompassing production, quality assurance, research and development, and sales in the aseptic packaging and processing industries. The information provided is very practical and can be used as a guide to develop or review current day-to-day procedures for a number of different aseptic processing and packaging applications. This book is an updated and reorganized version of the previous book Aseptic Processing and Packaging of Food: A Food Industry Perspective (CRC Press, 1996). Chapters on aseptic packaging materials and sterilants, aseptic bulk packaging, aseptic processing operations, failure mode effect analysis and spoilage troubleshooting, aseptic processing of particulate foods, and contract manufacturing have been added. These chapters encompass current information and practical applications so that those in need have a valuable useful resource. The appendices have a list of aseptic packaging equipment including those currently accepted by the U.S. Food and Drug Administration (FDA) and a list of manufacturers that do contract packaging. The chapter on aseptic packaging of particulate foods (Chapter 14) has current information on the use of microwave to heat particulate foods as well as the most recent technology available to monitor and develop processes for this special category of foods. Chapter 13 on failure mode analysis provides some examples of failure modes and their effects on food safety. Chapter 10 on aseptic processing operations discusses the totality of the operation including the processing of the product, including the operation of the aseptic packaging system. Chapter 7 on aseptic bulk packaging, provides not only a historical perspective but also an update on the state of bulk packaging in container sizes of several gallons to several millions of gallons of product. The chapter on aseptic packaging materials and sterilants xvii

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(Chapter 6) consolidates information on these subjects into one chapter and provides up-to-date information. This book is simple to use and understand with clear chapter headings. The chapters are well organized and follow a logical sequence so that topics are easy to locate. Once found, the information is understandable and can be put to immediate use. The information is current to the time (2012) it was written and has been provided from the perspective of individuals with experience in the subject. The book provides an excellent update on the status of aseptic processing and packaging and deserves a space in the library of anyone with an interest in aseptic processing and packaging of foods. Keith A. Ito Laboratory for Research in Food Preservation Food Science and Technology University of California, Davis

Preface This book provides a comprehensive treatment of aseptic processing and packaging for people interested in the food and beverage processing industry. It is based primarily on the extensive experience of the authors in processing, marketing, business, quality assurance, and research and development related to aseptically processed and packaged foods and beverages. There have been dynamic changes that have occurred in the food industry since the publication of our previous book in 1996 (David, Graves, and Carlson). Our objective was to assemble in one volume the large amount of information that has been published and to update changes in food packaging, especially aseptic filling into plastic bottles, one of the fastest growing areas in the retail sector, and bulk packaging of value-added commodity products such as juice, concentrate, and puree. Opportunities for the application of existing and novel food processing methods and sensor technologies are also discussed in various chapters. The three coauthors and the contributing authors have more than 150 years of combined food industry experience in aseptic processing and packaging of foods, which is reflected in the 15 chapters and appendices. We realize that there may be some duplication and overlap between chapters but we think that readers can read and analyze specific chapters, and obtain the information desired rather than having to read the entire book. For many years, researchers recognized that the use of high temperatures for short times had potential advantages over conventional thermal processes at lower temperatures for longer times, but there were difficulties in taking advantage of this information. Heat causes reactions in food, some of which are undesirable; the rate of reaction approximately doubles for every increase in temperature of 10C° (18F°). In contrast, typical rates of destruction of bacteria and spores increase tenfold for the same temperature increase. Therefore, processes using higher temperatures for shorter times can achieve commercial sterility with improvements in quality with respect to flavor, color, vitamin retention, and physical properties, as compared to the quality of products from conventional heat processes. Application of this principle was limited by the availability of processes and equipment to apply it in commercial practice. Rapid heat transfer for xix

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heating and cooling is readily achieved in liquid foods but not in solid foods, which depends on conduction heat transfer rather than convection. Therefore, early work focused on liquid foods, especially milk and its products. Specialized equipment was developed for applying ultra-high temperature (UHT) treatments using tubular or other heat exchangers, or steam injection or infusion devices, which were usually coupled with vacuum coolers. Commercial use of such equipment necessitated aseptic packaging after sterilization, which proved to be the most serious limitation. Early successes with milk and its products increased interest in adapting aseptic processing and packaging to other liquid foods. The book outlines progress with products such as soups, juices, and purees, and current research and development directed toward the challenging problems with foods containing solid particles. Introduction of new aseptic processing and packaging technologies necessitated the evolution of a new body of food laws and regulations, and new or expanded agencies to enforce them. Innovations in the United States have been delayed by the industry’s justifiable cautious approach in developing validation procedures for compliance with its own quality and safety standards, and those of regulatory agencies. Collaboration among industry, industry organizations, public officials, and agencies has been excellent in guiding the development of a rapidly expanding industry based on aseptic processing and packaging. The organization of the book permits readers to selectively choose those sections in which they have the greatest interest. The sections written by the different authors reflect their personal styles and areas of expertise. The book provides a comprehensive update on this rapidly developing technology for the food processing industry. We wish to express our sincere appreciation to the four contributing authors Dr. Robert Fox, Dr. Pablo Coronel, Dr. Josip Simunovic, and Dr. Kenneth Swartzel, who, by giving freely of their expertise, have made this book possible. Many thanks are due to Steve Zollo, senior editor, Taylor & Francis/CRC Press, Boca Raton, Florida, for his professionalism and unstinting support in bringing this book to publication. Our appreciation to David Fausel and Linda Leggio at Taylor & Francis/CRC Press for expediting the final stage of printing. Jairus R.D. David Omaha, Nebraska Ralph H. Graves Visalia, California Thomas Szemplenski San Diego, California Note: References to commercial products and trade names are made with the understanding that no discrimination and/or no endorsement by the authors or the organizations that they are involved with are implied.

Acknowledgments I would like to express my thanks to the following: my wife, Shelley, for her loving encouragement of this work, and to our children, Adriana, Brennan, and Blake, for “daring” me to write “another book.” Dr. Al Bolles, Senior Executive Vice President of Research, Quality, and Innovation (RQI), and Dr. Corey Berends, Vice President, Innovation, RQI, for their visionary leadership and encouragement of this work. Dr. Richard McArdle, Vice President, RQI, for espousing the value of “Leader Level 5,” and active listening. Dr. Athula Ekanayake, Research Fellow, at the Procter & Gamble Company, for introducing me to the Minto pyramid principle and logic, and to the world of natural antimicrobials and delivery systems. Dr. Kailash Purohit, President and CEO of Process Tek, Prospect Heights, Illinois, who single-handedly coined and articulated the terms “aseptic sterile work zone,” “maintenance sterility,” and “passive or dynamic decontamination” in both the pharmaceutical and food industries. His review of Chapters 9, 11, 12, 13, and 15, and useful discussions are acknowledged. Jairus R.D. David My family for their constructive criticism. Jody and Robert Graves for their good memories and expertise. My fellow authors—Jairus David and Thomas Szemplenski. Ralph H. Graves I would like to express my special appreciation to the following people: Dr. Philip Nelson of Purdue University for giving me the opportunity to participate in the development of aseptic bag-in-box and bulk storage, and his mentoring over the course of my career. Dr. Dilip Chandarana for being a very special friend and source of aseptic and other food technology over the years. xxi

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Darryl Wernimont, Director of the Haskell Co., for his longtime friendship. Malcom Knight, Vice President of Pom Wonderful, for his support of me to facilitate his company’s aseptic processing and packaging objectives, and experience hands-on installation of an aseptic rotary bottle filler. Thomas Szemplenski

Authors Jairus R.D. David, M.Sc., Ph.D., is Senior Principal Research Scientist, Innovation—Breakthrough Science, Research, Quality, and Innovation (RQI), ConAgra Foods headquartered in Omaha, Nebraska. David’s responsibilities include science leadership and development of intervention technologies for food protection, and process and quality optimization. David is a Fellow of the Institute of Food Technologists (IFT), 2008, and is the recipient of IFT’s prestigious Industrial Scientist Award, 2006. He is recognized for developing and influencing public health food safety policy on the use of honey in cereals and bakery products for the prevention of infant botulism in infants under 12 months of age. Currently, all honey and honey-containing food products in commerce carry a warning label “Do not feed honey to infants less than one year of age.” David has 20-plus years of food industry management and leadership experience in the areas of food safety, thermal processing, aseptic technology, quality assurance, and risk analysis. Prior to this, he worked at Real Fresh Aseptic Operations in Visalia, California, and Gerber Baby Foods in Fremont, Michigan. David earned his Ph.D. in microbiology with emphasis in thermal processing from the University of California at Davis, under the tutelage of Dr. Richard Larry Merson. He is a Certified Quality Manager (CQM) and Certified Quality Engineer (CQE), American Society for Quality. David has participated in the leadership development program at the Kellogg School of Management, Dr. Stephen Covey Leadership Center, Massachusetts Institute of Technology, and Center for Creative Leadership. Ralph H. Graves held the position of Senior Vice President for Real Fresh, Inc., a company involved in the processing and sale of aseptically packaged foods. His responsibilities included the research and development of processing techniques, quality control, engineering, and maintenance and warehousing of aseptically packaged dairy products. Prior to his employment with Real Fresh, Graves was involved in the startup of several xxiii

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ultra-high temperature (UHT) milk processing plants for International Milk Processors, Inc., one of the first U.S. companies devoted entirely to aseptic packaging. He majored in animal science and dairy production at Valparaiso and Michigan State universities. His interest in aseptic packaging came from his father, who was one of the pioneers in the field of UHT sterilization, holding several patents related to the process. Graves’ career has taken him around the world, from working as President of Graves Farm, Inc., in Maryland, to overseeing the production and distribution of aseptically packaged foods overseas. Milestones include assisting in the startup of a joint venture between Real Fresh and the Murray Goldburn Dairy Cooperative in Australia, and overseeing the distribution of Real Fresh milk for the first Saudi Arabian school lunch program. Although now officially retired, he continues his work in this field as a consultant for Real Fresh and other firms. Graves’ involvement in professional organizations includes: Chair of the Aseptic Packaging Committee of the National Food Processors Association (now Grocery Manufacturers Association [GMA]); Past President of the California Creamery Operators Association; Director and Secretary–Treasurer of the California Dairy Institute; member of the Scientific Affairs Committee of the National Food Processors Association; President of Visalia Kiwanis Club; President of California Backcountry Horsemen; and Treasurer and Director of Visalia, California Chamber of Commerce. Thomas Szemplenski is currently the owner of Aseptic Resources, Inc., a consulting company dedicated to assisting food processors and equipment manufacturers with aseptic processing techniques. He has more than four decades of food processing and packaging experience. The vast majority of those years have been dedicated to aseptic processing and packaging techniques, commercial application, and marketplace dynamics. Prior to starting Aseptic Resources in 1987, Szemplenski initially worked for a frozen food manufacturer and after attending the University of Nebraska, he went on to hold senior marketing positions with several leading manufacturers of food processing equipment, affording worldwide exposure to many different aseptic processing and packaging alternatives. In addition, while in these marketing positions, Szemplenski was very fortunate to work and learn from Dr. Phil Nelson of Purdue University and William Scholle with the initial development of aseptic packaging of food products into bag-in-box. Subsequently, he has actively participated in many commercial aseptic processing and packaging systems using bag-in-box fillers.

Authors

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A number of years ago, while continuing Aseptic Resources, Szemplenski concurrently was a part owner of an aseptic processing facility located in the Midwest. This facility aseptically contract packaged both high- and low-acid food products under FDA validation. Szemplenski has published numerous papers during his professional career primarily dealing with aseptic processing and packaging techniques, and he has been invited to teach aseptic processing techniques at several leading universities and major food processors. Additionally, Szemplenski holds several patents centered on aseptic technology.

Contributing Authors Pablo M. Coronel, Ph.D. R&D Aseptia, Inc. Raleigh, North Carolina Robert Fox, Ph.D. Synergy Packaging, LLC Williamsburg, Virginia

Josip Simunovic, Ph.D. Department of Food Bioprocessing   and Nutrition Sciences North Carolina State University at   Raleigh Raleigh, North Carolina Kenneth R. Swartzel, Ph.D. William Neal Reynolds   Distinguished Professor Emeritus North Carolina State University at   Raleigh Raleigh, North Carolina

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chapter 1

Aseptic processing and packaging: Past, present, and future Jairus R.D. David Marketing, industrial, and regulatory frameworks based on principles of aseptic processing and packaging are available, and continue to be of interest to the food processors of ambient, shelf-stable foods in retail packages and bulk containers. Aseptic processing and packaging of foods consist of filling sterilized and cooled food into presterilized containers, followed by hermetic sealing with a presterilized closure in a presterilized and continuously decontaminated tunnel or aseptic work zone. It is axiomatic to consider aseptic processing and packaging as the benchmark in optimization, for manufacture of sterile, shelf-stable canned food. Contrasted with retorting or in-container sterilization, in aseptic processing, the product and package are independently sterilized by optimal processes, wherein microbial inactivation and quality factor degradation are also co-optimized given first-order kinetics. Aseptic systems permit sterilizing the product and container separately and appropriately, without the rate-limiting heat transfer modes, or the attendant thermal and pressure stress to the container closure and seal integrity, and permitting high-temperature, short-time (HTST) or ultra-high temperature (UHT) processing of very heat-labile products without excessive quality and nutritional degradation, while achieving requisite commercial sterility (see Figure 1.1).

1.1  Framework and current state Aseptic processing is a commercially successful and robust technology. It is approximately 70 years old, and began with the invention of the first aseptic line of the Heat/hold–Fill/hold–Cool (HFC) system by Dr. C. Olin Ball (1936). Aseptic technology became a commercial reality with the installation of Dr. W.M. Martin’s Dole (1951) aseptic canner in the 1950s. 1

2

Raw Product

Handbook of aseptic processing and packaging

UHT Bulk Sterilize

Bulk Cool

Aseptic Balance Tank

Aseptic Product Filler and Packaging * Sterile work zone * Package and seal integrity * Interfaces

Commercially Sterile ShelfStable Filled Containers

Figure 1.1  A schematic diagram of an ultra-high temperature (UHT) processing and aseptic filling and packaging system.

Martin recognized that the production of nutritionally superior and “home-style” baby foods, heat-sensitive infant formula, and milk products would be possible through the use of short-time, high-temperature sterilization together with aseptic canning. In the United States before 1981, the Martin–Dole aseptic canning system was the only aseptic filling and packaging system of commercial importance for milk and milk-based low-acid products in metal cans. This core technology was correctly designated as UHT-sterilized and aseptically packaged process. The pre-1981 market drivers were better quality, low-acid, heat-sensitive products, compared to retorted versions. It was a formidable marketing and research and development challenge to educate consumers to appreciate aseptic technology and differentiate products in Martin–Dole aseptic metal containers from that of classical canning or retorting. Also in commercial use were 55-gallon metal drums invented in the 1970s by Fran Rica for bulk packaging of tomato products. In 1981, the U.S. Food and Drug Administration (FDA) approval of the food additive petition for use of hydrogen peroxide as a sterilant for food contact surfaces provided the impetus for introduction of various aseptic filling and packaging systems into the U.S. markets. The market was primarily driven by “juice box” technology, which involved high-acid food pasteurization at HTST followed by aseptic filling and packaging. The post1981 market drivers were use of alternate flexible and semirigid packages, consumer convenience, reduced package weight, cost reduction, superior quality and nutrition, and package sterilization by optimal methods. Aseptic processing and packaging is one of the most dynamic and profitable sectors in the U.S. food and beverage market. The major aseptic packaging segments are cans, plastic bottles, plastic cups, bag-in-box, paper board, and pouches. In addition, the aseptic processing industry is going through another period of specific growth via plastic, primarily polyethylene and polyethylene terepthalate (PET) containers to the world market. These packages have been in commercial use for several years for packaging high-acid products (such as fruit juices and spaghetti sauces) and refrigerated low-acid products (such as fruit smoothies, and white and flavored milk beverages), but are being used with increasing frequency for low-acid shelf-stable fluid products (such as coffee and protein-fortified nutritional beverages, and energy and sports drinks) to

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meet consumers’ modern lifestyle and demand for ergonomic and environmentally sustainable containers. Today, there are more than 34 manufacturers of aseptic filling equipment worldwide (Appendix A) and more than 600 aseptic systems for manufacture of retail package and bulk containers in the United States. Contract manufacturers play a crucial role in the introduction of innovative and consumer-convenient new products to the market in a timely and cost-effective manner (Appendix B). Contract manufacturers facilitate rapid prototyping, product sensory and specifications development, and go/no-go business decisions.

1.2  Departures from optima and challenges Even though the aseptic technology is considered the benchmark in optimization for manufacture of sterile, shelf-stable canned food, there are several departures from optima or gaps that should be closed in order to leverage the full benefits of quality, nutrition, safety, and convenience. Some of the gaps include potential compromises to sterile work zone and seal integrity leading to microbial recontamination, overdelivery of designed thermal process, inadequate or slow cooling, and special handling of sensitive ingredients known to contain and protect thermoduric and thermophilic spores during heating. Aseptic systems that process and package shelf-stable foods are indeed well suited to be hierarchically co-optimized, as there are many competing priorities and numerous critical parameters that must be validated and controlled. But most important, the numerous vectors of recontamination must be recognized for their capacity to cause failure. Although sophisticated control systems do help, there is no substitute for training, environmental control, and system validation for defect prevention and food protection. The aseptic zone is undoubtedly the heart of the aseptic system and is crucial to the delivery of a sterile product. Although it can be presterilized and validated to be sterile to a sterility assurance level of 10−6, procedures and practices to maintain or monitor its sterility are unavailable. It is assumed to be sterile by virtue of presterilization and the use of sterile, high-efficiency particulate air (HEPA), or laminar flow air. Thus the work zone is at best, sterile or passive, and not sterilizing or active, and thus not able to overcome recontamination. The vectors of recontamination include filter failures, grow through, and nonsterile air aspiration by the work zone due to loss of laminarity, eddy currents at interfaces or leaks, and the discharge of finished containers from the zone (K. Purohit, Process Tek, personal communication, 2008). It should be reemphasized that despite subsystem validation to 10−6, overall sterility assurance is governed by the aseptic work zone, wherein

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maintenance of sterility cannot be assured and monitored, and any recontamination cannot be detected, removed, or inactivated. An exception is the active or sterilizing work zone (using superheated steam), which is an integral part of the very first aseptic system—the Martin–Dole aseptic canner. However, it is important to note that the Dole aseptic system is somewhat vulnerable, when superheated cans are “tempered down” prior to filling to avoid product contact burn-on. The terminal retort process in canning is a de facto seal integrity tester, and marginal seals usually do not survive the time, temperature, and pressure of the retort scheduled process. In aseptics, not only are the product and package decoupled but also the final seal, made in a sterile work zone, is not trauma tested, ever. In aseptics, the reliability of seal inspections, mandatory incubation holds, and sterility tests take on additional significance. Thus, seal integrity and maintenance of hermeticity in aseptics is a key determinant of sterility assurance. Precise control of flow and temperature are essential for proper design and delivery of an approved thermal process, followed by prompt cooling. Inability to control temperatures within 5°F in the UHT regime can lead to irreversible damage, because this may correspond to a doubling or tripling of process lethality (Fo). The food industry should strive for defining the safety and quality and biofunctionality limits in a scheduled process to prevent departure from process optimum.

1.3 Current and future opportunities for optimization The future of aseptic processing will depend upon reducing the departures from process optima, and capturing findings from ongoing research in both basic and applied research leading to the use of both novel thermal sterilization methods coupled with innovative nonthermal processes, sensors, and nanotechnologies. It is important to underscore that no one single technology can replace the shelf-stable capabilities of either classical retorting or aseptic processing. However, many of the innovative thermal and nonthermal processes, sensor, and nanotechnologies can be used either additively or synergistically to build “hurdles” in tandem with an objective to produce superior products with minimal heat-induced damage and at an affordable price (see Figure 1.2 and Chapter 15). Developments on the filling and packaging side of the aseptic technology will continue to be the major driving force in the further expansion of this technology. Emerging package and packaging material sterilization processes like plasma generation and glass lining will expand the number and variety of polymers in use for aseptic packaging as well as available package shapes and sizes (Sandeep et al. 2004).

Pasteurization

ESL Pasteurization

Aseptic Processing

Optimization and Business Opportunities

Optimized Aseptic Processing Continuum

Other Thermal and Nonthermal Processes, Sensor, and Nanotechnologies

Figure 1.2  A schematic diagram of an ultra-high temperature (UHT) processing and aseptic filling and packaging system— optimization continuum. (ESL: extended shelf life.)

Chapter 1:  Aseptic processing and packaging: Past, present, and future

Canning

5

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Larger (institutional and industrial ingredient) sizes of aseptically packaged products currently have the most favorable (low) ratio of packaging material used per unit of product weight and volume, and this advantage will continue to grow, especially for products yet to make a significant impact in the aseptic processing area, such as low-acid particulate products. There is the need to avoid re- or double-processing of previously bulk processed aseptic high value-added commodity products (orange juice, purees of banana, prunes, and other exotic berries) via development of reliable proper transfer fitment and techniques for ambient repackaging into retail-sized containers. Uniform quality, reduced need for frozen and refrigerated distribution and storage as well as progressively more favorable ratios of packaging material used per unit product will positively impact the environmental and economic advantage of this technology over currently dominant conventional technologies. Developments in conventional tube-in-tube heat exchanger design will also continue. Helical, dimpled, corrugated, and agitated heat exchangers will be introduced in commercial production with increasing frequency. Emerging thermal processing technologies, specifically volumetric heating methods like continuous flow microwave heating (microwave-assisted thermal sterilization [MATS], North Carolina State University and Washington State University), radio frequency, and ohmic/electric resistance heating will have a major impact on quality and variety of available aseptic food products in the near future. Applications of emerging nonthermal and thermally assisted technologies like ultrahigh pressure processing (pressure-assisted thermal sterilization [PATS], Institute of Food Safety & Health [IFSH]), pulsed electric field treatments, irradiation, sonication, thermosonication, and manothermosonication will expand and integrate with other aseptic processing operations in single and multiple concurrent and sequential bactericidal treatment to achieve extended refrigerated shelf life and shelf stability. Incremental adjustments will be made to all processing stages and equipment to accommodate multiphase products, especially low-acid products containing large particulate components. Particle-compatible pumps, heat exchangers, tanks, back pressure valves, filler heads, and package transfer fitments will continue to be improved and integrated into aseptic production lines. Improper removal of heat from bulk sterilized foods can lead to continual degradation of quality, and nutritional and functional loss. Prompt cooling and an adequate cooling rate is integral to aseptic processing. Emerging cooling methods will be introduced and integrated into aseptic processes over an extended period of time. Evaporative, cryogenic, reverse thermocouple/peltier cooling, and newer volumetric cooling technologies

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such as magnetic field cooling and ultrasonic cooling will have an impact on quality and economy of aseptic product processing. Spore-sensitive ingredients of concern are cocoa, tapioca granules, nonfat dry milk (NFDM), carboxymethylcellulose (CMC), starches, sugar, corn, mushrooms, and spices. It is a good practice to monitor, measure, track, and control the mesophilic and thermophilic spore loads of each batch of raw product based on ingredients in a formulation. In addition, these ingredients must be completely hydrated prior to batching to ensure that any spores (if and when present) are fully exposed to a designed and delivered thermal process via a direct or indirect method of heating for prevention of economic spoilage. The concept of cold, in-line sterile formulation, wherein one or more HTST/UHT sterile streams are operated in tandem with one or more filter sterilized streams into aseptic surge tank, filler bowl, or sterile container is sometimes utilized for very heat-sensitive ingredients or components. Some very heat-labile products are exclusively filter sterilized and aseptically filled and sealed with no heat trauma at all. The availability of a wide array of membrane, ceramic, and sintered metal filters are making this process option more commonplace, as do a few process, validation, and production safety concerns. New techniques of real time and postprocess measurement and monitoring will be implemented to accurately and reliably monitor and quantify all lethality delivered to all segments of an aseptic processing system. These emerging techniques and tools will take advantage of miniaturization of sensing elements and nanotechnology level development currently taking place in other areas of research and development. Unavailability or inconsistent application of process establishment, monitoring, and validation tools have been one of the most significant hurdles in expanding the range of aseptic processing of more difficult, particularly multiphase food products (K.R. Swartzel, North Carolina State University, personal communication, 2011; see Chapter 14). As the locus of research and development and commercialization of aseptics moves toward large particulates, sterile formulation, higher throughputs, and extended production runs (120 hours) for better overall equipment effectiveness (OEE), the demands for control and monitoring will no doubt increase. Maintenance of sterility and prevention of recontamination are the aseptic equivalents of postprocess contamination (historically the canning industry’s Achilles’ heel), except that in aseptics they are so intertwined with the system’s design and operation that they will require constant, significant, and specialized attention including preventive maintenance, breakdown maintenance, and intermittent cleanup and clean-in-place (CIP) to keep aseptic systems acceptable from public safety concerns (K. Purohit, Process Tek, personal communication, 2008).

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There is the need to develop sensitive, reliable, and cost-effective nondestructive at-line package integrity tests compatible with current and future line speeds. Troubleshooting of microbial spoilage problems often can be resolved using known problem solving tools including Six Sigma. Further identification and speciation via modern molecular methods is needed for proper root cause analysis (RCA) and definitive corrective action and preventive action (CAPA). Tracking sources of microbial contaminants has been a concern, given the uncertainties associated with the integrity and maintenance decontamination of the “sterile working zone” or the aseptic tunnel during normative and extended production runs up to 120 hours. However, recent advances in the development of molecular subtyping methods have provided tools that allow more rapid and highly accurate determinations of these sources (J. Kornacki, Kornacki Microbiology Solutions, Inc., personal communication, 2011). Sometimes spoilage problems due to compromises in the aseptic sterile zone cannot be resolved by traditional RCA leading to meaningful CAPA. In such cases, advanced problem solving tools such as TRIZ (theory of inventive problem solving, developed by Genrich Altshuller) should be deployed (Cameron 2010). Aseptic processing and packaging is an attractive and a challenging alternative compared to conventional methods of canning of foods. New aseptic facilities are continuing to be constructed around the world. Continuous sterilization of heat-sensitive foods at ultra-high temperatures, followed by prompt cooling results in a superior finished product, which can be filled into containers of varying compositions, of different shapes, and with many consumer-attractive features. Compared to classical canning, the definitive market advantage of aseptically processed and packaged foods originates from the ability to incorporate several valueadded features, such as substantially increased sensory and nutritional qualities, microwaveability, several user-friendly conveniences, and cost saving from use of plastics.

References Ball, Charles Olin. 1936. Apparatus for and a method of canning. U.S. Patent 2,029,303, issued February 4, 1936. Cameron, G. 2010. TRIZICS—Teach Yourself TRIZ. Lexington, KY: Createspace Printers. Martin, William McKinley. 1951. Apparatus and method for preserving products in sealed containers. U.S. Patent 2,549,216, issued April 17, 1951. Sandeep, K.P., Simunovic, J., and Swartzel, K.R. 2004. Developments in aseptic processing. In Improving the Thermal Processing of Foods, edited by Philip Richardson. Boca Raton, FL: CRC Press.

chapter 2

United States history and evolution Ralph H. Graves

2.1  Early pioneers C. Olin Ball (Figure 2.1) is credited with being the earliest pioneer in the development of aseptic processing and packaging in the United States. His research in conjunction with the American Can Research Department in 1927 led to the development of the Heat/hold–Fill/hold–Cool (HCF) process. The processes received its name from the first letters of the words heat, cool, and fill. Numerous pilot tests were run on many different products. In 1938, two HCF units were installed for commercial production of a chocolate milk beverage. The HCF process did not expand beyond these two commercial lines, and these lines are no longer in operation. Although the HCF process was not a commercial success, it was a great success in that it was the initiator of all the work that followed. In 1942, at the Avoset plant in Gustine, California, George Grindrod developed the Avoset process. Whipping cream was sterilized by steam injection and packaged in cans, and later in glass bottles. Containers were sterilized in retorts using saturated steam. The retort method of sterilization was eventually abandoned and replaced by a continuous hot-air system and utilized ultraviolet lamps to protect the filling and closing area. Like the HCF process, the Avoset process is no longer in operation, but it served as a stepping stone in the evolution of aseptic processing and packaging technology. In 1948, William McKinley Martin (Figure 2.2) entered the arena with the Dole aseptic process. The Dole aseptic process involved four separate operations: (1) sterilization of the product in a tubular heat exchanger system; (2) sterilization of the containers and covers with superheated steam; (3) aseptic filling of the cooled sterile product into the sterile containers; and (4) sealing the lids in an atmosphere of superheated steam. Martin’s aseptic canner overcame many of the obstacles that prevented wider application of the HCF unit. The use of superheated steam at atmospheric 9

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Handbook of aseptic processing and packaging

Figure 2.1  C. Olin Ball.

pressure eliminated the need for rotary valves for passing empty cans into the system and finished cans out of the system. Also, the use of atmospheric pressure negated the need for construction of high-pressure equipment. This early unit was the forerunner of the Dole aseptic canner. Dole aseptic canners are still in use today. The first commercial units were installed in 1951 for Andersen Pea Soup and sterilized milk at the Med-O-Milk plant in East Stanwood, Washington.

Figure 2.2  William McKinley Martin.

Chapter 2:  United States history and evolution

11

2.2  The Graves era Roy Graves (Figure  2.3) had a restless mind. He was a creative genius that could have used a full-time staff to follow him around and pick up on his pearls of wisdom. A brief look at his accomplishments over a span of 70 years in the dairy industry is impressive. After completing graduate work at the University of Missouri in 1912, he became the head of the fledgling Dairy Department at Oregon State College at Corvalis, Oregon. After World War II, he became part of the U.S. Department of Agriculture’s (USDA) Food for Peace Program, which encouraged new food sources. Graves joined the Bureau of Dairy Services, USDA, rising to become chief of the Division of Cattle Breeding, Feeding, and Management. His duties included overseeing the extensive research programs at its Beltsville, Maryland, facility. He was the author of over 100 scientific papers and bulletins, and acted in an advisory capacity to several university and

Figure 2.3  “Pea Soup” Andersen in front of a Martin aseptic filler, which made perfect soup possible.

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college dairy departments. In 1931, he served as the U.S. delegate to the World’s Dairy Congress in Copenhagen. From 1935 to 1939, he was secretary-treasurer of the American Dairy Science Association and served as its president in 1937. He patented the combine-pipeline milking machine along with the merry-go-round milking platform called the Rotolactor. The first unit was installed at the Walker Gordon Dairy in New Jersey and later became a live display at the 1939 World’s Fair in New York. Subsequently, these patents were acquired by De Laval Ltd., which continues to manufacture and market adaptations of the original combine milking machine. In the 1940s Graves began work with other scientists on sterilizing milk. They reasoned that fresh milk could be drawn from the cow without it being exposed to the air, sterilized and packaged aseptically, and retain its natural quality and nutrition. His patent-owning company, Graves– Stambaugh, Inc., obtained the patents that were put to commercial test by Real Fresh, Inc., and several other licensees. The original patents described a method whereby milk was transferred from the cow via a pipeline to a vacuum tank mounted on wheels. The vacuum tank was then transported to the dairy plant; the milk was removed by pump, heat treated to 285°F, cooled immediately to room temperature, and packaged aseptically into metal cans. The product found immediate acceptance by the U.S. military, diplomatic, and commercial personnel living around the world with no access to fresh milk. Graves actively continued improving his original ideas up to his death in 1976 at the age of 90. The patents have expired, and the vacuum tanks retired, but the understanding of the need for high-quality raw milk remains a top priority for all ultra-high temperature (UHT) processing and aseptic packaging plants.

2.3  Jack Stambaugh Jack Stambaugh, Graves’ patent coholder, was the owner of Wood Jon Farms and the dairy in Valparaiso, Indiana, where the original research work was performed from 1946 to 1950. The friendship between Stambaugh and Graves began in Washington, DC, during World War II. Stambaugh, an army officer, was assigned to the USDA to oversee a program to increase dairy foods production. Motivated by an interest in purebred Holstein dairy cattle, he looked to Graves for advice. Graves in turn found a willing and eager ear for his ideas on the genetics of dairy cattle, methods for preserving green roughage, loose housing, milking parlors, and on to UHT processing. This dialogue included discussions on a new type of heat exchanger Graves had designed for UHT processing and a method for aseptically packaging milk so it did not need refrigeration to extend its shelf life.

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When Graves retired from the USDA in 1945, he moved his own herd of purebred Holsteins to Indiana and joined in a partnership with Stambaugh. They enlisted help from the Continental Can Company, which provided financial and technical expertise from its Chicago research center. Together they shared a vision for the future of the dairy industry.

2.4  The first commercial aseptic plant The first commercial plant to use the Graves–Stambaugh process was built in 1951 at East Stanwood, Washington. Their brand name was MedO-Milk. One of the first Martin (later became Dole) aseptic canning machines was purchased and installed there to carry out the aseptic packaging part of the process. The initial market was Alaska, because most of its milk supplies had to be imported from the lower 48 states. Two other licensees quickly followed: one in Visalia, California, using the brand name Real Fresh, and the other, the International Milk Processors, Inc., plant in Ridgeland, Wisconsin.

2.5  The real fresh company In 1952, utilizing the Graves–Stambaugh patents, Robert Graves, Roy Graves’ son, opened the new Real Fresh Milk, Inc., in Visalia, California. Though largely unnoticed by the rest of the dairy industry, it was a truly unique facility as it was the second American dairy plant, in one year, dedicated solely to sterilizing milk at ultra-high temperatures and packaging aseptically.

2.6  The first aseptic form–fill–seal packages In 1959, work was underway at Real Fresh to move beyond metal cans into paper–foil–plastic laminated packages. It began with the conversion of the Tetra Pak tetrahedron filler of pasteurized dairy products into an aseptic unit. In 1962 Roy Graves’ patent-owning company received patent numbers 3,063,845 and 3,063,211 on this chemically sterilized aseptic packaging system using chlorine as the web sterilant. The tetrahedron package, however, was never widely accepted by the American consumer, but large quantities were produced for the U.S. Navy during the Korean conflict. In 1981, Tetra Pak returned to the United States and introduced the Brik Pak carton. The system used hydrogen peroxide as a sterilant on the form-fill container and was approved by the U.S. Food and Drug Administration (FDA) in January 1981. Real Fresh commissioned and operated the first commercial Brik Pak filler in the United States, in partnership with the National Food Processors Association (NFPA) and Tetra Pak Company.

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The Graves–Stambaugh heat exchangers were used at Real Fresh for over 20 years, when they were replaced by steam injection-direct heating systems and a new state-of-the-art tubular/indirect heating processor. Graves believed that enzyme reactivation and oxidative deterioration due to exposure to air, along with the reaction from certain strains of bacteria, were the prime culprits in preventing preservation of unrefrigerated milk for extended periods of time. His patents and subsequent research were devoted to correcting those problems and were instrumental in bringing many new aseptically packaged products to market. To name a few: infant formula, flavored milks, sour cream, cheese spreads and sauces, hollandaise sauce, a dairy spread (butter substitute), eggnog, ice cream and ice milk mixes, meal replacement drinks, soups, and puddings.

2.7  Early aseptic packers Although Graves is credited with being the pioneer in producing commercially viable sterilized milk in the United States, concurrently Nestle with its Bear Brand was an early aseptic canner of milk in Switzerland. Other early entries in the United States were Tom Conley at Amboy Sterile Packaging in Amboy, Illinois; Dr. Robert Stewart’s plant in Corning, Iowa; the Land Ο’Lakes plant in Clear Lake, Wisconsin; Sol Zausner in New Holland, Pennsylvania; the Maryland–Virginia Milk Producers Association’s manufacturing plant in Laurel, Maryland; the Avoset Company in Gustine, California; the Borden company at its Galloway West plant in Fond Du Lac, Wisconsin; and Foremost Dairies in Newman, California. Many of these companies produced a single product. A good example is Andersen Pea Soup. Andersen’s Restaurant in Buelton, California, was famous for its split pea soup. Tom Andersen wanted to expand his sales and market his soup through grocery stores. He tried retort canning and was disappointed with the results, so he turned to aseptic canning in 1952 (Figure 2.4). This provided the flavor profile he wanted. After a succession of copackers came and went, Real Fresh bought the name and rights to can and market Andersen Soups, which now covers a span of over 40  years. Others of note were Avoset with its aseptically canned creams, and Foremost Dairies, which produced Fresh Tasting Evap, an aseptically canned evaporated milk, in Newman, California. Foremost also purchased and operated the original Med-O-Milk plant in East Stanwood, Washington, and the Ridgeland, Wisconsin, plant originally owned and operated by International Milk Processors in Chicago, Illinois. Real Fresh, Foremost, General Mills, Hunt Wesson, and the Del Monte were pioneers in aseptically packaged puddings. Borden was also an early entry with its aseptically canned eggnog from its plant in Fond Du Lac, Wisconsin. In 1982, Dairymen, Inc., a Georgia-based cooperative, began the production and marketing of sterilized milk in Tetra Brik containers. This continues to

Chapter 2:  United States history and evolution

15

Figure 2.4  Roy R. Graves.

the present under the Farm Fresh brand name. Early producers of cheese sauce and puddings for the institutional market in #10 cans were the AMPI plant in Dawson, Minnesota; Michigan Fruit in Benton Harbor, Michigan; John Gehl in Germantown, Wisconsin; the Land O’Lakes plant in Clear Lake, Wisconsin; Dean’s plant in Dixon, Illinois; Carnation with its Flash 18 process; and Real Fresh, Inc., in Visalia, California. Many of these plants have shifted from cans to aseptically filled pouches and bags for economic reasons. Real Fresh, Inc., was the only firm completely committed to aseptic food packaging. This required the flexibility of several different processing and packaging lines to pack the diverse number of products it marketed and contract packed for other store labels. There are now over 30 plants in the United States producing one or more low-acid, shelf-stable, aseptically packaged products. They range from milks (including soymilk), flavored milks and drinks, to cheese sauces and dips, puddings, soups, sauces (Aunt Penny’s Hollandaise Sauce, Atwater Canning Company, Atwater, California), diet drinks, infant formulas, creams, and milkshake mixes.

2.8  Restrictions for growth There are many factors that have restricted growth of UHT processing and aseptic packaging. The following list is not necessarily in order of dominance. First, due to lack of controls and technical specifications,

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much has been left up to the expertise and skill of the individual operators. Second, regulatory control of low-acid food products marketed unrefrigerated in the United States is onerous. The major players are the Food Safety Branch of the FDA and the Milk Safety Branch in the FDA, which oversee states’ inspection of milk under the Pasteurized Milk Ordinance. The USDA also plays two roles in that it is responsible for the inspection of dairy products sold to the government and for the inspection of meat products under the Meat Inspection Branch (FSIS) for all of the U.S. market. So, we not only have federal and state involvement, but also county and municipal health departments having to be dealt with and educated. Third, the cost of aseptic packaging is generally higher. Milk, for example, has a higher energy cost due to the higher processing temperatures, and the packaging costs are more because of the more robust barrier properties needed to maintain asepsis and oxygen barrier. The speeds of aseptic fillers are generally slower than pasteurized milk fillers, which also add to higher costs. The offsetting costs will be unrefrigerated storage and distribution along with reduced outdated returns, which plague pasteurized and ultra-pasteurized milk distributors. Thus a product-by-product evaluation must be carried out to determine if the advantages of superior value outweigh the additional cost of production and packaging.

2.9  Trends for the future The trends for the future continue to look bright. Improved processing equipment and controls will upgrade flavor profiles, which will provide greater consumer acceptance. These new methods will include the processing of particulates, such as meat and rice, beans, and other vegetables. Barrier properties of container materials will continue to improve, reducing cost and extending shelf life. Line speeds of processing and packaging, along with more automated controls, will be another important factor in cost reduction. UHT processing is energy intensive and can impart objectionable cooked flavors. The amount of cooked flavor is often dependent on the type of process used and the product itself. Direct steam injection or infusion is considered to give an improved flavor profile in some products, such as milk. Indirect systems, however, have improved immeasurably with the advent of hot water sets or the use of hot water under 33 psig in lieu of steam to reduce heat shock to the product. The cooked flavor and odor tends to dissipate with age. Look for more emphasis in the future on “cold sterilization” methods. Radiation, electron beams, pulsed light energy, and radio frequency (RF) are some methods that will receive considerable attention, and, hopefully, improved consumer acceptance. Other systems may include microfiltration and even a genetically modified bacteria that secretes a bacteriostatic

Chapter 2:  United States history and evolution

17

substance such as bacteriocins. This is already in use in cheese making here and abroad. In order to be competitive with high-speed retort canning speeds, aseptic canners and form–fill–seal units must operate at higher speeds in the future. To accomplish this, engineers need to come up with alternatives to heat and hydrogen peroxide as the method of sterilizing containers prior to filling. The exposure time required for heat and chemicals to achieve sterilization adds additional constraints, increasing line speeds. The “Flash 18” process used by Carnation is a unique hybrid alternative in that the product is filled in the can at 255°F in a room less than 18  psi pressure. This prevents flashing, and the product and container are sterilized simultaneously. Cans as a preferred container will continue to get a boost because of their strength and barrier properties. Lighter weight plate will reduce cost, and strength can be retained by injecting nitrogen or carbon dioxide in the headspace prior to sealing. Fillers have been developed for pouches that can fill particulates up to ¾ inch, in pouch sizes ranging from 8 fluid ounces to 4 liters. This technology will undoubtedly be made available to other types of fillers.

References Ball, C.O., and Olson, F.C.W. 1957. Sterilization in Food Technology: Theory, Practice, and Calculations, 2nd ed. New York: McGraw-Hill. David, J.R.D., Graves, R.H., and Carlson, V.R. 1996. Aseptic Processing and Packaging of Food: A Food Industry Perspective, Chapter 2. Boca Raton, FL: CRC Press. Goldblith, S.A., Joslyn, M.A., and Nickerson, J.T.R. 1961. Introduction to Thermal Processing of Foods, Volume 1. Westport, CT: AVI Publishing.

chapter 3

The U.S. markets for aseptic packaging Thomas Szemplenski

3.1  Development Even though aseptic processing and packaging was invented decades before, there was no significant activity in the commercialization of aseptic processing and packaging until the late 1960s and early 1970s when the Dole Canning System was used by food processors with foresight. These processors started to aseptically process and package shelf-stable milk, puddings, and soup. At about the same time, Tetra Pak, a Swedish company, introduced its laminated paper-aluminum foil-plastic container to the United States. The system was, at that time, a continuous form– fill–seal system for fluid pasteurized milk and beverages. The container was a tetrahedron. This package was extremely efficient in material use but complicated to pack or stack, and a real challenge to open. The U.S. licensee of this system was the Milliken Company in South Carolina, and in conjunction with Real Fresh of California, the Tetra system was modified to include a chlorine sterilizing bath of the packaging web. This allowed sterilized milk to be filled and sealed aseptically in a hermetically sealed container. These packages were followed by fruit products being aseptically filled using the aseptic bag-in-box system developed by William Scholle in the early 1970s. In 1981, Tetra Pak returned to the United States with a new and improved container. The basic system remained the same with a web of laminated material being formed, filled, and sealed in a continuous motion. What was different was that after the container was sealed and cut from the web, it was formed and folded into a rectangle or brick. This presented the consumer with a container that looked familiar and suitable, and could be displayed on store shelves. The real growth in aseptic processing and packaging was experienced starting in the early 1980s. Following Tetra Pak’s introduction of the Briktype package and the Scholle aseptic bag-in-box filler, other packaging 19

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alternatives started to be introduced, as well as other manufacturers of paperboard packaging and bag-in-box aseptic filling equipment. There are now quite a number of aseptic containing alternatives, including plastic cups, coffee creamers, steel drums, form–fill–seal pouches, plastic bottles of various polymers, and even aseptic bulk storage tanks (some of these tanks holding nearly 2 million gallons of aseptically processed acid products). The market growth or driving force of each aseptic packaging alternative is different and will be reviewed in this chapter.

3.2  Aseptic metal can market The Dole canning system was very reliable. It was based on heat for presterilization and maintenance of sterilization of the filler and the metal cans and lids. Filling speeds varied from 30 cans per minute for #10 cans (see Figure 3.1) up to 450 cans per minute for 4-ounce cans. There was considerable interest and acceptance of aseptic packaging of food into metal cans as Dole eventually supplied more than 60 canning systems, many of which are still in operation. As the learning curve for aseptic packaging using the Dole Canner increased, so did the number of different products that were aseptically filled. Products such as cheese sauces, ketchup, cream-style corn, baby food, eggnog, ice cream mix, banana puree, tomato paste, dietetic drinks, and sandwich spreads all were aseptically filled into metal cans using the Dole canning system. The driving force for interest and the growth factor in aseptically packaging into metal cans was the improved organoleptic and nutritional

Figure 3.1  Asceptically canned pudding. (Photograph courtesy of Real Fresh.)

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properties of the food being canned. The products no longer had to be overcooked for long periods of time in retorts. Instead of the food products being subjected to a temperature of 250°F from 45 minutes to sometimes 2 hours resulting in overcooking, it now could be homogeneously heated in a matter of seconds from an ambient temperature to around 275°F, held for a short period of time and then cooled very fast to a filling temperature of between 70°F and 90°F. Aseptic processing and canning resulted in dramatic quality and taste improvement in the food being processed and food processors embraced the technology. The Dole canning system was the only aseptic packaging system that was ever developed for metal cans, other than the aseptic filling system into 55-gallon metal drums invented in the 1970s by Fran Rica for tomato products. Unfortunately for the Dole system, alternative, less expensive aseptic packaging was developed that became the choice of food processors. Aseptic plastic cups, bag-in-box, and pouches are far less expensive than the metal can, so very few other Dole canning systems have been installed in the last 20 years.

3.3  Aseptic bag-in-box In the early 1970s, William Scholle of the Scholle Corporation, a leading manufacturer of flexible packaging of various polymers, visualized the potential for flexible packaging to replace the expensive, rigid packaging that was being used to transport food products such as tomatoes and other fruit products. Instead of using existing retorting technologies to commercially sterilize the product to be packaged in flexible packaging, he leaned toward applying a relatively new technology that was rapidly developing at the time, aseptic processing and packaging. Scholle engineered and manufactured a prototype of an aseptic filler to fill preformed, flexible bags. He tested and improved upon the initial design at Purdue University’s food processing facility in West Lafayette, Indiana. The first Scholle aseptic filler was developed to fill bags from 1 to 5 gallons. Improvements to the original Scholle were made to the point they now can aseptically fill bags up to 330 gallons. Scholle’s prototype aseptic filler was presterilized with steam, superheated water, and chlorine. The flexible bags were and still are sealed and presterilized by gamma radiation. Aseptic bag-in-box packaging was an immediate success (Figure 3.2). Prior to the development of aseptic bag-in-box packaging, most acid food products such as tomato paste and fruits for pies, yogurt, and so forth were either hot filled into #10 cans, aseptically filled into metal drums, or frozen in 30-pound plastic pails. Number 10 cans were and still are quite expensive, troublesome to open and dispose of, and yielded loss of product due to residuals, not to mention liabilities due to workers getting cut handling these containers. Fifty-five-gallon metal drums were very

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Handbook of aseptic processing and packaging

Figure 3.2  The Scholle aseptic bag-in-box filler.

expensive and additionally sacrificed yield at the use point. Thirty-pound plastic pails were the most common way to transport fruit that was frozen at the growing area and shipped all over the United States for remanufacturing into pies, fruit for yogurt, and so forth. Not only were the pails expensive, but the cost of freezing was additionally pricey. Economics is the main driving force for the aseptic bag-in-box market. As an example, a brief comparative analysis of aseptic bag-in-box compared to product packaged into number #10 cans will be presented. Many food products destined for food service are packaged into #10 cans and delivered 6 cans per case. Food service is one of the largest markets for bag-in-box. Case of #10 cans • A #10 size can will normally contain approximately 96 ounces, therefore a case of #10 cans will usually be about 4.5 gallons. • Although the price of a #10 can will vary depending upon the cost of the raw material at the time and the size of the customer based on the number of cans purchased, the average price for a #10 can at the time of this writing is $0.75 each. • 6 × $0.75 = $4.50 per case (usually about 4.5 gallons) 5-gallon aseptic bag-in-box • A 5-gallon, presterilized bag will vary in price depending upon packaging materials, barriers, metallization, and so forth, but usually will cost between $0.80 and $1.20. If an average price of

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$1.00 is used in the calculation, the savings would be $4.50 – $1.00 = $3.50 per case savings. • Adding the price for the corrugated container would increase the price of the flexible bag packaging by as much as $0.20 more. If this is entered into the comparison the savings would be $3.20 for the aseptic bag-in-box compared to a case of #10 cans, but it should be noted that the bag holds approximately a half a gallon more product. An extended economic comparison was generated for an actual food processor. This food processing facility utilizes 9 million #10 cans per year. During the fresh-fruit season it packages all the product into #10 cans. During the off-season it opens the #10 cans and reprocesses the product into alternative packaging. To elaborate on the initial comparison: • 9,000,000 #10 cans divided by 6 cans per case = 1,500,000 cases × 4.5 gallons per case = 6,750,000 gallons of product being processed • Cost of cans: 9,000,000 × $0.75 = $6,750,000; yearly cost of #10 cans • Cost of bag-in-box: 6,750,000 gallons divided by 5-gallon bags = 1,350,000 bags @ $1.00 per bag = $1,350,000 yearly cost of bags • Yearly savings to package product into bag-in-box: $6,750.000 – $1,350,000 = $5,400,000 Additionally, the processor advised the cost of reopening and disposing of the #10 cans was approximately $1,500,000 annually. Further economic savings to be realized by aseptic bag-in-box compared to rigid metal cans are: • Reduced space required for bags compared to empty and full metal cans • Reduced shipping cost • Reduced liability • Reduced disposal cost Based on advantages similar to those described in our comparison, economics is the main driving force for the aseptic bag-in-box market. Other manufacturers of food packaging equipment realized this and quite a few competitors to Scholle have introduced their versions of aseptic fillers for bag-in-box. There are now at least 10 different aseptic bag-inbox fillers installed in the United States alone with more than 200 aseptic bag-in-box fillers operating. There are also approximately six major suppliers of presterilized aseptic bags of various polymers and oxygen barrier materials. Improvements have been made in aseptic bag-in-box fillers to the extent that several have received U.S. Food and Drug Administration (FDA) validation for aseptically filling low-acid foods, and bag sizes have increased to the point some of the fillers can fill bags up to 300 gallons.

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Handbook of aseptic processing and packaging

The market for aseptic bag-in-box is actually two distinct markets: the market for product packaged in smaller bags from 1 to 5 gallons and the market for larger bags packaged in bags from 55 to 300 gallons. The market for smaller bags is generally for product destined for the food service industry. Initially the market for the smaller bags was for acidified products, such as stabilized fruit for pies and yogurt, but this market has given way to saturation and the larger bags. The market segment for smaller bags that is experiencing growth now is for low-acid food products such as prepared sauces for restaurants, soups, chili, milk, and condiments, like ketchup, salsa, mustard, and single-strength juices. There is hardly a convenience in the United States that does not have a dispenser from Gehl’s installed to dispense warm cheddar cheese sauce and chili over nacho chips. These products are aseptically processed and packaged. It is estimated that there are more than 100 aseptic bag-in-box fillers installed filling smaller bags in the United States. This market is not mature. Most assuredly more products will be aseptically packaged into flexible bag-in-box packaging. There are approximately 140 aseptic fillers installed to fill larger (55 to 300 gallons) bags. This market is additionally divided into two predominate markets: one for tomato paste and the other for citrus products. The total market for bulk bags in the United States is estimated at 4,500,000 units in 2008. Based on the average price for a bulk bag in 2008, this would amount to an approximate $50 million market for bags. With approximately 90 aseptic bag-in-box fillers for bulk packaging operating, the larger of the two markets for bulk bags is for tomato products. California grows and supplies most of the tomatoes in the United States and aseptically packages paste and diced tomatoes for shipment to other parts of the country. The product is harvested, condensed, and aseptically processed and packaged in California. It is then shipped to various points around the United States to be reprocessed into ketchup, sauces, soups, and so on. JBT FoodTech is the leading manufacturer of aseptic fillers for bulk bags, although JBT FoodTech does not manufacture the packaging. The demand for aseptic bag-in-box packaging for tomato product continues to grow but at a slower pace than when the aseptic bag-in-box fillers were rapidly replacing nearly all the aseptic drum fillers. Nearly all tomatoes in California that are harvested and packaged to be reprocessed are aseptically filled into the bag-in-box. The other major market for bulk aseptic bags is in the citrus industry. The citrus industry does not have as many aseptic bag fillers installed as the tomato industry, however, the citrus industry is afforded two crops creating an approximate season of 250 days compared to the 100-day tomato season. In the 1990s, the citrus industry embraced aseptic filling of juice into bulk bags. Almost all the operating aseptic fillers are for the larger 300 gallon bags, and although Scholle and JBT FoodTech have a few aseptic fillers installed for citrus

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products, the DuPont/Liqui-Box StarAsept filler is the predominate filler being used in the citrus industry. The market for citrus products beings aseptically stored in the bag-inbox has been in steady decline for the past decade. Aseptic bags are rapidly being replaced with aseptic bulk storage tanks capable of aseptically containing millions of gallons of citrus juices. Even at that, industry sources have reported that in 2008, approximately 1.5-million bulk aseptic bags were utilized in the citrus industry (P. Brocher, personal communication, 2008).

3.4  Aseptic paperboard market In the early 1980s, Tetra Pak returned to the United States with a new and improved package. The basic system remained the same with a web of laminated material being form, filled, and sealed in a continuous motion. What was different was that after the package was sealed and cut from the web, it was formed and folded into a rectangle or brick. This presented the consumer with a container that looked familiar and suitable to be displayed on the store shelves. The real functional feature was the straw for the smaller containers that was designed to puncture an opening at the specially scored spot. This made the container popular with many consumers who like the portability and ease of consuming whatever the package contained. Aseptic milk and flavored milks experienced their first real introduction to the mass market in Tetra Pak’s Brik-Pak packaging. At that time the demand for Tetra Pak aseptic filling equipment for acid products such as fruit juices and flavored liquid beverages far exceeded the demand for fillers for milk. It was not until the processing of milk was significantly improved upon with the introduction of steam injection when the real growth occurred in the dairy segment. The acceptance of juices in Tetra Pak Brik packaging was phenomenal. The consuming public embraced the new package and products with a passion as evidenced by the grocery store shelves that were lined with the many different products packaged and offered by the many beverage processors who installed Tetra Pak fillers or had the product copacked at various locations (Figure 3.3). The market for new Tetra Pak fillers for acid products is somewhat static at the time of this writing due to the many fillers that are already installed and operating. However, as the learning curve in aseptic processing and packaging improved, so has the scope of new products that are being aseptically packaged into paperboard-laminated containers. It appears that new products are being aseptically packaged every day. Products such as soups, broths, nutritional drinks, and many sauces like the ones pictured in Figure  3.4 are all being aseptically packaged into paperboard-type containers.

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Handbook of aseptic processing and packaging

Figure 3.3  Aseptic product in Tetra packaging. (Photograph courtesy of Tetra Pak.)

Figure 3.4  Low-acid aseptic product in Tetra packaging. (Photographs from sales literature.)

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It appears that the real growth in the paperboard laminate packages is in specialty food and beverages other than juices and fruit flavored beverages. Tetra Pak now has approximately 200 aseptic fillers installed and operating in the United States. Almost half of these fillers are now for lowacid beverages and other foods. This trend will continue. The other supplier of aseptic filling equipment for products into paperboard-laminated packages is SIG Combibloc. Unlike the Tetra Pak form–fill–seal principle of producing sterile packages, the Combibloc filler uses preformed packages that are supplied to the filler, folded flat. The filler then automatically opens, forms, sterilizes, fills, and seals the packages. The packages with the Combibloc filler are sterilized with hydrogen peroxide and hot air. Both the Tetra Pak and Combibloc fillers are FDA validated for aseptically filling low-acid foods, but the Combibloc filler was the first filler used in a commercial aseptic processing system containing a low-acid food with particulates. The installation is located at a Campbell Soup facility in Canada aseptically filling soups with small particulates like the one pictured in Figure 3.5. Tetra Pak is by far the leading supplier in the world for the supply of aseptic fillers and packaging material. Aseptic packaging at Tetra Pak is dynamic. They now have many different types of fillers designed to aseptically fill into many different packaging configurations, the most recently being a form–fill–seal gable top design. One thing can be counted on with Tetra Pak and that is innovation.

Figure 3.5  Low-acid aseptic product containing particulates.

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Handbook of aseptic processing and packaging

3.5  Aseptic plastic cup market The market for food products aseptically filled into plastic cups enjoyed tremendous growth starting in the early 1980s. Robert Bosch Company installed the first aseptic filler in the United States for filling food products into plastic cups. This installation was followed by a number of other manufacturers such as Hassia, Metal Box, ERCA, Benco, Gasti, and Hamba. The Gasti and Hamba fillers never received FDA validation for aseptically filling low-acid foods but were used as extended shelf-life (ESL) fillers for refrigerated products. The introduction of these aseptic fillers for filling into plastic cups all but took away the market for the Dole canning system due to high speeds and economics of packaging materials. In all, 26 aseptic fillers and 12 more extended shelf-life fillers were installed starting in the 1980s. Due to excellent engineering, high production speeds, lack of chemical sterilants, and aggressive marketing, Hassia, now OYSTAR Hassia, has become the dominant supplier of aseptic cup fillers in the United States (Figure 3.6). The latest OYSTAR Hassia aseptic cup filler can fill almost 1700 cups per minute (C. Ravalli, personal communication, 2010).

Figure 3.6  Some products aseptically filled using an OYSTAR Hassia filler.

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The first products to be aseptically filled into plastic cups were puddings. The interest in aseptic filling into plastic cups was driven not only by the economics of higher production and less expensive packaging, but also by the much improved organoleptic quality of the aseptically processed pudding. Over the years the scope of products expanded to include cheese and other sauces, condiments, soup, baby food, and flavored gels. Of late, however, the market for aseptic fillers for cups has softened considerably and not many new aseptic cup fillers have been installed. Manufacturing sources have advised that this is most likely due to the capital-intensive cost of aseptic processing and packaging and saturation.

3.6  Aseptic pouch market The aseptic pouch market is believed to be in its infancy. This is an underdeveloped market that is expected to explode with activity mainly due to the economic savings in packaging, but also due to −− Improved nutritional and organoleptic quality of the food product compared to retorting or hot filling −− Convenience compared to #10 cans −− Less disposal cost −− Less space required −− Less manpower requirement at the end use point The economic savings are exceptional and are the main driving force. The predominate market for product to be supplied in pouches is the institutional or food service market for replacing product in #10 cans. Cans are not only costly but take up considerable space, can be difficult to open and dispose of, and incur liability cases from users cutting themselves handling them. Aseptic filling equipment and packaging material suppliers in addition to food processors have advised that #10 cans generally cost about $0.75 per can. They additionally have advised that a comparable pouch costs approximately $0.27. That is an overwhelming difference in cost. For each million cans a food processor uses it would save approximately $480,000 in packaging cost alone. Another major savings is in floor space. The photograph in Figure 3.7 taken (with permission) at a trade show demonstrates the space required for 832 #10 metal cans compared to the space requirement for 832 pouches in the roll on the bottom left or in one corrugated box on the bottom right of the photograph (B. Pritchard, personal communication, 2010). Robert Bosch was the first company to develop an aseptic filler for flexible pouches. Bosch supplied a number of aseptic pouch fillers to replace fillers that were using the Dole canning system filling puddings and cheese sauces in #10 cans. The market for cheese sauce exploded with

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Handbook of aseptic processing and packaging

Figure 3.7  Space requirements for pouches compared to cans—each showing 832 packages.

activity, and today there is hardly a convenience store that does not have a dispenser for aseptic cheese sauces for chips. Inpaco, DuPont/Liqui-Box, Fres-co, OYSTAR Hassia, and Cryovac all have developed aseptic fillers for pouches that operate at varying filling capacities, size of pouches, handling of different particulate size and technology, such as fitment attachment offered by Fres-co. As the technology to aseptically process and receive FDA validation for food products containing particulate matter develops, so will the market for aseptic pouch fillers and packaging material. The food service industry will embrace these food products as a wonderful alternative to not only metal cans but also consistent and organoleptically more palatable foods compared to over- or undercooking foods due to human judgment by restaurant cooking staffs.

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3.7  Aseptic plastic bottle market Besides Tetra Pak’s paperboard laminate fillers, the market with the most activity in recent years has been the introduction and installation of aseptic fillers for plastic bottles of polypropylene (PP), high-density polyethylene (HDPE), and polyethylene terepthalate (PET). The beverage industry has embraced the plastic bottle. The first aseptic plastic bottle filler installed in the United States and validated for the filling of low-acid foods was manufactured and installed by Bosch for nutritional beverages. Since then many aseptic bottle fillers have been installed to fill high-acid beverages, whereas others are using their aseptic fillers to fill extended shelf-life, refrigerated dairy products. Many fillers being used in an ESL mode are not FDA validated and therefore cannot be used to fill shelfstable low-acid beverages. In all there are nine manufacturers of aseptic filling equipment with installations in the United States; six manufacturers have received FDA validation. In all, there are approximately 75 installations, aseptically filling high- and low-acid beverages including extended shelf-life products. These suppliers include: Bottle Filler Manufacturer Robert Bosch OYSTAR Hamba KHS Krones Procomac Serac Shibuya Sidel–Rotary Sidel–Linear (Tetra Pak) Stork

FDA Validation Yes No Yes No Yes No Yes No Yes Yes

Consumer acceptance of the plastic bottle is outstanding and is chipping away at the market for beverages that were previously supplied in paperboard or Brik-type packages. The primary reasons for this acceptance are, but not limited to: • • • • •

With plastic bottles, the consumer can see the product The bottles fit easier into the cup holders in automobiles Bottles are easier to open and easier to reclose Bottles can come in many sizes and shapes They are easier to recycle

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Handbook of aseptic processing and packaging

The market for beverages is interesting and very dynamic. It is also quite segmented between high- and low-acid beverages. Initially, beverage processors could justify the capital-intensive aseptic processing and filling system based on the reduced cost of resin compared to a heat-set bottle for hot filling. Initially, this cost difference could be as much as 20% more than a lighter weight bottle used on the aseptic fillers. Over the years the blow molders have improved upon the technology and have reduced the cost of the heat-set bottles to the point that it is now economically more attractive to hot fill high-acid beverages. In a detailed economic comparative analysis of hot fill versus aseptic including, but not limited to, capital cost for processing and filling equipment, bottle cost, utility costs, and operating costs it was calculated that the overall difference between the cost to hot fill versus aseptically filling was less than 1 cent. It is no wonder beverage processors are now returning to hot filling high-acid beverages. The market for low-acid beverages is quite different. It is almost impossible to hot fill low-acid beverages for shelf stability, therefore aseptic processing of mostly dairy products and some other high-acid beverages is divided between aseptic shelf-stable beverages and extended shelf-life beverages. Although there are a number of aseptic fillers producing shelfstable dairy products, this is not a growing market. U.S. and Canadian consumers are accustomed to drinking their dairy products refrigerated and prefer them that way. The market growth for low-acid beverages in plastic bottles is in extended shelf-life products. Extended shelf-life products in most cases are processed the same way as aseptic products with the general exception of two differences: first, with extended shelflife products, the end product must be distributed refrigerated, therefore the filling temperature is approximately 40°F or less; second, the products are normally not filled using an FDA-validated filler. This does not mean the filler is not clean and sterile. It only means the filler more than likely did not go through the validation process. In both cases, the processing system and filler are both presterilized prior to production. With extended shelf-life dairy products processors can generally expect a 90- to 110-day refrigerated shelf life.

chapter 4

Aseptic processing equipment and systems Thomas Szemplenski

4.1  Introduction Aseptic processing of food and beverages is a continuous commercial sterilization of these products preceded by the sterilization of the processing system. Many different types of equipment can be employed in the development of an aseptic processing system, however, each must be capable of being sterilized and maintained in a sterile state during processing. Compared to all other methods of sterilizing food in pursuit of a shelf-stable product, aseptic processing subjects the product to substantially reduced heating and cooling time resulting in an end product that is most often more nutritious and organoleptically more palatable. Many people believe that aseptic processing and packaging was invented in the early 1980s when Tetra Pak introduced the first bricktype paperboard packaging into the United States. In reality, the first patent (no. 2,029,303) for aseptic packaging was granted to C. Olin Ball on February 4, 1936, for aseptic filling into metal cans. There was no significant activity in the commercialization of aseptic processing and packaging since the patent was issued until the late 1960s and early 1970s, when the Dole aseptic canner was invented and a number of processors started aseptically packaging shelf-stable puddings. This was followed by Tetra Pak form–fill–seal paperboard and aseptic bag-in-box systems. Even after all these years, aseptic processing and packaging remains a dynamic means of preserving food and beverage products. Many changes have been and continue to be made to aseptic processing and packaging systems. The more paramount changes or improvements in processing will be identified in this chapter.

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Handbook of aseptic processing and packaging

All aseptic processing systems use continuous processing techniques. In this regard, the primary components in aseptic processing systems will be reviewed and include: • Blending tank/formulation of product • Metering pump for accurately controlling the flow of product through the system • Continuous heat exchangers for rapidly elevating the product to the required sterilization temperature • A continuous holding tube to hold the product at the sterilization temperature long enough to effect commercial sterilization • Continuous heat exchangers for rapidly cooling the product to the filling temperature • Steam-sealed, air-operated valves to direct the product to the desired locations • Accurate controls for the system to ensure presterilization of the system and sterilization of the product • Optional aseptic surge tank The equipment used in any aseptic processing system must fulfill the same sanitary and regulatory requirement as those used in conventional food processing in addition to those necessary for sterilization and maintenance of a sterile state during processing. Formal regulations for the design of aseptic processing equipment do not exist, however, principles that must be followed in the design of aseptic processing equipment have been determined over the course of the evolution of aseptic technology. These principles have been developed through experimental work in food and dairy processing operations and testing laboratories.

4.2  Aseptic processing equipment 4.2.1  Basic requirements of aseptic processing equipment

1. Like all other food processing equipment, it must be of sanitary design and capable of being thoroughly cleaned. 2. The equipment must be capable of being sterilized. The presterilization is usually accomplished with steam, chemicals, or hightemperature water at elevated pressures. 3. The equipment should be free of any cracks, crevices, or dead spots so the sterilizing media can adequately contact all the equipment surfaces. 4. The equipment must be capable of being maintained in a sterile state. This includes maintaining a closed system at greater pressure than the surrounding area or heat-exchange media.

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5. The equipment must be capable of being maintained in a constant operating mode. 6. The equipment must conform to design, state, and federal regulatory codes if they exist.

4.2.2  Blending vessel, balance surge, formulation of product Delivering a uniform product to the timing pump is important. Any inconsistency in the product could potentially affect the overall sterility of the product. If one portion of the batch has a different consistency and percentage of ingredients than another, not only will the final product vary but the different characteristics of the batch could jeopardize the sterility. The blending vessel and the balance tank for the supply of product to the aseptic processing system may or may not be the same, but should be of sanitary design. This vessel does not need to conform to aseptic requirements, such as steam sealing the moving parts, as they are upstream of the sterile part of the system. Many liquid products, such as milk and juices, must be standardized to the desired solids and viscosity. Usually, formulating or standardizing of fluid products is done with vertical tanks that have vertical agitation. Occasionally, if the product is easily kept at a constant concentration, the agitation may be horizontal, such as milk storage tanks with horizontal propeller-type agitators. With citrus products, the final product to be delivered to the consumer is a combination of juices produced at varying times of the year. This will require a very good mixing system to ensure that the final composition of the product contains the proper amounts of all components. Mixing should be complete and thorough to ensure the product has equal composition throughout. If pulp is to be added, the pulp should be metered into the process stream consistently, so the proper amount exists throughout. The incorporation of pulp can be a very difficult task. Pulp that is dry will tend to float and must be compensated for by agitation without adding a significant amount of air. Formulated products, such as fruit for yogurt that contain sweeteners (dry, liquid sugar, or corn syrup), fruit or fruit pieces, thickeners (such as starches, pectin, and gums), and other ingredients (such as flavors, colors, and antioxidants) are usually blended in horizontal mixers. A good horizontal blender will keep all materials in suspension so the final product will be consistent. Difficult to incorporate ingredients such as pectins are usually mixed with water in a high-shear mixer and then added to the final formulation of the fruit-based product in the blender prior to entering the aseptic processing system. In other cases, starch or viscosity enhancers are added to water. The mixture is heated and then cooled resulting in a slurry with enhanced

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viscosity. Fruit pieces, which can tend to float or settle, are then added to this viscous mixture to effect an even composition of the fruits throughout.

4.2.3  Timing pump The timing or metering pump is one of the most critical areas of an aseptic process system. Pumping of the product through the system is extremely critical and must be done at a measurable, constant rate. Thermal destruction of pathogenic microorganisms is a time–temperature relationship. In a continuous processing system, the food product must be held for a specific amount of time at a designated temperature to ensure destruction of unwanted bacteria. The time and temperature cannot deviate below these set parameters otherwise complete destruction of the microorganisms will not result and food spoilage will occur. To ensure an accurate time at a set temperature, the flow through the aseptic system should be as consistent as possible. Many aseptic processing systems utilize rotary positive displacement or progressive cavity pumps as the metering pump (Figure 4.1). Some aseptic systems that are processing low-viscosity products utilize centrifugal pumps as the metering pump and control flow by means of a backpressure valve. All rotary positive displacement and centrifugal pumps are designed to slip. The degree of slip is directly related to: • • • •

Clearances, age, and wear of the moving parts of the pump Viscosity of the product or water being pumped Processing pressure drop in the system Processing temperature of the product being pumped

Therefore, the use of rotary positive displacement or centrifugal pumps as metering pumps in aseptic processing systems can introduce

Figure 4.1  Typical rotary positive displacement pump.

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Figure 4.2  High-pressure pump.

some degree of variability to the very critical flow of the product through the system, making temperature control of the product that much more difficult. Additionally, quite often heat exchangers will tend to foul and air-operated valves may be opening or closing causing a change in the flow pattern and resultant pressure of the system. Rotary positive displacement or progressive cavity pumps tend to vary output based upon this inconsistent pressure. Many times high-pressure piston or reciprocating piston pumps are used as the metering pump (Figure 4.2). Slippage in a high-pressure piston pump is almost nonexistent, therefore, the rate at which the product is being transferred through the system is constant. This assumes the piston pump is fed adequately and has the net positive suction head required to pump the full amount of which it is capable. If the total pressure against which it is pumping is not excessive, piston pumps will produce a constant flow.

4.2.3.1  Pumping of foods containing particulates Due to the continued interest in aseptically processing food products containing discrete particulates, many processors are utilizing a reciprocating piston pump as the metering pump in the system. A reciprocating piston pump like that which Marlen International manufactures is ideally suited for aseptically processing food products containing distinct food pieces and has zero slip. The Marlen reciprocating piston pump is specifically designed to deliver a consistent and accurate flow, and not slip under any variable conditions including temperature or viscosity changes in the product or any pressure deviations (Figure 4.3). The Marlen pump consists of two hydraulically driven reciprocating pistons. The pistons are housed in two cylindrical sleeves within a pumping

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Figure 4.3  Marlen reciprocating piston pump. (Photo courtesy of Marlen International.)

chamber. The pumping of the product alternates from one piston to the other with a constant flow rate. Depicted in Figure 4.4 (step 1) is the left piston and sleeve retract. This retracting action makes a void, creating a strong suction that draws the product into the pumping chamber areas ahead of the sleeve. The left sleeve then moves forward to trap the product and seals against the outlet. The left piston then begins its forward movement The Heart of the Marlen System Right side Left side Piston Sleeve

1.

Product Valve

2.

3.

Figure 4.4  The operating principle of the Marlen pump. (Courtesy of Marlen International.)

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to compress the product to the same pressure that is in the right piston (step 2). As the right piston nears the end of its pumping stroke, the product valve shifts to open flow from the left side and blocks the flow to the right side (step 3). The right side can now retract and reload the same as the left side did in step 1. During front-valve shifting there is no change in product flow as the front valve opens on one side and simultaneously closes on the other.

4.2.4  Heat exchangers In most cases, the primary reason for aseptic processing is to quickly destroy the unwanted microorganisms without adversely affecting product quality. Generally the product to be processed dictates the type of heat exchangers that will be used to sterilize and aseptically cool the product. Many times a combination of different types of heat exchangers are used in the same aseptic processing system to optimize product quality and production efficiency. For each product, one system will be ideal. Consideration should be given to the sterilization of the product that will produce the highest quality finished product.

4.2.4.1  Heating: Sterilization of the products There are multiple ways product can be continuously heated to effect sterilization of the product. The more paramount methods include: • • • • • •

Direct steam: steam injection or steam infusion Plate heat exchangers Tubular heat exchangers Scraped surface heat exchangers Ohmic heating Microwave heating

4.2.4.2  Steam injection or infusion heaters Steam injection or infusion has been of interest since aseptic processing was initially conceived. The theory was that if the product was heated very quickly, adverse quality to the product (burnt flavors and odors, color, and stability) would be minimal. With steam injection, steam is injected into a continuous flow of product to heat it to the desired sterilization temperature. When steam infusion is used, the product flows through a chamber filled with steam. In either case, the product is heated in the fastest possible way. With either steam injection or steam infusion, water is added to the product and this water generally must be removed. Steam injectors and infusers have a variety of ways of introducing steam into the product. The objective of most of these is to provide a design that will have the least number of mechanical problems, including

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vibration and pounding, which is caused by the steam condensing in the product. The steam that condenses into the product becomes part of the product, therefore, the quality of the steam added is very important. In the United States, culinary steam, per the definitions established by 3A as minimum, should be used. Steam used in a steam injector or infuser should be produced using distilled water with no added chemicals that could react with components of the product. A concept developed to produce a better quality product and reduce the mechanical vibrations associated with conventional steam injection systems was the steam infuser. In a steam infuser, the product is introduced into a chamber that contains steam at the temperature needed for sterilization. When the product enters the hot steam atmosphere, the product is heated to the temperature of the steam. Some of the products that utilize steam injection and infusion in aseptic processing systems include dairy, juice-based drinks, soy products, creams, ice cream mix, and tomato paste. With steam injection or infusion devices, often a flash cooler is used. The flash cooler has dual purposes. First, it reduces the sterilization temperature in a very short time, and, second, it removes water from the product. An added bonus is that undesirable volatile odors and flavors of the product are removed. Ideally, with milk or other dairy products, the temperature is accurately controlled so that the amount of water flashed from the product is the same as that added as steam, so there is no dilution or concentration. However, if the flash chamber is operated at pressures below atmospheric (vacuum), contaminants will try to enter it. Because of this, all potential areas of leakage, such as unions, connections for temperature/ pressure or vacuum probes, manholes, or covers must be flushed. Often steam is used in the flush area and is maintained as a barrier so any possible contaminants that may try to enter the sterile zone (because of the reduced pressure) are first drawn through the sterilizing media. With certain heat-sensitive products this can be a problem. Sometimes a sterile chamber is used afterward that may be at reduced pressures but still at pressures above atmospheric. In this manner, the pressure of the product flowing through the flash chamber can be maintained above atmospheric, so the product may be partially cooled safely. The use of a sterile flash chamber at this point still may be required because the temperature may not be high enough to sterilize contaminants should they enter. Another problem generally related to steam injection–flash cooling systems is they are quite expensive. Whether the system operates at 5 gallons per minute or 100 gallons per minute, the controls, interlocks, and other safety devices, for a practical commercial system, must be incorporated.

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Figure 4.5  A typical plate heat exchanger. (Courtesy of AGC.)

4.2.4.3  Plate heat exchangers The first aseptic processing systems utilized plate heat exchangers for either heating the products, cooling the products, or both (Figure 4.5). Beverages and fairly low viscosity food products such as sauces, milk, and juices still utilize plate heat exchangers in the aseptic processing systems. In essence, the use of plates was an extension of commercial pasteurizing operations accomplished at lower temperatures. Some of the inherent problems with plate heat exchangers in aseptic processing systems are their pressure limitation and their ability to be cleaned in place (CIP). Plate heat exchangers were originally developed for use in food applications where they could be disassembled, manually cleaned, inspected, and reassembled into the plate pack. With higher capacity systems, plates are now cleaned in place by washing with various solutions. One must use caution when utilizing plate heat exchangers at aseptic processing temperatures because the product can tend to burn onto the plates. CIP operations may not remove all of the burnt material adversely affecting flow rate and temperature control. Another problem with cleaning of plates is with juices containing pulp. When juice-containing pulp is processed, the pulp tends to gather in the low-velocity section of the plate

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and removing it using CIP is difficult. In either of these two mentioned instances, continuous fouling increased over a period of days, weeks, or months, the initial sterilization cycle may not be adequate to sterilize the plates. The plate heat exchangers can then contaminate the commercially sterile cold product. Differential pressure control with plate heat exchangers is essential. On one side of the plate is a sterile cool product. On the other side of the plate is potentially unsterile heat exchange media. If the plate heat exchanger does not have greater pressure on the sterile side of the plate heat exchanger than that on the unsterile side, then contaminants can literally be sucked into the already sterile product. Proper and precise control of differential pressure is required so that the pressure on the sterile side of the plate heat exchanger is always greater than the product on the unsterile side of the plates. In addition to other potential problems with plate heat exchangers, there can be mechanical problems. When plates are sterilized with heat they expand. However, the frame and tie bolts that hold the sections of the frame together (follower and fixed ends) do not expand. This puts enormous stresses on the gaskets and failure on the relatively thin plates can be at an accelerated rate. This is further accentuated due to the elastomers used for gaskets. The gaskets generally soften and weaken at the elevated sterilization temperatures and leakage can occur during sterilization. When this happens efforts are usually made to put more pressure on the gaskets by tightening the plate pack; however, this puts more stress on the gaskets to the point they sometimes sheared and failed. Since plates were initially used, other heat exchangers have been designed and perfected such that plate heat exchangers are being replaced by more reliable and efficient heat exchangers in aseptic processing systems. Not only do the new heat exchanger designs withstand sterilization operations, but they also operate in a reliable manner so sterility is not in question.

4.2.4.4  Tubular heat exchangers In pursuit of more efficient aseptic processing systems, equipment manufacturers and design engineers have continued to improve on the design of tubular heat exchangers. Whereas in the past, most heat exchangers in aseptic processing systems utilized either plate heat exchangers for very low viscosity beverages and scraped surface heat exchangers for all other products, most of the newer aseptic processing systems utilize tubular heat exchangers or a combination of tubular heat exchangers with steam injection or infusion. In some of the early systems when aseptic technology was first being developed and commercial lines were being installed, the processing flow rates were quite low. Some simple tubular heat exchangers were used in lieu of plate heat exchangers. A section of small-diameter tubing was

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formed into a helical coil, which was then placed in a casing with flanges on both ends. The coil entered the casing through a packing gland and discharged in the same manner. Inlets and outlets were provided for steam or water. On heaters, steam was introduced and as the product was pumped through the small-diameter coiled tubing it was heated indirectly by the steam. Condensate was trapped off the bottom and this sufficed. The coolers were made by introducing countercurrent cold water in the shell to cool the product. For low-capacity systems (3 to 4 gpm) and on products that were easy to heat and cool, such as milk and juices, this was perfectly adequate. Some of these heat exchangers are still being used today, but most of them are in research and development labs (Figure 4.6). As filling equipment improved and container sizes increased, the production rate of the systems increased, therefore this design was inadequate for the higher capacities. At the higher flow rates, the number of tubes became excessive and mechanical problems such as vibration and water hammer became a problem, therefore, design modifications had to be made. One design that came from this basic idea was to place a core inside the tube to displace volume. The stainless steel tube was wrapped tightly around the core, and the shell was then wrapped around the tube that would force the water or steam to flow in a helical manner countercurrent (when a liquid coolant was used) to the product in the tubes. This design was somewhat improved but resulted in certain other problems, such as excessive vibration of the tube, particularly with heaters using steam, which caused many tubes to fail. Although effective in reduced maintenance and able to handle much higher pressures compared to plate heat exchangers, the first tubular heat exchangers were more expensive, tended to develop product building up on the walls of the heat exchangers due to burn-on, and were still limited to low-viscosity products. Within the last 15 or 20 years, the design improvements to tubular heat exchangers have been phenomenal. Various methods of tube configurations and twisted or corrugation have improved flow patterns through tubular heat exchangers to the extent of substantially reduced fouling and increased processing time between cleaning and resterilization. Several designs of new tubular heat exchangers are depicted in Figures 4.7, 4.8, and 4.9. The new designs have also allowed the tubular heat exchangers to process food products containing discrete particulate matter with minimal or no damage to the particulates. Food products such as puddings, cheese sauces, diced tomatoes, soups, and others that were previously aseptically processed on very expensive and maintenance-demanding scraped surface heat exchangers are now being replaced with new, less expensive tubular-type heat exchangers. With no moving parts, tubular

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Figure 4.6  A coiled heat exchanger. (Diagram courtesy of Advanced Process Solutions.)

heat exchangers are also much less expensive to operate and maintain. The new tubular heat exchangers use pressurized hot water for heating and tower or refrigerated water for cooling and regeneration. The water acts as a cushion and tube failure has all but been eliminated. In essence, the liquid acts as an absorber of the energy. Tubular heat exchange systems can be very compact and even SKIDDED facilitating installation. A couple of tubular heat exchange systems are depicted in Figures 4.8 and 4.9.

4.2.4.5  Regeneration Regeneration is generally used when plate or tubular heat exchangers are used in the aseptic process. Regeneration normally consists of the cold incoming product cooling the hot sterilized product, and in turn, the hot sterilized product heating the cold incoming product. Other types of regeneration include the use of heating or cooling media. The process

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Figure 4.7  Various types of tubular exchangers. (Diagram courtesy of Advanced Process Solutions.)

of regeneration basically results in free or reduced-cost heating and cooling. When product-to-product regeneration is used, extreme care must be taken to keep the two continuous flows apart, because the raw incoming products contain microorganisms that can contaminate the product that has been sterilized. If direct regeneration is used where a hot product is separated by a relatively thin piece of metal, as in plate heat exchangers or gasket, from the cold product that contains large bacteria counts, even a small leak can cause contamination.

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Figure 4.8  Commercial aseptic processing systems using tubular heat exchangers. (Courtesy of Advanced Process Solutions.)

Figure 4.9  Commercial aseptic processing systems using tubular heat exchangers. (Courtesy of Advanced Process Solutions.)

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When the heating or cooling media is used for regeneration, the regeneration is usually indirectly accomplished. The hot sterilized product is used to heat water, which in turn heats the raw incoming product, and the water is cooled. Depending upon how the system is designed, the hot water next to the cold raw product can be sterile if it is heated to a high enough temperature. In some cases, sterile water can be generated by filtration. Filters, if properly specified, and the system properly designed, will remove all, or at least most, of the organisms so the cooling water will contain no organisms. Regeneration should be engineered so the pressure on the sterile side of the heat exchanger is always higher than the product on the raw side. If there is ever a leak in the heat exchanger, the leak would be from the sterile product to the raw product or media. If per chance the flow is the other way, the sterile product could get recontaminated. If the heat exchanger has no gaskets and is made of heavy wall tubing, this should not be a problem. Contamination can be a major problem in regenerative systems and they should be arranged so this does not happen. Regeneration is most logically used if only one product is being processed or many products that are very similar are being processed and all other conditions are the same. If product characteristics vary, then the temperature profiles will most probably vary.

4.2.4.6  Scraped surface heat exchangers Most of the initial aseptic processing systems for the ever-popular shelfstable puddings and cheese sauces utilized scraped surface heat exchangers (SSHE) for heating and cooling the food products. A photograph of an aseptic processing system utilizing scraped surface heat exchangers is depicted in Figure  4.10. This particular system utilizing ten scraped surface heat exchangers is being used to aseptically process and package cheese sauces and puddings into cans. Today, many of these systems are replacing the scraped surface heat exchangers with less expensive tubular heat exchangers. Over the years improvement in the designs of tubular heat exchangers has resulted in these heat exchangers having the ability to heat and cool the same products as the initial systems using scraped surface heat exchangers. Not only are scraped surface heat exchangers more expensive to purchase, but the maintenance cost due to moving parts are much higher than alternative heat exchangers. There are certain problems that are inherent with scraped surface heat exchangers; the most paramount includes the excessive wear of plastic scraper blades and steam-flushed seals. The heat exchange tubes are normally supplied with stainless steel or other corrosion-resistant material, such as nickel, therefore a softer material such as various types of plastics are used for the scraper blades. The plastic blades, particularly at high temperatures, tend to deteriorate and can

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Figure 4.10  Aseptic processing system utilizing scraped surface heat exchangers. (Partial view of a Dole aseptic canner is in the foreground.) (Photo courtesy of AMPI.)

break, resulting in plastic getting into the product. This also causes an increase in overall production cost due to product loss and downtime to resterilize the system. In some cases, when aseptically processing low-acid food products, the scraped surface heat exchange tubes can be chrome plated, allowing the use of stainless steel scraper blades. Stainless steel scraper blades are more effective than plastic scraper blades, but CIP solutions that are usually used to clean the systems are corrosive and can attack the hard chrome plating on the tubes. When the chrome is adversely affected, the stainless steel scraper blades then scrape against the stainless steel or nickel heat exchange tubes allowing abnormal wear and metal getting into the product. Another potential mechanical problem with scraped surface heat exchangers that may lead to sterility problems is with the rotors or mutators containing scraper blades. Some of these rotating shafts are made of stainless steel tubing to which pins were welded and then the blades were attached to the pins. When the welds fail they cause leakage. The shafts then can fill with product that accumulates and cannot be cleaned or sterilized. This bacteria buildup can then migrate into the product being processed. The ability to presterilize this equipment is usually jeopardized and repeated contamination of the product being processed results.

4.2.4.7  Ohmic heating The ohmic heater was developed in the United Kingdom by C-Tech Innovation. The ohmic is a direct electrical resistance heater for food

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products by the passage of current through the product that is being continuously pumped through the heater. The ohmic heater uses electrical current that passes directly through the food product being processed to generate rapid, uniform heating. The liquid and food particulates are both heated at nearly the same rate and unlike the use of conventional heat exchangers, fouling or burn-on of the surfaces of the product piping is eliminated. The ohmic heater cannot be used for all food products. The use of an ohmic heater depends on the electrical conductivity of the food product being processed and on whether the food product is an insulator or a conductor. Food products that are insulators, such as alcohols, fats, and oils, cannot be heated with an ohmic heater. In addition, the ohmic cannot be used to heat water unless some salts are added to the water to increase conductivity. The advantages of using an ohmic heater in an aseptic processing system include: • The liquid phase of the product and the particulate phase are simultaneously heated at the same rate. • There is very rapid heating. • There are no moving parts with the ohmic. • There are no hot heat transfer walls of the heat exchanger. • There are no obstructions in the ohmic, unlike in the use of scraped surface heat exchangers. It is unknown if there are any commercial installations utilizing the ohmic heater in aseptic processing systems, however, considerable research work in ohmic heating is being generated at Ohio State University in Columbus. Ohio State has an ohmic heater installed in the food research facility and has demonstrated that the ohmic heater is a viable alternative to other methods of commercially sterilizing products.

4.2.4.8  Microwave heating A new method of heating food products in aseptic processing systems has recently been developed and commercially installed. The new equipment and technology is using continuous microwave heating to sterilize the food products prior to aseptic cooling and packaging. Industrial Microwave Systems (IMS), based in Raleigh, North Carolina, has developed, tested, and installed a microwave system for use in an aseptic processing system for low-acid, sweet potato puree. The commercial processing facility, located in North Carolina, received a letter of nonobjection from the U.S. Food and Drug Administration (FDA) in February 2008 and began production soon thereafter. The concept was originally proven at North Carolina

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State University by researchers from the U.S. Department of Agriculture’s (USDA) Agricultural Research Services Group, the Department of Food Science, and IMS. The latest commercialized design was recently commissioned at Purdue University where the equipment is installed in its food processing laboratory for testing potential user’s products. Unlike conventional heat exchangers that heat the food by conduction and convection through a hot heating surface, the microwave processor heats the food volumetrically throughout at the molecular level. The microwave energy is provided by using 2450 and 915 MHz magnetrons. As the product is being pumped through a noncorrosive, FDA-approved tube material, microwaves are introduced into a chamber or applicator that surrounds the product to accurately heat it to the desired temperature necessary to affect sterilization. The lack of a hot heating surface, combined with fast and uniform heating of the food product, invariably results in improved product quality with microwave heating compared to conventional surface heat exchangers. Microwave heating can then be combined with other technologies, such as regeneration and tubular coolers, for improved product definition. The use of microwave heating no doubt will facilitate the aseptic processing of food product containing discrete particulate matter. Initial studies indicate that these multiphase fluids heat the particulates at a rate similar to their carrier fluid in a continuous microwave energy field. A diagram showing the pilot plant size microwave heating system is depicted in Figure 4.11.

60 KW Cylindrical Heating System

TEMP. 3 (Exit from 2nd Stage) 2nd Stage Heater Hold Tube TEMP. 2 (Exit from 1st Stage) 1st Stage Heater TEMP. 1 (Product Inlet into 1st Stage)

Figure 4.11  A pilot plant size microwave heating system.

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4.2.5  Continuous holding tubes Aseptic processing is based on sterilization of the food product in the holding tube. The length of time the product is in the heat exchanger to bring it up to the sterilization temperature and the time the product is in any other piping must be ignored. It is the time the product is in the holding tube and the temperature that it is at that time, which is used to establish the safe aseptic process. The accuracy of this time–temperature relationship determines the commercial sterility of the product being processed. Therefore, the control of the product flow or pumping rate at a known consistent rate is vitally important. Once the food and beverages have been heated to the specified sterilization temperature, generally a holding time at this temperature is required to affect sterilization. Holding products at elevated temperature is usually accomplished by having a series of straight, stainless steel, insulated tubes and 180-degree return bends. This is an inexpensive method and a long hold can be provided easily without consuming vast amounts of floor space. Besides inactivation of bacteria, many other events may take place in the hold tube, such as inactivation of enzymes and thickeners hydrolyze to increase viscosity. In addition, many adverse reactions can occur to the product, such as caramelization of sugars, burned odors and flavors, vitamin destruction, color development, and stability changes. Because so many things are happening during holding, care should be taken to accurately engineer and fabricate the holding tube correctly.

4.2.6  Deaerator Deaeration is necessary for aseptically processing many products to remove undesirable air before final sterilization and cooling operations. If the product contains desirable volatiles, as those in orange juice, they may be lost at elevated temperatures. The deaerator may be placed immediately after the supply vessel where the product is at a lower temperature. In other instances, the deaerator is placed after preheating. Air expands as it increases in temperature, and therefore, it is easier to remove the air if the temperature of deaeration is elevated. The removal of air is important for a variety of reasons. The first is that adverse chemical reactions between various components of the product and air can occur if the air is not removed or minimized. The rate of reaction approximately increases as the temperature increases. Therefore, removing air before high-temperature heating is usually desirable. A compromise determines what deaeration temperature is used. The second reason is to reduce fouling of heat exchangers. Air in the product will cause heat exchangers to foul much more than if it is removed. The third

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reason is to maintain constant filling conditions and prevent foaming during filling. If air is present, fills will be erratic and overfilling may be necessary to ensure a minimum amount of product in the container. The fourth reason is to maintain the specific volume of the product. If considerable amounts of air are present, the hold time will decrease. This reduction in hold time may be enough to affect sterilization and result in a spoiled product. If a deaerator is used, it must be fed at a constant rate and the level in the deaerator maintained sufficiently to provide enough head on the discharge pump that will be feeding the timing pump of the system. Many deaerators do not have an adequate length discharge and consequently the net positive suction head (NPSH) on the discharge pump is inadequate and the pump tends to cavitate. This cavitation results in varying feed pressure to the timing pump. Because of this the timing pump will produce erratic flows and filling, sterilization, possibly aeration (as air may be drawn in when the discharge pressure goes from high to low), and fouling can be a problem. With some products, the value of deaerators is questionable. Because deaerators are another item in the processing system that needs to be balanced as far as the flow into and out of it, they should be eliminated in those situations in which their value is questionable. If the product has considerable amounts of air before its introduction to the system, the air should be removed through the application of heat, which will tend to drive it off, or through a vacuum that will physically remove it, or both.

4.2.7  Controls The basis for aseptic processing involves the continuous and rapid heating of a food product to a predetermined sterilization temperature, and the holding of the product at this temperature for at least the minimum period of time to destroy the unwanted microorganisms followed by the rapid cooling of the product to the filling temperature under sterile conditions. It is suffice to say that all areas of aseptic processing and packaging are critical. There is no such thing as almost aseptic, therefore all areas of aseptic processing must be accurately controlled. It is the control of the aseptic processing system that guarantees a successful operation and a commercially sterile product. Controls may be fairly basic and simple, or sophisticated, with each operation being accomplished automatically. As previously stated, “the basis for aseptic processing involves the continuous and rapid heating of the product.” In order to be continuous, the product must be pumped, therefore, pumping is one area within an aseptic processing system that must be accurately controlled. The next step in the definition of aseptic processing is the “rapid heating of the food product to the predetermined sterilization temperature.” Temperature

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is then another important part of an aseptic system that must be accurately controlled. Most often when aseptically processing low-acid food products, the temperature required for sterilization is considerably above that of the atmospheric boiling point. To reach these temperatures, which may be as high as 280°F (138°C), pressure must be induced to the aseptic processing system that will be above the atmospheric boiling point. Therefore, pressure control within the aseptic processing system is vitally important. The product to be processed will generally dictate how the pressure is mechanically induced to the aseptic processing system. Anything within the aseptic process that will jeopardize the commercial sterility of the finished product is critical. From the aspect of overall importance, however, pumping, temperature, and pressure are the three most critical and potentially difficult areas of aseptic processing to control. It is vitally important that the final temperature at the end of the holding tube to which the product is heated be set, indicated, and continuously recorded. The sterilization product temperature should be sensed and validated with a high-quality sensor that is often calibrated. The controlling instrument may be electronic; however, a transducer is used to convert the electronic output of the instrument to the pneumatic actuation of the valve. It is important that the sensors used with the indicating and control instruments be connected to the instrument in the proper manner. The electrical lead should be an extension wire of the type that is compatible with the sensor and the controlling instrument. The temperature at the end of the aseptic processing system should be recorded, at least when the system is being initially presterilized. It is important that this point be at the minimum temperature for a minimum period of time to ensure the equipment, piping system, and valves are sterilized. Controlling preheat temperatures automatically is desirable so the temperature of the product entering the final heater will be consistent. The preheat temperature will affect the final product temperature and govern the water or steam temperature used for final heating. If the product is an acid product, and a system incorporates a provision for idling, the water used must be acidified to the pH of the product or lower. If this water is not of the proper pH and the switch is made from product to water, a chance for contamination exists. Therefore, the pH of the water that will be used must be recorded and controlled at the proper level. If it is not at the set pH, the system should divert sterilized product from the filler and be interlocked so product cannot enter the system. The production flow rate of the system must be set and locked such that any unauthorized personnel may not alter the flow rate. Additionally, the system should be interlocked so if the sterilization temperature and time are not met, the system cannot go to the forward flow position and be filled.

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4.2.8 Aseptic surge tanks, barrier seals, and automatic air-operated valves 4.2.8.1  Aseptic surge tanks Aseptic surge tanks are used to balance the flow from the processing system to the demands of the packaging equipment. Most often aseptic surge tanks are used to process products that will be adversely affected by recirculating and reprocessing. Dairy products are a good example. Reprocessing dairy product generally results in caramelizing of the milk solids and development of off flavors. Generally, aseptic surge tanks add no value to the product; they are an additional means of potential contamination, and they are initially very expensive to purchase and operate due to the sophisticated controls necessary to sterilize and maintain sterility in these vessels. Aseptic surge tanks should be avoided if possible. Aseptic tanks are most generally used with low-acid products and are therefore ASME vessels designed for higher pressures. Sometimes aseptic surge tanks are used with acid products and non-ASME coded tanks. Regardless of the pressure rating, the tank must first be sterilized, which is often done with steam. The steam pressure and temperature are held for a minimal period of time. The steam backflows through filters, which may be connected to an incinerating system to provide particle-free air. After sterilization the tank is cooled. Cooling may be done with air (gas) or water in the tank jackets. If air is used as the cooling medium it must first be sterilized, usually by filtration. The cooling operation is critical because steam that is in the tank condenses as the temperature is lowered and the pressure is reduced. Positive pressure must be maintained during cooling to prevent contaminating microorganisms being drawn into the tank from the atmosphere. This pressure is maintained by air or gas that has been sterilized either through a filter or filter–incinerator combination. The pressure is controlled so the maximum pressure desired in the tank is not exceeded. Potential points of leakage include flanges, connections, and agitator shafts (if the tank is agitated), which are flushed with barrier seals. If the product being held is not heat sensitive and will not burn, steam is used as the barrier medium, and temperature and pressure can be measured. If the product is heat sensitive, steam is usually used to initially sterilize potential points of leakage followed by a bactericidal solution such as a peracetic acid, hydrogen peroxide, iodophor, or something similar. Any contaminants that try to enter the tank must move across the barrier unless the tank has a leak. Usually, aseptic tanks are insulated because they can be quite large and are excellent radiators. Insulation prevents the tank from heating the area and requiring an extra large boiler to heat the tank to sterilizing

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temperatures. If the product to be stored in the tank must be kept cold, the tank will have a cold-wall surface for cooling with tower or refrigerated water. Pressure in the tank is often used for discharging the product after the tank is cooled. With some products, a pump may be used to unload the tank. This generally is an added expense that is not normally required. If the product in the tank is oxygen sensitive, nitrogen may be used in place of air to push the product from the tank. The tank should be sterilized with culinary steam that passes through a separator and purifier per recommendations published by 3A. Residuals of the steam that contact the product zones of the tank may stick to the walls of the tank and later become part of the product. A certain amount of air or gas used to maintain or build pressure in the tank is absorbed at the interface of the product and the gas. Consequently, lines feeding the air or gas, filter housings, and pressure control valves should be stainless steel of sanitary design, and they should be regularly cleaned.

4.2.8.2  Barrier seals Barrier seals are necessary to separate contamination from product that has been commercially sterilized. They are necessary for any moving parts in the sterile zone and to keep contaminating bacteria from a vacuum vessel or anywhere the sterilized product is at a lesser pressure than the surrounding area. Barrier seals should have a space sufficient to allow the flow of sterilizing media. If the item to be sealed is the plunger of an aseptic homogenizer or a valve stem of an air operated valve, the sealing distance (barrier) should be greater than the stroke of the pump or of the valve. In this way no portion of the plunger or valve stems that are in the sterile zone ever move to the atmosphere and become contaminated. Pump plungers and valve stems can move faster than contaminants can be sterilized, therefore, the seal area needs to be of greater length than the stroke. Any portion of the plunger or valve stem that moves must travel from the sterile product zone into the seal area only. The plunger or valve seal cavity must initially be sterilized with heat that can be conducted to all portions, including the areas between gaskets and sealing flanges, and in cracks and crevices. Heat can travel to these areas and sterilize them. After heat from steam or water is used to sterilize the area, it can be maintained in a sterile condition by chemicals. This technique is used with heat-sensitive products, for instance, liquid eggs and dairy products, which tend to burn or denature when heat is applied.

4.2.8.3  Valves Aseptic valves have been developed as aseptic processing and packaging has evolved. Initially, aseptic processing systems were used with

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Dole aseptic canning systems and the aseptic valves that were used were furnished with the Dole aseptic canning system. These valves were a combination, primarily, of hand-actuated piston-type valves that were maintained sterile by enclosing them in the filling chamber, which was maintained at 265°F with superheated steam. Hence, the main requirement of the valves at that point was to be able to take this temperature. Because of this requirement, most of these valves had metal-to-metal seats and the use of elastomers was limited. The routing valves, which were initially used on the Dole canners in either tee or tee-tee, were piston valves. These valves were used to direct the product to a filler, aseptic tank, or the drain supply. The concept used with these valves was having the piston in a barrier material, such as steam, and the barrier was of greater length than the stroke of the valve. Hence, no portion of the valve that was sterile ever moved to the contaminating atmosphere. These valves were available with barrier seals on the connections so if the valve was applied where a vacuum existed, any contaminant that was drawn into the sterile area would first have to move through the barrier. The product was sealed from the barrier with a sanitary seal and the barrier was sealed from the atmosphere with an O-ring seal. Hence, a double seal existed and leaks did not occur. One of the disadvantages of using a barrier such as steam was if the flow of the product was small, the steam would cause the product to increase in temperature. This increase in temperature was several degrees. In addition, because the flow was minimal, the product would burn to the hot barrier surface; hence, with heat-sensitive products such as liquid eggs or milk, the barrier was first sterilized with heat and then the barrier material was changed to a cool liquid sterilant. This sterilant was effective against any organism that entered the zone; however, it could not sterilize between gaskets and the sealing surface or cracks and crevices that may have existed. As systems became more complex and more sterile valves were required, the number of barrier seals became excessive. A system with a number of seals was complicated. Also, in order for integrity to be guaranteed, the failure areas all had to be interlocked. This further complicated the piping system and the control system that was used. Piston valves were equipped with diaphragms so as the piston moved up or down, the diaphragm flexed when the stem moved, and no barrier seal was required. This appeared to be satisfactory; however, the valve would be actuated at high temperatures (up to 300°F) and low temperatures (40°F), and materials that could withstand a number of cycles under these conditions did not exist. Hence, the early design and materials were not satisfactory. As time progressed and new materials were developed, along with different designs, this situation improved. Today reliable valves are available.

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One of the most logical ways to provide a flexible diaphragm is to use a diaphragm-type valve made of stainless steel to sanitary standards where the diaphragm is made of high-grade materials. Initially, the major manufacturers of diaphragm valves did not make stainless steel versions with diaphragms approved for food handling as they do today. The diaphragms are quite reliable and will withstand a number of cycles and varying temperatures; however, the diaphragms should be changed on a regular basis. Certain users of these types of valves have gone to the point of using sterilizing solutions on the top of the diaphragm to guard against such failures such as pinholes or cracks. If a failure occurs, then leakage is to the sterile material from the sterilizing liquid, such as Oxonia or iodine. The use of aseptic processing techniques has escalated rapidly in the pharmaceutical industry, and development efforts by valve manufacturers have increased to satisfy this demand. In the future, improved materials and designs are anticipated for larger sizes as needed by the food and dairy industries. At the present, piston-type valves that are normally used in the food industry are available in 1½- to 4-inch sizes. Diaphragm valves are available in ½- to 3-inch sizes.

4.2.9  Homogenizers Homogenization reduces particle size by subjecting the product to high levels of shear. Shear is usually directly proportional to the pressure, or energy, used to create it. Milk, ice cream mix, and certain other dairy products are homogenized to reduce the size of the fat globules, whether the products are sterilized, then aseptically packaged, or pasteurized. If high pressures are used, homogenizing the product in a pasteurization system that is not part of the aseptic system is desirable. Aseptic homogenizers are expensive to purchase and maintain, and are potentially contaminating devices (Figure 4.12).

Figure 4.12  A typical homogenizer.

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The general design of aseptic homogenizers is to flush the pistons with steam in a chamber that is of greater length than the stroke of the piston. In this manner, no portion of the piston that is in the sterile zone ever gets to the nonsterile atmosphere. Other portions of the homogenizer that will be modified include the pressure-adjusting stems used with the homogenizing valves. Again, the adjusting valve stem is in a chamber that is of greater length than the stroke to ensure no portion of the valve stem used for adjusting the pressure is exposed to the atmosphere. With certain heat exchangers, such as HydroCoils, containing high pressures in the several thousand-pound range is possible. Sometimes, if the pressures to be transmitted are relatively low, a remote homogenizing valve is used. By using a remote valve, the homogenizing operation can be accomplished after the product is heated and cooled to a point at which thermal development of viscosity will no longer take place. The viscosity increase that has developed can be reduced by shearing the product at fairly low pressures (500 to 1000 psig). Some manufacturers make systems for sterilizing dairy or dairybased products that incorporate homogenization on the sterile side. This is done to make total processing of the product the most economical (equipment costs are minimized). In this manner, when the product is being heated-held-cooled for sterilization, it is also homogenized, much as it would be in a conventional pasteurizing system. As indicated, the aseptic homogenizer is more expensive to purchase and maintain, and it is a concern if there is ever a question regarding sterility. If a remote homogenizing valve is used and the pressure exceeds 1000 psig (which is the published safe operating pressure for CIP clamp-type fittings), then high-pressure hydraulic-type fittings must be used.

4.2.10  Ingredients Usually, if a raw product is used, such as milk, juices, or creams, the quality of the final product will be no better than the raw product. In other words, if the raw quality is good, the final product can be good. If the raw product is poor, the final product will be poor. The raw product must be received and stored properly before its use in the aseptic processing and packaging system. If the product is of dairy origin, such as milk or cream, the product may be raw or it may have received minimal heat treatment before its receipt in the aseptic processing and packaging plant. With dairy products the raw product should be examined for quality using conventional tests identifying the number and types of bacteria present, acidity, and pH, and physically examined for color, smell, and sedimentation. If the raw product is not of the desired quality, it should be rejected. If the product quality is satisfactory, it should be stored in clean tanks,

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which should be refrigerated. By doing so, microorganism growth and enzymatic activity will be minimized. Often, enzymatic changes cannot be detected using conventional testing methods used in production plants. Further, microorganisms can produce various enzymes that will increase in number as time of storage increases. The result of a product that has excessive enzymatic development will vary from fouling of the heat exchangers, meaning the aseptic process may be shortened, to stability problems, when the product may separate, coagulate, or become “sandy” during storage. In addition, the finished product may prematurely develop off flavors or other undesirable characteristics.

4.2.11  Clean-in-place (CIP) Proper cleaning of equipment in an aseptic processing system is vital. Otherwise, there is a question whether it has been sterilized during the initial sterilization procedure. Although the sterilizing temperature may have been obtained, if the system is not properly cleaned, sterilizing it may be impossible. The CIP system does not have to be sophisticated and interlocked; however, if cleaning efficiency is determined through manual inspection, or by observing charts, thermometers, and gauges, then an exact procedure must be established followed with records being provided on a daily basis to ensure cleaning is being accomplished. If cleaning is being accomplished by a sophisticated system that delivers cleaning solutions at desired temperatures to the process system that is to be cleaned, the system should be inspected regularly after CIP has been completed. This inspection should be made of the most difficultto-clean components in the process system. During this inspection, the equipment, pipelines, and valves can be examined to ensure they are operating properly, and do not have any cracks or crevices, or gaskets that should be replaced. Gaskets should be taken from joints regularly, inspected, cleaned if necessary, and replaced if bad. It is important to realize that automatic controls with sensors can indicate, control, and record items such as pressure, temperature, and pH. However, they cannot look at a gasket and determine whether it needs to be replaced or cleaned, or whether it is hard and brittle. Therefore, it is important that a program be established to inspect critical points at regular times to verify that they are correct.

4.2.11.1  Clean-in-place solutions CIP solutions are normally made by adding certain chemicals to well or city water that may or may not be filtered or treated. If the water

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used is very hard or contains numerous minerals, excessive cleaning compounds must be used to adequately clean the equipment in the system. If the strength of the chemicals is excessive, reaction between these chemicals and the stainless steel of the equipment will proceed at a much faster rate. The equipment will deteriorate and will need to be replaced at more frequent intervals. Also, many cleaning chemical companies use halogens, perhaps chlorine, to enhance the ability of the chemicals to clean. A compound such as chlorine will react with soil and do an excellent job of cleaning. Unfortunately, it also will cause stainless steel to corrode and fail. This is accentuated at the elevated temperatures that are often used in the CIP cycle. If difficult-to-clean products are being processed, such as liquid eggs or dairy products, the CIP cycle may be extended and may be at elevated temperatures. This further suggests the need for stronger CIP solutions that attack the stainless steel and cause it to fail that much faster. Probably the best approach is to prepare CIP solutions from high-quality water that is low in mineral content. This may mean using distilled or reverse osmosis (RO) treated water. Often, the cost of supplying water of this type will be returned many times over. If the equipment is not properly cleaned, the questions of how dirty it is and whether the initial sterilization cycle is adequate for sterilizing dirty equipment must be addressed. Therefore, equipment should be examined after cleaning to verify the CIP cycle has been adequate. The design of the equipment should be assessed to verify it can be cleaned by CIP, and the CIP cycle should be done at regular intervals, and the CIP solution should be as weak as possible to do the job. Heating of the CIP solution should be by the CIP system, not the heat exchangers in the aseptic process system. Heating with the equipment in the aseptic processing system may cause films or precipitated minerals to adhere more tenaciously to the heat exchange surface and cause cleaning to be less effective. The results are the CIP cycle must be longer, which will have a greater negative effect on the equipment, or the CIP solution must be stronger or hotter, which can also cause problems. This whole subject of CIP solutions, the type of solution that should be used, the duration it should be used for, and the temperatures that it can be used for, is very involved. However, suffice to say this is a subject in itself, and competent individuals should be involved in this portion of the operation to make sure the CIP system is properly designed, proper chemicals are used, proper cycles are established, and inspections are done regularly to verify that the results that are being obtained are those wanted. It cannot be emphasized enough that the quality of the water, and steam if added directly to the CIP vats, has a significant effect on the CIP solutions and cycles required.

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4.3  Plant layout considerations 4.3.1  Preparation and processing equipment and systems As with any food processing plant, the heart of the plant is the processing and packaging equipment. The objective of the processing/packaging system is to render the product to its final shelf-stable state. Processing is usually in a closed system so contaminants cannot enter after the product has been sterilized. Possible contaminating devices, such as deaerators, timing pumps, and preheaters, are often located away from the sterile segment of the packaging system to help maintain desirable bacteriological conditions. In most processing facilities, the preparation equipment, such as mixing and blending equipment, raw supply tanks and CIP equipment are in one room that is physically separated from the sterile processing area by a wall or air curtain. The sterile processing equipment, including the heaters, holding tubes, and coolers, are in another room where the desired bacteriological quality is maintained. This is done through filtered air that is at a positive pressure, and the air is changed often (at least 20 times per hour) to ensure clean conditions exist.

4.3.2  Packaging system area (bacteriological conditions) Certain aseptic packaging equipment is designed to withstand highly contaminated areas where moisture, food products, contaminated air, and filth may be present. An example is the Dole aseptic canning system that uses superheated steam. The superheated steam is at such a temperature that contamination can be eliminated by killing the causative microorganisms. The Dole system assumes the metal cans (which are heated with superheated steam) will be “clean and dry.” Usually, the cans are inspected either visually or with an electronic device to verify their sanitary condition. The cans must be dry and must not be transferred through an area where moisture-laden air exists. If moisture is present, the cans may not be sterilized. Superheated steam (which does not contain much heat) will be used to convert the moisture to steam, and the temperature of the can will not be as high as what has been assumed (it is not measured) and is required for sterilization. If the condition exists where moisture is present, the product packed may not be sterile. One way of ensuring the containers do not have undesirable contaminants is to have them travel through an area where the humidity is controlled. Air systems that control the temperature, humidity, and bacterial loads by filtering the air are available as commercial items from many companies and should be used. The use of flexible aseptic packaging depends upon the packaging material being in very good condition from a microbiological standpoint

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before it is sterilized and filled, which may include forming if a form– fill–seal system is used. Most systems use chemicals such as hydrogen peroxide, peracetic acid, or chlorine spray alone or possibly with heat to cause the chemical to change form and dry. Usually, the heat is not sufficient to sterilize the packages or to flow into cracks or crevices that may exist in the packaging machinery or the packages themselves. In the case where hydrogen peroxide is used as the sterilizing chemical, most of the sterilizing action occurs when the hot air causes the hydrogen peroxide to change to water vapor and oxygen. Considering that most chemicals are not strong sterilants, it is recommended that this type of aseptic packaging equipment be installed in a very clean area, which could be classified as a Class 1000 Clean Room or better. A clean area or clean room must be maintained in a clean condition by designing the facility so it can be readily cleaned and possibly treated with a bactericidal solution. Utility pipes, such as those that may be required for tower or cold water, should be insulated, otherwise, condensate may form on them, which will tend to collect airborne microorganisms. If such condensate should get in the packaging machinery or on the packaging material, the sterilization process may not be adequate. Traffic from personnel or lift trucks and conveyors should be minimal, and ideally the facility should be designed so such traffic does not exist. Maintenance should not be accomplished during aseptic packaging operations to reduce the number of microbiological contaminants in the area. The temperature, humidity, and microorganism level in the facility should be checked regularly, and standards should be adopted that have been proven satisfactory for a successful operation. Raw materials for packaging should be brought into the room or facility through sealed conveyors and equipment should be arranged so that packaged product is discharged or moved from the area without adding excessive numbers to the microbiological load. After the product is packaged, it should be warehoused and the production or packaging lot cleared by quality control to verify it is satisfactory from a bacteriological standpoint. This area should be maintained at room temperature or below. If the product is a “long-life” product, the area should be refrigerated at 45°F or below. The warehouse area should be as far from the packaging area as possible and in the vicinity where the delivery trucks or vehicles can be loaded and unloaded without increasing the microbiological numbers in the packaging area. Providing samples that can be evaluated by the end user before accepting a container of commercially sterile product may be desirable, particularly with large packages. Large packages, such as 200- to 300-gallon tote bins or bags, may represent the product in the first, middle, and final portion of the package. The warehouse used to store this product must be

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arranged in such a manner that the product can be readily removed and shipped to the consumer once the lot is accepted. Particularly with large packages of several hundred gallons, the stresses placed on seals, and valves that may be sealing the product, are much greater than what would exist with an individual portion. Therefore, the physical arrangement should be such that seals, packaging materials, valves, and flanges are not disturbed when the product is being moved from the warehouse to the vehicle transporting the product to the user. For many products, such as liquid eggs, citrus products, and certain dairy products, it is mandatory that the warehouse be refrigerated. This is a precaution to maintain the maximum quality of the product from a chemical standpoint so that undesirable flavors, odors, and colors do not develop, and vitamin retention is at a maximum. The viscosity of the materials is also critical and is affected by storage at cooler or cold temperatures. Some products, such as flavors or fruits added to ice cream or yogurt, should be at 45°F or below, so they will not warm the product when added to it. However, viscosity at these temperatures must be considered, and it must be determined whether the product can be removed from the container. If product is not cooled to the final room temperature, cooled “stack burn” can result if the product is not placed in the warehouse so cold air can circulate and cooling in the package can take place rapidly. Products have been placed in warehouses that reach extremely high temperatures and the product literally continues to cook. This is particularly true if the product is stored at elevated points in the warehouse, and the warehouse is not refrigerated.

4.4  Utilities 4.4.1  System sterilization water Water used initially to sterilize the system must be of high quality from microbiological and chemical standpoints. It should be low in microorganisms and not contain spores that will be difficult or impossible to sterilize. It must be considered that some of this water will stick to the surfaces of the equipment used to sterilize the product. After the water has been transferred through the heating units, it will move to the other downstream equipment and be used to sterilize it. The process of initially sterilizing the equipment consists of continually circulating the water and increasing the temperature as it moves through the system. The equipment at the end of the system will be lower in temperature than the water discharging from the heater. If the water or equipment has numerous microorganisms in it or if the microorganisms are very heat resistant, they

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may not be sterilized. This is of particular concern when acid products are sterilized. The temperatures used during initial sterilization are lower and surviving organisms may grow if the pH is high enough so the condition is nonacid, or organisms in cracks or crevices may survive if they are not contacted with the sterilizing water. To improve the quality of the water from a microbiological standpoint, it can be filtered before use. If the system has equipment downstream of the final heater that have a large number of cracks or crevices in them, such as an aseptic homogenizer, certain types of heat exchangers, or valves, heat-resistant organisms may be trapped and lodge in difficult-to-reach areas. These phenomena have happened on occasion when the heat present during the sterilization cycle was not adequate to penetrate all the difficult-to-sterilize areas. If the initial sterilization process is minimal, survivors may contaminate the product during processing. Another concern is that the water may contain various minerals that adhere to the surfaces of equipment. After sterilization these minerals can slough into the product and cause the product to be of a different chemical makeup than that desired. Varying adverse qualities can result, including flavors, viscosities, and color changes. Also, if the water contains particular chemicals, it can form a film on the heating surfaces that causes fouling prematurely and a shortened operation result. Fouling can be caused by many factors, but it often starts with buildup on the surface of the equipment. One technique used to reduce fouling is to flush the surface after sterilization with water that contains a food-grade acid. The acid tends to remove the precipitated minerals and make the heat exchange surface clean. By doing this it will allow for a longer operation before fouling occurs.

4.4.2  Preparation water Water used in the preparation of product is of concern because it may contain undesirable minerals or have excessive bacteriological loads. These factors can cause the product to be off quality and possibly have bacteriological numbers that are excessive and can survive the sterilization process. Filtration can help by removing microorganisms to a tolerable level—assuming proper filters are used. Reverse osmosis, or ultrafiltration, can remove certain chemicals that may make the water tolerable considering the chemical characteristics wanted. Other approaches are to use pure distilled water that does not have chemicals. Water from a municipal source is often treated with chemicals such as chlorine or fluorine. These chemicals may or may not be tolerable and allow production of the product with the characteristics wanted. Sometimes, formulas are developed in the research lab using distilled water, and yet they are produced in a plant using city water and a different product(s) result. Of particular concern is the use of municipal

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waters if the chlorine or fluorine level varies. Although the target level of certain compounds, for example, chlorine, may be 1 ppm, the level may vary between 0.1 and 5 ppm. This can affect the chemical characteristics and qualities of the product. It can also cause other undesirable results, from fouling of heat exchangers to premature failures caused by chemical attack of the stainless steel or other materials used in the manufacture of the equipment. Therefore, the water used in the preparation of formulated products should be analyzed to verify it is of the quality necessary to produce the product wanted. Other problems can result if the water chemistry is not correct as the heating process can cause a film to develop that is extremely difficult, if not impossible, to remove using conventional CIP solutions. Special CIP solutions may have to be used occasionally. For example, a CIP solution may have to be used every week or two that will remove this film. Usually such solutions contain acids and will dissolve salts that have precipitated on the heat exchange surfaces. These salts may be the result of the water used to prepare the formula.

4.4.3  Heating/cooling water Water is used in certain types of heat exchangers for heating the product for several reasons; the temperature can be more accurately controlled than steam; and it does not vary in temperature because valves and traps are opening and closing. It also contains more Btus in a sensible heat form than steam, considering both sensible and latent heat if the pipe carrying the water is a minimal size. This is true once the pipe is larger than 2 inches. If the water used is in a closed circuit, generally, undesirable chemicals will be precipitated in the first few minutes and the water will be fairly inactive chemically. If the water is used for a single pass and then is used for another function in the plant, such as CIP or rinsing and cleaning raw products, minerals in the water can stick to heat exchanger surfaces and a film will develop. After a period of time the film can become so great that cooling is impaired. This often happens in high-temperature coolers if the water is not maintained at the proper pressure. If the pressure is not regulated above the flash point, then salts in the water precipitate on the heat exchange surface and cooling is impaired. Additionally, the salts may react with the metal of the heat exchanger and cause it to fail. This can be a particular problem if well water is used as a single-pass coolant and the pressure on the water is not adequate to prevent flashing. If tower water is used as a coolant, two concerns exist. One is that the chemicals used in the tower may be harmful to the equipment being used, and, second, is the bacteriological loads that may exist. Some tower water, particularly in high ambient temperature areas, have a very high

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bacteriological content. If this water ever gets to the product it can cause contamination. It could get to the product because of a pinhole or stress crack in the heat exchanger or through a gasket. Sometimes tower water is treated with a bactericidal agent to keep microbiological growth within reasonable levels. However, the compounds used to control the bacteriological level are often harmful to processing equipment, in that they will cause chemical reactions between the chemical bactericide and the stainless steel. Tower water, if used with thin-wall heat exchangers or gasketed joints, should be filtered before it is used to ensure the microbiological levels are low. It should be determined that any chemicals used will not cause the process equipment to corrode. The system used to circulate the water should also be arranged in such a manner that adequate pressures always exist and “flashing” does not occur. The use of tower water coolant is perfectly logical; however, the system for using the tower water must be designed and operated properly. Another consideration with the use of tower water is that it should be removed from the heat exchangers when they are initially sterilized by using an “air blow” or by pumping it back to the tower. By using this process the chemicals added will not be lost.

4.4.4  Refrigerated water Refrigerated water usually comes from one or two sources. It may be produced in an ice bank, which is a common technique if the process is only operated for part of each day. The other method is to use a continuous heat exchanger, such as a shell-and-tube, which uses a direct-expansion refrigerant, such as ammonia, to cool the water. Often, the equipment used to cool the water is not sanitary and cannot be adequately or properly cleaned. Bacterial buildup can be significant and contamination can result if the aseptic processing coolers were to leak. It must be considered that cooling water can leak into the product although the pressure of the product may be higher than the cooling water. Venturi effects can literally suck the water into the product although the pressure (product) may be several pounds higher than the water. This problem is increased if a pulsating pump is used to drive the product through the heat exchanger. If the pressure varies, although it may be higher, pulsation on the bacterial cells or spores causes them to be drawn into the product leading to contamination. It must be remembered that bacteria will move and grow against high pressures, and pressures must be exceedingly high (100,000 psi or more) to inactivate them. Even high pressures in the 100,000-psi range will not inactivate certain types of bacteria, enzymes, or spores. To protect against bacterial contamination, refrigerated water should be filtered before being used in the cooling heat exchangers.

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Aseptic processing heat exchangers should have thick walls and be arranged so that stresses either during initial sterilization or processing can be withstood and cracks do not develop. Thick walls of 316 or 316L stainless steel are probably the best impediment to the formation of pinholes.

4.4.5  Steam Steam is used in many areas of aseptic processing and packaging plants. It is used in the preparation of the product by heating it indirectly through the wall of a preparation vessel or by direct addition to the product being prepared. It is used for sterilizing equipment used in processing or packaging operations, for sterilizing seals, and for maintaining a sterile atmosphere in the seal area. It is also used for developing heat that causes sterilants to vaporize or breakdown, such as with hydrogen peroxide. The steam that is used indirectly to heat the product through a heat exchanger wall that will heat water, which in turn is used to heat the product, or used where it will not become a part of the product does not have to be culinary or pure. If the steam is used to directly heat the productcontacting surface, for instance, the wall of a tank, it should be culinary per 3A definition. This definition requires that no boiler compounds can be used that are not listed or will cause the product to deteriorate or react negatively and generate off colors, have off flavors or odors, or be harmful to the consumer. If the steam becomes part of the product, such as in the preparation or sterilization process, then it should be produced from a reboiler that is sanitary and the steam should be made from distilled water. Not only are there possible regulatory implications, but the product itself may develop undesirable characteristics from the chemicals that may be in the steam. These chemicals may not be harmful to humans, but they may cause undesirable reactions to occur between the product and the steam. Steam generally should be at least ideally 150 psi at the boiler. After the steam travels through the various distribution lines and headers, it may be at a reduced pressure at the use point. At the use point it should be regulated at a constant stable pressure of 125 psig. From the constant 125 psig, the steam can be controlled to the desired use pressure whether it is in a preparation vat, heat exchanger, aseptic tank, or packaging machine. If the pressure fluctuates, degrees of superheat can vary and cause the heat content of the steam to vary, and the final temperature of the product can vary. Steam should be treated in such a manner that superheat is removed. One condition that exists when steam is used to heat products is that as the control valve opens and closes, the temperature of the steam entering the heat exchanger varies. This will cause the temperature of the heated product to vary. A better way of heating products is to use hot water as the heating medium. This is particularly true with indirect heat

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exchangers. Opening and closing the steam valve and trap tends to minimize temperature fluctuations and hot water is more likely to maintain a constant, or very close to constant, temperature. When hot water fills a pipe, the number of Btus carried in the hot water in a sensible heat form is greater than the number of Btus that can be carried in the same sized pipe with pressurized steam, considering that pressurized steam contains both latent and sensible heat. This is one reason that hot water is used to initially sterilize large aseptic processing systems. Because more Btus can be carried, the time that it takes to heat the equipment on the sterile side of the system to the sterilizing temperature is less and the total cycle time is reduced. Regulations in certain areas now require that steam added to CIP solutions be filtered. Actually, this steam should be culinary per regulatory requirements or 3A recommendations because there is a chance the chemicals in the steam may be left on the heat exchanger or pipeline walls.

4.4.6  Air Air is used in several applications in aseptic processing and packaging facilities. For instance, it is used for instruments where the normal pressure requirement is 20 psi. Most instruments today are electronic and require a transducer to convert the electric signal to a pneumatic signal to actuate steam valves, directional valves (sanitary), or solenoid valves. Directional sanitary valves normally require between 60 and 80 psi air for actuation. The air used with steam valves, routing valves, and solenoid valves should be clean and dry and should be purified so particles are not present that cause the valves to improperly operate. Air used with instruments or valves should have the moisture removed and should be filtered to remove particles. Moisture removal is normally done with a dryer or it can be a filter that removes small amounts of moisture as air passes through it. A coalescing filter is used for this purpose. To remove particles, various filters are used that are generally rated at some efficiency level for a given size of a particle and the volume of gas they will pass at a specified pressure. Because filters for air or other gases are different from filters used with liquids, they should not be interchanged and used for both purposes. If the compressor is an oil type that produces significant quantities of oil (which ends in the air), then this should be corrected or changed. The oil used to lubricate compressors is not the same type that should be used for lubricating instruments or directional valves. Usually, the oil from the compressor is removed in a second type of filter, or an oil-removing device, which usually uses carbon as the absorbing agent. If the compressor is in a condition such that the amount of oil passed is significant, using

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an absorber that can handle large quantities may be necessary. Air used in direct contact with the product, such as air used to agitate tanks, should be clean and sanitary. This means a filter that has smaller pores than filters normally considered satisfactory for filtering the air used with instruments or valves should be used. The air should not contain any lubricant (oil), water, or particles. The air should be transferred through lines, filter housings, and control valves that are sanitary and can be cleaned. It must be noted that the air is actually part of the product or will become part of the product. The lines and equipment transferring and controlling the flow of air to the product must be clean and treated just as if they were a product line. If a product contains sterile gases that are part of the product when it is packed, such as a mousse or other aerated product, it must be sterile. Sterilization of gases is done using filters, preferably in conjunction with incineration. If only filters are used at least two sterilizing-grade filters should be used. It is very difficult to tell whether a filter is operating correctly until after a lot is processed, which may be very expensive. The use of filters must be incorporated in the design and particles, not only those that carry bacteria, but other undesirable particles must be removed. Incineration systems are used with filters to provide a record of the temperature to which the gas has been heated for sterilization. This temperature must be chosen so it is adequate for sterilizing the gases, considering the product into which it will be injected. Sanitary air systems used for delivering air to products should not only be made of stainless steel and sanitary, but should also be cleaned and inspected regularly. Filter housings, pressure regulating valves, and on/ off and modulating valves are available today in stainless steel of sanitary design. These components, along with the distribution system, should be cleaned just as the product lines and control valves in the product distribution system. Usually, the air-handling system should be considered sanitary from the discharge of the check valve of the air-producing system, which is probably nonsanitary (compressor, receiver, dryers, etc.), through the sanitary portion, which is the distribution system, pressure-regulating valves, on/off valves, and lines. The air system from a sanitary point should be designed in a similar manner to the product-handling system so it can be CIP.

4.5  Filters 4.5.1  Gases Filters used in aseptic processing and packaging systems generally fall into one of two classes: one class is filters applied to gases; and the second class is those applied to liquids, such as vitamins, chemicals, flavors, colors, and enzymes. Generally, filters used for gases are designed to remove

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undesirable constituents from the gases. This could include oil, water, undesirable odors and vapors, and particles. Filters that are meant to pass gases are made of many different materials that may or may not withstand in-line sterilization. Those element constituents that do not necessarily hold up well to in-line sterilization where steam pressure up to 100 psig or more may be experienced should not be designed into the system. Coalescing filters, charcoal filters, and prefilters are usually made of heatsensitive materials, and they will not withstand steam or sterilizing temperatures, and should not be in that portion of the system where steam will be prevalent. Sterilizing-grade gas filters normally use borosilicate-type elements that can pass steam through the element without damage. Borosilicate is a hygroscopic material, meaning it will not pass water; therefore, the filter must be arranged in the system so that as steam contacts the element it is on the outside of the cartridge rather than on the inside. If steam contacts the inside of the element, condensate will be formed and it probably cannot move through the element. Therefore, after a few cycles the cartridge will fill with condensate, be exposed to sterilizing temperatures and pressures, and fail prematurely. If the steam is on the outside of the filter, condensate will form, and can be trapped off without doing damage. The temperature of the condensate must be adequate for sterilization. The gas can be either on the outside or inside the cartridge as it will pass through the element without damaging it. The sterilizing-grade element can be formed in either a pleated or round circular version. The pleated version has the advantage in that as the temperature increases during sterilization, the pleats expand, much as the pleats in an accordion. This results in minimal stress. However, if the cartridge is not pleated, and only a round circular element is used, expansion must be accommodated in the element and the metal band holding the cartridge at the top and bottom. After a few cycles, stresses at these points develop to such a point that the filter will fail and leakage will occur. Filter elements can be tested with a smoke-type tester. In essence, this unit produces black smoke that is directed to and contained in the filter element unless there is a leak. If there is a leak, the black smoke escapes through the crack or hole. Steam filters are normally in stainless steel housings and are made of elements formed from sintered stainless steel or woven stainless steel mesh. These elements usually have a size rating of 25 to 1 μm. When the element becomes clogged, it can be removed, hosed off, or cleaned manually, and replaced in the housing. It can be reused often in this manner. Sterile-grade elements, coalescing elements, and charcoal-impregnated elements cannot be reused. Therefore, because elements of sintered stainless steel are available to 1 μm, they are often used as prefilters for sterile gas systems as well as steam filters.

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Prefilters are normally 25 μm or larger. They remove most of the large particles from the gas, so the fine-grade filters do not have as large a job to do. They not only remove particles, but they can also remove a certain amount of moisture, oil, and even odors. Therefore, systems may be designed with a steam-grade filter as a prefilter followed by finer-grade filters to remove smaller particles that exist in the gas system. If the gas is air and the air is produced by an oil-type compressor, the air filtration system should include a coalescing filter to remove moisture, a charcoal-type filter or absorber to remove oil and oil odors, and two sterilizing-grade filters capable of removing particles down to 0.015 μm (a standard size). As indicated, all the filters except the sterilizing-grade filter that contains a borosilicate-type element, should be in the low-pressure/temperature side of the system.

4.5.2  Liquids Liquids are filtered, primarily, with depth-type filters (although they may be in a cartridge form) that retain the particles that are in the liquid. Usually, they are rated to 0.2, 0.45, and 1.0 μm. This is the maximum size of most organisms that will be in a liquid that must be kept out of the sterile product. Liquid filters will not filter out flavors, colors, viruses, or similar materials that are smaller than 0.2 μm. Many liquid filters are made of fairly heat-sensitive materials, for example, polypropylene or cellulose acetate and will not take above 250°F or 15-psig steam. They are often sterilized in a laboratory autoclave where they are not subjected on one side or the other to high pressures. They are generally used for sterilizing using nonthermal means. They are used extensively for purifying water, or other liquids, which may be used in the preparation of a material. The use of liquid filters in an aseptic processing plant is a judgment decision that is based upon the quality of the liquid to be used. If the liquid is of questionable quality or is to be used in a critical operation, then it should be filtered.

4.5.3  HEPA filters High-efficiency purified air (HEPA) filters were developed for use with gases where the gas was continually treated with the filter through recirculation. Filters of this classification are very high-volume filters and have been developed to the point that they can be subjected to quite high temperatures (300°F or more) to be initially sterilized. However, the theory behind the use of a HEPA filter is to keep moving the same gas through the filter several times, so after a period of time it is pure. If the gas contains contaminants, they will be trapped by the filter. After a period of time, the filter basically is producing sterile gas. Because the flow of gas is laminar

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and at a greater pressure than the atmosphere (1 to 2 inches of water), contaminants are not drawn into the field, but rather are excluded because of the pressure barrier. Air or gas that is not recalculated must be fairly pure. Purifying air may be accomplished by prefilters or “roughing” filters. HEPA filters are commonly used with aseptic packaging systems where the area to be protected is quite large. Using a cartridge-type air filter to protect a large area from contamination would be impractical. HEPA filters are usually employed with air where the air will be transferred through the filters for a minimum period of time before the air being emitted from the filters is considered sterile. The filter then is continuously operated with air flowing through it until the operation is stopped, the filter removed for cleaning or replacement, or for another reason. After the filter has been replaced or cleaned, operating this system for a period of time until it can be assured that sterile air is being emitted from the filter will be necessary.

4.5.4  General information on filtration Generally, with gas filtration, removal of particles is by initial impaction, diffusion, and interception. In liquids, diffusion and initial impaction are unimportant and only interception is involved. There are other factors involved in gas filtration, including the filtered particles acting as filtering media themselves. Because the technology of filtration is not reviewed in detail, the reader should understand that gas filtration and the filters used are considerably different from liquid filtration that may employ depth filters and that statements made concerning liquid filters are not necessarily applicable to gas filters or vice versa. The statements made by certain manufacturers concerning the ability of their filters to withstand various conditions may not apply. The number of manufacturers having experience in large-volume operations such as those existing in the food or related industries is minimal. Most of the experience of filter manufacturers has been in areas other than food or dairy and may not be applicable to needs in these areas.

4.6 Chemicals used as sterilizing agents (equipment) Chemicals are used in aseptic processing and packaging systems to control the numbers and types of bacteria that are present on equipment. They may be used to kill bacterial forms (vegetative cells, spores, yeasts, and molds) to render equipment commercially sterile or to maintain the sterility desired for processing and packaging systems/machines, aseptic tanks, or other critical components.

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The review of chemicals that are added does not include those that are part of the formula in prepared foods or the chemicals added to certain products to guarantee they have a pH less than 4.6 and can be processed, packaged, and sold to the consumer as an acidified product.

4.6.1  Chlorine and iodine Chlorine is added to most municipal water supplies in the United States to inactivate bacteria that are harmful to humans and to keep the numbers that are present at a very low level. Chlorine added to water in municipal systems is usually at a concentration where the maximum residual chlorine content is 1 ppm. This presumes that the water that contains the chlorine will travel throughout the distribution system of the municipality, which may be many miles and include dead ends. Therefore, the starting concentration may be twice, or more, than the use concentration, or in the 2- to 3-ppm range. Chlorine is very effective and probably kills bacteria through oxidation of critical elements. It is most effective against vegetative cells, which are easily inactivated by this method. Resistant organisms (some vegetative cells and many spores), although the water is chlorinated, may survive and be present. Most yeasts and molds are more sensitive to chlorine than vegetative cells or spores. In aseptic processing systems, chlorinated water is often used after cleaning as a sanitizing agent. It may be left in the equipment overnight so organisms that are not contacted, such as those behind gaskets but later move into the mainstream of the processing system, are inactivated. If chlorine is used, even at low concentrations, and the equipment is heated for sterilization, it can cause stainless steel to corrode. This is much more prevalent if 304 stainless steel is used as opposed to 316 or 316L stainless steel. Because the price differential between 304, 316, and 316L stainless steel is quite small, 316 should be used for all aseptic processing and packaging equipment. The difference between chlorine and iodine, from a practical standpoint, relates to the effectiveness and the strengths that must be used to get equal kill levels. Usually, iodine is much more effective than chlorine and when used as a sanitizer the concentration can be 10% to 25% as great. The kill levels at somewhere between 12 and 25 ppm of iodine may be equivalent to what is possible with chlorine at 100 to 200 ppm. The actual difference will depend upon many factors, including pH and solids that are present. Iodine is not desirable because it leaves a color (yellow to orange, depending upon concentration). However, it is desirable because it is less corrosive than chlorine at concentrations that will yield equal kills. Part of this is due to the fact that iodine may be used at roughly 10% to 25%

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the strength of chlorine. Both chlorine and iodine are very dependent upon pH. Because chlorine is more stable at high pH, it is often sold and made available as sodium hypochlorite. This is a common form available industrially and sold to the consumer primarily for bleaching purposes. Conversely, iodine is much more stable than chlorine in the acidic form. Therefore, it is often sold as a sanitizer in an acid base. Partly because of its acidity, it is much more effective as a bactericide.

4.6.2  Oxonia Oxonia is available from many chemical companies and is a combination of peroxyacetic acid and hydrogen peroxide. It is because it is not corrosive to metal and does not discolor it. This is at the most effective use pH, which is on the acidic side. Normal pH values will be somewhere between 3 and 4. As with chlorine, iodine, and other halogens, it is very reactive with organic material and should be handled and used accordingly. Oxonia is a very effective bactericidal agent and is used primarily for sterilizing difficult-to-contact pieces of aseptic processing or packaging equipment by fogging or spraying. Because of its noncorrosiveness to stainless steels and its excellent bactericidal action, it has been used as a sterilant for food-containing packages and aseptic packaging equipment. It is approved by the FDA for sanitizing equipment and reasonable residuals are not harmful to humans when it comes in contact with food products.

4.6.3  Food acids Food acids have been used for several purposes in aseptic processing and packaging systems. Packages have been sterilized and subsequently filled with acid-type fruit juices or other similar products (acidic) where hot citric acid has been used as the sterilizing agent. The hot food acid inactivates vegetative cells, spores, yeasts, and molds that would grow in the acid product at room temperatures. By using a hot food acid, a natural food component is used during the package sterilization process so there is no regulatory restriction. This concept was used by at least one aseptic packaging system. Another use of food acids has been to maintain the sterility of processing systems used for commercially sterilizing acid products when the system is idling. By maintaining sterility in this manner, the system will not lose sterility if it is operated on idle while packaging operations are delayed. Sterilization varies with time, temperature, and pH of an acidified product-processing system. Acids must be used if the temperatures of sterilization are to be the same, otherwise loss of sterility of the processing equipment or system may occur.

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Usually, the pH of the water used during idling is the same as the pH of the product that is being processed. For example, if a juice being processed has a pH of 4.0, the pH of the water used during idling should be no more than 4.0.

4.6.4  Ozone Ozone is a strong oxidizing agent that is normally in a gas form and has been used primarily in the past for preventing the increase of microbiological deterioration of raw products. Ozone is a very effective sterilant working in much the same manner as halogen compounds that inactivate bacteria; however, it is very unstable in water or liquid solutions. Usually, it must be prepared continuously and applied or put in the media regularly. One way of producing ozone is to pass gaseous oxygen through a high-voltage electrical field that converts the oxygen to ozone. Because ozone cannot be purchased or supplied in liquid form, such as chlorine or other halogens, it is not as convenient and consequently has not been used to the same extent.

4.6.5  Hydrogen peroxide Hydrogen peroxide is used for sterilizing packaging equipment and the packaging material, usually at a 35% concentration. The efficiency of hydrogen peroxide as a sterilizing agent increases with temperature and concentration. It is much more effective if the hydrogen peroxide is converted to oxygen and water vapor through the application of heat to drive the reaction. Frequently, when a solution of hydrogen peroxide is used as a sterilizing agent, heat is applied after application to cause the hydrogen peroxide to break down into water vapor and nascent oxygen, which is the main sterilizing agent.

4.6.6  Ultraviolet Ultraviolet (UV) is not in the truest sense a chemical; rather, it is a wave band that consists of three general regions. The three regions are the vacuum region of 1000 to 1900 Å, which are wave bands absorbed by water and air; the far region of 1900 to 3000 Å, absorbed by biological molecules; and the near region of 3000 to 3800 Å, where the waves are absorbed only by a few molecules. Most germicidal lamps (2537 Å) are used to inactivate bacteria on flat packaging materials, or to a lesser degree, they are used to inactivate bacteria or other biological forms that are in water. As with any form of radiation, the strength decreases as the distance away from the object to which it is being directed increases. The sterilization action is achieved by breaking certain key chemical bonds that are in

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DNA molecules of bacteria. Once these critical molecules are disrupted by cleaving certain chemical chains, the microorganism dies. UV has been used to inactivate certain microorganisms on packaging material. One problem is that if the UV is strong enough to inactive all of the critical microorganisms, the packaging material may be affected. This effect may be in terms of the ability to heat seal; the packaging material may discolor or become brittle, it may react with the food product being packed, or it may lose the ability to restrict the movement of critical chemicals that may cause the food product to deteriorate, such as oxygen and air. It should also be considered that a lamp that produces UV light of a certain wavelength will be at maximum power when it is new. This power will decrease gradually as the lamp is used. After somewhere around 2000 to 2500 hours of operation, the lamp strength will be one half of what it originally was. When the lamp reaches this strength level it is often at, or below, the strength level required to inactivate organisms that may be on the packaging material, with a reasonable safety factor. One reason UV light is not used extensively for inactivating microorganisms on equipment or packages is it can be shadowed and rendered ineffective in the shadowed area. For example, if a material contains dirt or is creased, the area protected will not be exposed to the UV light and microorganisms in this area will not be inactivated. This is one reason it has been used primarily with flat sheets, because normal configurations do not provide shadowing protection. However, the flat sheet must be absolutely clean, which suggests it must first be washed. UV light with very dilute hydrogen peroxide has been reported to be effective as a sterilant.

References 3A Accepted Practices for a Method of Producing Steam of Culinary Quality, no. 609–00. 1996. Formulated by International Association of Milk, Food, and Environmental Sanitarians, United States Public Health Service, and the Dairy Industry Committee. Homer, C., More Changes. Dairy Field Magazine, September 1992, p. 90. Janoschek, R., and Du Moulin, G. 1994. Ultraviolet Disinfection in Biotechnology: Myth vs. Practice. Biopharm Magazine, January–February 1994, pp. 24–31. LeBlanc, D.A., Danforth, D.D., and Smith, J.M. 1993, October. Cleaning Technology for Pharmaceutical Manufacturing. Pharmaceutical Technology Magazine. Tichener-Hooker, N.J., Sinclair, P.A., Hoare, M., Vranch, S.P., Cottam, A., and Turner, M.K. The Specifications of Static Seals for Contained Operations: An Engineering Appraisal. Pharmaceutical Technology Magazine, October 1993, pp. 60–66. Zander Filter Brochures. 1: Ecodry, The Range of Dryers with Performance; 2: Sterile Filters, Aeration Filters and Steam Infusers.

chapter 5

Aseptic filling and packaging equipment Thomas Szemplenski

5.1  Development of aseptic packaging Many people believe that aseptic processing and packaging was invented in the early 1980s when Tetra Pak introduced the first Brik-type paperboard packaging into the United States. In reality, the first patent (no. 2,029,303) for aseptic packaging was granted to C. Olin Ball on February 4, 1936, for aseptic filling into metal cans. The development of aseptic technology grew out of a desire to preserve the beverage quality of milk. The ability to preserve milk before had required the complete alteration of product that came from the cow, goat, or sheep either by drying, condensing, or coagulating. All these alterations maintained the nutritional qualities of milk as a food, but it no longer was the refreshing beverage it was originally. In the early 1960s, the Swedish company Tetra Pak brought its laminated paper-aluminum foil-plastic container to the United States. The system was at that time a continuous form–fill–seal system for fluid pasteurized milk and beverages. The container was a tetrahedron. This package was extremely efficient in material use, but complicated to pack or stack, and a real challenge to open. The U.S. licensee of this system was the Milliken Company in South Carolina, and in conjunction with Real Fresh of California, the Tetra system was modified to include a chlorine sterilizing bath of the packaging web. This allowed sterilized milk to be filled and sealed aseptically, in a hermetically sealed container (R. Graves, personal communication, 2010). Sterilized milk in the tetrahedron achieved a remarkable degree of use within the U.S. armed forces, even though in more than one product demonstration to senior military personnel, milk squirted out of the container onto their dress uniforms. On board submarines the container reduced weight and the ease of disposal made it a hit. On surface ships the tetrahedron was almost impossible to tip over, which was a big advantage 77

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in stormy weather. The container made little inroad into the civilian market, however, mainly due to the difficulty of opening it. As has been previously discussed, the development of aseptic fluid milk was the confluence of the technology of a system to treat the milk and bring it together with a previously sterilized container. The result was milk treated by the Graves–Stambaugh system filled into a metal can processed by the Dole canning system. There was no significant activity in the commercialization of aseptic processing and packaging since the patent was issued until the late 1960s and early 1970s when several food processors with foresight started aseptically processing and packaging shelf-stable puddings using the Dole canning system. In the early 1970s William Scholle invented aseptic bagin-box packaging. The first products to be aseptically packaged into bagin-box were tomato products such as ketchup and tomato paste. In 1981, Tetra Pak returned to the United States with a new and improved packaging using hydrogen peroxide as a sterilant. The basic principle of the system remained the same with a web of laminated material being formed, filled, and sealed in a continuous motion. The new package, unlike the triangle-shaped tetrahedron, was formed and folded into a rectangle or brick. This presented the consumer with a container that looked familiar and suitable and could be displayed on store shelves. The real functional feature was the straw for the smaller containers that was designed to puncture an opening at a specially scored spot. This made the container popular with legions of consumers who liked the portability and ease of consuming whatever the container contained. Aseptic milk and flavored milks experienced their first real introduction to the mass market in the Tetra Brik rectangular-type container. The manufacturers of aseptic milk were hampered by the confusion of finding a suitable and usable term with which the product would be known. Over time, the acceptance of the container for juice products temporarily shelved the need for a new name for true aseptic products. Although aseptic packaging was invented in the 1930s, the real growth was not experienced until the late 1970s and early 1980s. What started out with Dole canning system has exploded into a myriad of aseptic packaging systems that include not only cans, bag-in-box, and Tetra Pak form–fill–seal systems, but also glass, plastic cups and bottles, pouches, coffee creamers, bulk stainless steel containers, aseptic storage tank farms capable of holding nearly 2 million gallons of product each, and even large aseptic ships capable of aseptically transporting 3.2  million gallons of citrus products. There are now more than 30 manufacturers of aseptic filling systems installed in the United States alone with over 600 aseptic installations operating. There are far more aseptic processing and packaging installations internationally where

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refrigeration is at a premium or does not exist. The food and beverage industry has embraced aseptic packaging. It is surely one of the most dynamic areas of the food processing industry, and more aseptic packaging alternatives are sure to be developed in the coming years.

5.2  Dole aseptic canning system As previously mentioned, aseptic packaging was invented using the Dole canner. The Dole aseptic canning system has been utilized in commercial applications since the 1960s. Since its introduction, over 60 systems have been placed into production throughout the world aseptically packaging mainly low-acid foods, such as dairy products, puddings, sauces, soups, eggnog, banana puree, sandwich spreads, tomato paste, applesauce, nutritional beverages, and cheese sauces. Approximately 40 Dole canners are still operating. The Dole system is currently owned and operated by the Graham Corporation. The Dole system fills aseptically processed food products into metal cans at speeds up to 450 cans per minute. Dole is the only system available to fill aseptically processed products into metal cans. Metal cans with seam-on ends are used in all Dole systems. Can sizes range from 4.5 ounces (202 × 214) up to the #10 can (603 × 700). The smaller cans are gen­erally aluminum. The larger cans are two- or three-piece steel. The cans are manufactured with heat-resistance coatings common to the can industry. The lids are made with a high-temperature plastisol sealant, which is standard in the industry. The Dole system consists of four basic components: the can sterilizer, the filling section, the lid sterilizer, and the sealing machine. The components are linked together with an integrated network of instruments, controls, and alarms (Figure 5.1).

5.2.1  Can sterilizing unit The can sterilizing unit is a stainless steel, double insulated tunnel. Superheated steam at a temperature of approximately 500°F (260°C) is introduced into the tunnel sections to provide the heat required for sterilization. The steam is superheated by electric heaters supplied with the system. The cans are moved through the tunnels and the speed of the conveyors is varied to establish the overall capacity of the system. The cans are conveyed in the sterilized unit for approximately 45 seconds until the surface of the container reaches 435°F (224°C), which is the temperature required for the destruction of heat-resistant bacteria. The superheated steam is more lethal than dry hot air and requires less time to destroy the bacteria.

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Can Sterilizer Empty Can In

Can Diverter

Filler Cover Feed

Filled Can Exit Can and Cover Make-Up Station

Cover Sterilizer Seamer

Figure 5.1  A Dole aseptic canner.

5.2.2  The filling section As the hot, sterile containers move into the filling sections, jets of cold, sterile water are directed against the lower portions of the can exterior substantially reducing the container temperature. At this point, the aseptic product is introduced into the container by one of several specially designed filling mechanisms. The Dole system is equipped with specially designed fillers. The basic model is the slit filler. With the slit filler, the cans pass underneath a slit opening in a tube-type filler. The slit is approximately ¼ inch wide by 6 inches long, although the size is variable depending upon the type of product and speed of filling. The slit filler consists of a thick walled, stainless steel pipe that is slit along the lower side. This pipe has a second inner pipe that has multiple parts and provides consistent flow to the filling system. The annulus between the pipes is approximately ½ inch. The sterile product is fed into the inner pipe and flows lows out to the slit in the outside pipe.

5.2.3  Lid sterilizer The third basic component of the Dole aseptic canning system is the cover sterilizing unit. It is arranged as part of the closing machine. Covers or lids are fed in stacks into the unit through one of several

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mechanical devices and are completely enveloped in superheated steam for approximately 80 seconds. At the discharge, the lids are sterile and are conveyed into the closing machine. Either aluminum or steel lids can be used with the Dole canner. Aluminum lids require about 20% less time to be sterilized. Easy-open lids can also be used in the unit.

5.2.4  The sealer The fourth component of the Dole system is the sealing machine. This equipment is often standard machinery that is modified to operate in an aseptic canning system. To accommodate the sterile container filled with cold sterile product and the seaming of the presterilized containers, the closing machine is enclosed and heated with superheated steam. The enclosure permits initial sterilization of the equipment and maintains a completely sterile atmosphere in the area where the sterile container, lid, and product come together. The continuous flow of superheated steam creates a positive pressure inside the can seamer, preventing external, bacteria-laden air from entering.

5.3  Aseptic bag-in-box In the late 1950s William Scholle invented, developed, and patented a more efficient means of containing battery electrolyte using flexible packaging constructed of polyethylene (PE). In time, Scholle visualized potential uses for flexible packaging in the commercial food processing industry. In the late 1960s and early 1970s two things caught Bill Scholle’s attention; first, aseptic processing, a relatively new food processing technology was gaining acceptance by processors; and second, bulk packaging of commercial products such as tomato paste and fruits was costly. At that time, most tomato paste was either hot filled into #10 cans or aseptically filled into expensive 55-gallon steel drums in California and shipped great distances to be reprocessed into other products such as, ketchup, soups, and sauces. Additionally, most fruit products were being filled into 30-pound plastic pails and frozen to be shipped to other parts of the country for reprocessing into flavored yogurts, ice cream, and fruit pies. The plastic pails and cost of freezing was also a very expensive means of packaging and transporting food products to be reprocessed. Scholle Corporation, already one of the largest manufacturers of flexible packaging material, visualized expanding demand for his packaging business by developing a means of aseptically filling acid products such as tomatoes and fruit into less expensive flexible packaging. To this end, Scholle engineered and manufactured a prototype of an aseptic filler for preformed bags into which these products could be filled. The prototype

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filler was installed and improved upon at Purdue University in West Lafayette, Indiana, with the assistance of Dr. Phil Nelson and graduate students. At the time, Purdue University already was improving upon aseptic processing techniques in the food processing facility on campus. With an aseptic processing system already in place, Purdue was a logical place to prove Scholle’s aseptic filler for flexible packaging. Even today, the filling equipment is presterilized with steam, hot water, and chlorine, and the preformed packaging is presterilized with gamma radiation. The sterile zone and product contact parts of the aseptic fillers are subjected to high temperatures (approximately 250°F) for 30 minutes to presterilize the filler prior to production. The bags are manufactured of various polymers with a fitment and cap. After manufacturing, the bags of varying sizes from 1 gallon up to 330 gallons are subjected to the sterilizing gamma radiation before being sent to the end use for filling. With the original Scholle aseptic filler, and even with several models today, the presterilized bags are manually inserted into the filling chambers. Once the fitment and cap are inserted into the sterile filling chamber it is automatically resterilized with steam. The cap is then automatically removed, the filling valve is inserted into the bag, and a vacuum pulled. The sterile product is volumetrically filled into the bags by a flowmeter. After filling, there is a nitrogen flush, then the cap is replaced, and the bag is ejected from the sterile filling zone (Figure 5.2). Over the years there have been many improvements to the original Scholle design, including but not limited to the ability to fill larger bags, the introduction of an automatic continuous web fed bag filler, and validation by the U.S. Food and Drug Administration (FDA) to aseptically fill and package low acid (>pH 4.6) food products. It should be noted that the Scholle filler is capable of filling food products with particulates, such as diced and sliced fruit as depicted in Figure 5.3. While conducting many tests in aseptic processing facilities several processors wanted to push the limit with regard to aseptically processing and packaging low-acid foods with larger and larger particulates. One such international processor wanted to try aseptic processing and packaging ravioli and spaghetti. The products were aseptically processed at approximately 280°F, held for a period of time, and then cooled to a filling temperature of approximately 90°F prior to filling through the fitment on the Scholle bags. Photographs of these products are shown in Figure 5.4. Note the remarkable particulate identity. The international processor who requested this test shipped the product back to his plant in Europe under refrigeration, but later incubated the product because of an indication of bacteria growth. He reported that after one year the product was still commercially sterile. It should be noted, that although the FDA has validated the Scholle and other aseptic bag-in-box fillers for filling low-acid foods, they have

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AUTO-FILL 10-2E SERIES Aseptic Filling System for High Acid Foods

Figure 5.2  One of many Scholle aseptic bag-in-box fillers. (Photograph from a Scholle brochure.)

approved only a few aseptic processing systems containing low acid particulates. Those systems that are FDA approved to fill particulates are filling particulates that are relatively small. As the technology to aseptically process low-acid foods containing larger particulates evolves and the ability to prove sterility improves, it is nice to know that the filling technology has already been proven. William Scholle’s vision regarding market potential was right on, as Scholle Corporation and others manufacturers have installed hundreds of aseptic bag-in-box fillers all over the world. For many years Scholle had almost a monopolistic advantage to the aseptic bag-in-box market, but over the years a number of manufacturers have introduced alternative aseptic bag-in-box fillers. Scholle is still the market leader in the supply of aseptic fillers and most assuredly the supply of aseptic bags and

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Figure 5.3  Aseptic product in aseptic bags. The outer packaging layer has been removed to show the particulate identity.

packaging materials. Some of the other suppliers of aseptic bag-in-box fillers include but are not limited to: Company Astepo Elpo Liqui-Box Fenco HRS JBT FoodTech Rapak Rossi Catelli

Where Manufactured Italy Italy United States Italy Argentina and Spain United States United States and United Kingdom Italy

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Figure 5.4  Aseptic product in aseptic bags.

All the aforementioned fillers utilize basically the same technology for presterilization of the fillers with steam. Some use a combination of steam and chlorine. All preformed bags are sealed and presterilized with gamma radiation.

5.4  Aseptic paperboard fillers 5.4.1  Tetra Pak By no narrow margin the most aseptic packaging equipment for food and beverages is for filling into paperboard carton laminates. In the early 1960s, Tetra Pak, headquartered in Lund, Sweden, reengineered its form– fill–seal tetrahedral packaging filler to be able to fill milk aseptically.

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Figure 5.5  The principle of Tetra Pak asceptic packaging. (Photograph courtesy of Tetra Pak.)

Within several years, Tetra Pak introduced the first Tetra Brik carton, a rectangular-type package of varying sizes and shapes. In the ensuing years Tetra Pak has introduced a myriad of aseptic packaging alternatives each formed by forming packages from roll-fed material, as depicted in Figure 5.5. Prior to filling and forming, the packaging material goes through a bath of 35% hydrogen peroxide at approximately 130°F. This is followed by hot air drying in the sterile zone of the filler, thereby ensuring a sterile package for the independently sterilized product. The paperboard laminate consists of a number of different layers of material based mainly on the product to be packaged. The different layers generally consist of paper, aluminum foil, and several polyethylene layers, as shown in Figure 5.6 obtained from Tetra Pak general literature.

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The layers of the Tetra Brik aseptic package, from the outer layer inward

Polyethylene Printed design

Paper

Polyethylene Aluminum foil Polyethylene Polyethylene

Figure 5.6  One diagram sample of Tetra Pak packaging construction.

As previously mentioned, Tetra Pak has developed many different types of aseptic packaging for food and beverages, including but not limited to the Tetra Brik-type package, Tetra Prisma, Tetra Gemina, and Tetra Fino. On a worldwide basis, no other supplier of aseptic filling equipment or aseptic packaging material even comes close to Tetra Pak’s dominance in aseptic filling and packaging. According to published reports from Tetra Pak in 2008, more than 140 billion aseptic packages were filled throughout 150 different countries. Additionally, Tetra Pak installed almost 600 new aseptic fillers in 2007, bringing their world installations to nearly 10,000. Tetra Pak can fill package sizes from 80 mL up to 2000 mL in many different sizes and shapes at varying fill rates. The list of products being aseptically filled on Tetra Pak fillers is endless. The fillers that were originally developed for aseptically filling milk are now filling fruit and vegetable juices, teas, soups, syrups, sauces, broths, and nutritional beverages, to name a few. With the acquisition of Alfa Laval, a major worldwide supplier of aseptic processing equipment and systems, Tetra Pak can now supply not only the aseptic filling/packaging equipment but also the mutually dependent aseptic processing system. This is a major competitive advantage in the marketplace. Another powerful marketing tool that Tetra Pak has is an FDA-approved aseptic processing testing facility located in Texas where processors interested in aseptic processing and packaging techniques can go to test and generate finished products prior to making a decision to purchase.

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5.4.2  SIG Combibloc SIG Combibloc (hereafter Combibloc) is the second largest manufacturer of aseptic filling equipment and supplier of packaging for beverages into composite cardboard, polyethylene, and aluminum packaging. Combibloc’s home office is in Germany with sales and services in the United States and other countries. Combibloc has many variations of aseptic filling equipment that can fill package sizes from 125 mL up to 2000 mL at varying flow rates up to 24000 pph. Unlike Tetra Pak’s form–fill–seal technique for forming packages, Combibloc’s packaging is preformed into individual packages that are then shipped to the end user as a flat carton that is opened, shaped, and sterilized inside the filling machine. The interior of the carton is sterilized by hydrogen peroxide in the sterile zone, which has a slight overpressure. After sterilization the carton is heated with hot air to dry the hydrogen peroxide. Filling takes place after package sterilization and drying of the hydrogen peroxide. After filling, the carton is ultrasonically sealed above the fill level, not through the product like most Tetra Pak fillers. Filling above the fill level and not through the product facilitates the aseptic filling of food products containing particulates.

5.5  Aseptic plastic cups 5.5.1  Bosch and Erca In the 1970s two new aseptic fillers were introduced to the United States market: the German manufactured Bosch and the French manufactured Erca/Conoffast (now OYSTAR Erca). Both fillers are aseptic linear fillers for form–fill–seal cups. These fillers gained market acceptance as a less expensive alternative to the metal can. The products currently being aseptically canned with the Dole system could now be filled into plastic cups. Puddings, cheese sauces, tomato sauces, and flavored gels are all being aseptically filled using Bosch (Figure 5.7) and Conoffast fillers. Although the Bosch could fill cups at much higher production rates than the Conoffast filler, it was considerably more expensive to purchase. Both aseptic fillers enjoyed market acceptance and success, and both are still being used to aseptically fill food products. Both linear fillers used form­–fill–seal to produce the cups. The Bosch filler used various polymers including polypropylene (PP) to form the cups and the Conoffast used a combination of polystyrene, polypropylene, and polyethylene terepthalate (PET) with a barrier of ethylene vinyl alcohol (EVOH). However, the technology to sterilize the cups was vastly different. The Bosch filler sterilizes the roll-fed packaging material with hydrogen peroxide, whereas the OYSTAR Erca uses either hydrogen

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Figure 5.7  Some product aseptically filled on the Bosch cup filler. (Photograph from Bosch literature.)

peroxide or the neutral aseptic system (NAS). The NAS system sterilizes the material during the coextrusion process. In operation the material is separated and the inner sterile layers form the cups and lid.

5.5.2  OYSTAR Hassia, Erca, Gasti, and Hamba In the 1980s, Hassia, a German manufacturer of form–fill–seal fillers for plastic cups, engineered and introduced to the United States market a high-speed aseptic filler for cups at a very attractive price. Hassia continued to improve upon the production speed of their cup fillers and now can aseptically fill nearly 1700 cups per minute. Unlike most other aseptic fillers that use hydrogen peroxide to sterilize the packaging, Hassia sterilizes the packaging with steam. With its high-speed fillers and aggressive marketing, Hassia has become the leading supplier of aseptic plastic cup fillers in the United States. Puddings, sauces, baby food, and gels are all being aseptically filled using Hassia fillers. Hassia has recently become a member of the OYSTAR organization. The OYSTAR organization also owns other aseptic filler manufacturers including but not limited to Erca, Gasti, and Hamba. All the aseptic fillers are supported by a substantial sales and service organization and spare parts inventory that is based in New Jersey. It should be noted that the only two OYSTAR fillers that are FDA-validated for aseptically filling low-acid foods in the United States are the Hassia (Figure 5.8) and Erca models. The Gasti and Hamba models are being used to aseptically fill acid food products or for filling refrigerated, extended shelf-life products (C. Ravalli, personal communication, 2010).

5.5.3  Ampack Ammann, Benco, and Metal Box Ampack Ammann is a German manufacturer of aseptic filling equipment for preformed plastic cups and bottles of various polymers.

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Figure 5.8  OYSTAR Hassia form–fill–seal aseptic cup filler. (Photograph courtesy of OYSTAR Hassia.)

Ampack is the only company that offers both linear (Figure  5.9) and rotary cup fillers that can fill up to 65,000 cph. Both fillers presterilize the filler with steam and utilize hydrogen peroxide as the sterilizing media for their packaging. Ampack Ammann has been manufacturing aseptic filling equipment since 1978 and has more than 130 aseptic filler installations; however,

Figure 5.9  Ampack Ammann linear aseptic cup filler. (Photograph courtesy of Ampack Ammann and Evergreen Packaging.)

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Ampack does not have any installations in the United States. In the United States Ampack Ammann is represented by Evergreen Packaging located in Cedar Rapids, Iowa. Internationally, Ampack aseptic cup fillers are filling puddings and other desserts, dairy products, fruit conserve with fruit pieces, and layered yogurt. Ampack is the only aseptic cup filler that can aseptically fill two compartment cups. Benco is an Italian manufacturer of aseptic filling equipment for form–fill–seal plastic cups. The Benco filler utilizes steam and hydrogen peroxide to presterilize the filler and hydrogen peroxide to sterilize the packaging. Compared to other aseptic cup fillers the production rate of the Benco filler is slower. At the only installation in the United States, the Benco was being used to aseptically fill puddings, cheese sauces, and fruit-based gels at 220 cpm. At that installation, the Benco was FDA validated to aseptically fill low-acid foods. The plant using the Benco went out of business in the late 1990s. In the 1980s, Metal Box, a manufacturer located in the United Kingdom, introduced an aseptic cup filler utilizing preformed cups. Although relatively slow at 160 cups per minute, Metal Box was able to install several at commercial installations, aseptically packaging puddings, desserts, oatmeal, and cheese sauces. Most of those installations have opted for higher production-rate fillers. At the present, there is only one Metal Box aseptic cup filler at a commercial installation in the United States. It is currently at a copacking facility in Minnesota where it is mainly packaging cheese sauces. The Metal Box aseptic filler was purchased by FMC FoodTech, which has recently changed the name to JBT FoodTech. However, JBT FoodTech does not appear to be aggressively promoting the Metal Box filler any longer.

5.6  Coffee creamers In the United States there are 3 suppliers of aseptic filling equipment for coffee creamers with more than 20 installed and operating. The three suppliers of aseptic filling equipment for coffee creamers are Purity, OYSTAR Hassia, and Bosch. Bosch is the dominant supplier with 13 aseptic coffee creamer fillers installed. Some of these coffee creamer fillers can aseptically fill up to 1400 creamers per minute using Bosch’s Model TFA 4940 filler (Figure 5.10).

5.7  Aseptic pouches All aseptic pouch fillers use form–fill–seal for forming the pouches. Additionally, all aseptic pouch material of various polymers are sterilized by warm, 35% hydrogen peroxide, and followed by hot air drying.

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Handbook of aseptic processing and packaging Aseptically operating thermoform fill and seal machine TFA 4940 for safe packaging of coffee cream

Figure 5.10  An aseptic coffee creamer filler. (Photograph from a Bosch brochure.)

5.7.1  Bosch In the 1970s, Robert Bosch GmbH, a German manufacturer of food packaging equipment, engineered, manufactured, and installed the first aseptic filler for filling food products into form–­fill–seal pouches. The first products to be filled were puddings and cheese sauces that were previously filled into #10 cans. Other manufacturers of aseptic filling equipment saw the potential for food products to be aseptically packaged into flexible packaging and several introduced alternative aseptic fillers for flexible pouches. At the present, there are five suppliers of aseptic filling equipment for pouches at about 20 aseptic pouch installations in the United States alone filling products such as puddings, cheese sauces, chili, dairy products, juices, ice cream mix, and tomato products such as ketchup and paste. Customers and end users found that not only were flexible pouches much less expensive, but they were easier to open, easier to dispose of, and less expensive to ship. The flexible pouches are constructed of low-, medium-, or high-barrier materials from multiple layers of polyethylene, linear lowdensity polyethylene, and EVOH. Some of the pouches are metallized as an extra barrier. Pouches generally range in size from 200 mL up to 10 L.

5.7.2  DuPont/Liqui-Box and Inpaco Inpaco, a manufacturer of pouch fillers located in Nazareth, Pennsylvania, followed Bosch with the introduction of an aseptic pouch filler and was

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quick to grab a share of the market and installed six aseptic pouch fillers in the United States. In the ensuing years, Inpaco sold this business to LiquiBox in Worthington, Ohio. Liqui-Box was a likely buyer as it had already established itself as one of the leading suppliers of flexible packaging and additionally had aseptic filling equipment for bag-in-box. DuPont Canada had previously purchased Liqui-Box Corporation. With the Liqui-Box purchase, DuPont already had an established aseptic pouch filler and therefore discontinued the Inpaco model, although it still services the Inpaco fillers that are operating and would take an order for an Inpaco filler.

5.7.3  Fres-co One of the most recent aseptic pouch filler introductions in the food industry is manufactured by Fres-co System, a Telford, Pennsylvania, corporation. The Fres-co pouch filler is well engineered and is a fully automatic pouch filler that can aseptically fill high- and low-acid food into pouches. Filling speeds vary with pouch size, product characteristics, and film selection, but generally the Fres-co filler can fill 1-gallon single lane pouches up to 30 pouches per minute and ½-ounce multilane pouches up to 500 pouches per minute. The Fres-co filler can fill into either flat or stand-up pouch configuration. Additionally, the Fres-co filler is the only pouch filler that can fill pouches with fitments (B. Pritchard, personal communication, 2010). Fres-co has placed several aseptic pouch fillers in commercial installations and has received FDA validation for aseptically filling low-acid food and beverages. The Fres-co pouch filler is also capable of filling food products containing particulates. A photograph depicting the Fres-co filler and accompanying aseptic module and aseptic surge tank is shown in Figure  5.11. Note the system is skidded and requires relatively little floor space.

5.7.4  OYSTAR Hassia A relatively new aseptic pouch filler has been introduced by OYSTAR Hassia. The Hassia pouch filler can fill food products into pouches up to 6 inches wide and 10 inches long at a filling rate of 10 pouches per minute. Hassia’s aseptic pouch filler has FDA validation for aseptically filling low-acid food products. Several Hassia pouch fillers are operating in the United States filling puddings and sour cream.

5.7.5  Cryovac Cryovac Food Packaging is a division of Sealed Air Corporation. Cryovac is the leading manufacturer of filling equipment and packaging material for food products into flexible pouches. Cryovac pouch fillers are capable

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FSU-1000 Automatic Form, Fill, and Seal Aseptic Packaging System

Figure 5.11  An aseptic pouch filler. (Photograph courtesy of Fres-co System USA, Inc.)

of filling food products containing particulates exceeding 1 inch with little or no damage to the particulates. Within the last several years Cryovac developed and manufactured a pouch filler capable of aseptically filling high- and low-acid foods. The first aseptic pouch filler is installed in Europe, but with Cryovac’s aggressive marketing it is expected that this filler will be introduced to the United States market in the near future.

5.8  Aseptic plastic bottle fillers There are 11 manufacturers of filling equipment for filling aseptically processed beverages into plastic bottles being marketed in the United States. Some of the aseptic fillers are FDA validated for filling low-acid beverages; others can only fill high-acid beverages and products that are destined for refrigerated, extended shelf life. Beverages that are filled using extended shelf-life fillers usually process the product using aseptic processing techniques and fill the product at a much lower temperature for refrigerated warehousing and distribution. This product must be kept under refrigeration. Extended shelf-life products normally have a refrigerated shelf life of 3 to 4 months depending upon the product being packaged. Most plastic bottles destined for aseptic filling are produced from polypropylene, high-density polyethylene (HDPE), or PET. Prior to filling,

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the bottles are presterilized using either 35% warm, hydrogen peroxide or various concentrations of peracetic acid.

5.8.1  Ampack Ammann The German manufacturer of aseptic bottle filling equipment, Ampack Amman is only one of two manufacturers that offers both linear and rotary bottler fillers. The linear filler is an aseptic filler. Ampack rotary filler for plastic bottles is marketed as a filler for extended shelf-life products. Ampack has many aseptic bottle fillers installed internationally, however, they have yet to place one in the United States in spite of strong representation through Evergreen Packaging. Needless to say, with no installations in the United States, Ampack has not received FDA validation for aseptically filling low-acid beverages.

5.8.2  Bosch The first manufacturer to introduce an aseptic filler for beverages in the United States was the Robert Bosch Company. In the late 1970s or early 1980s Bosch installed two bottle fillers for aseptically filling nutritional beverages (Figure 5.12). Bosch received FDA validation at this installation for aseptically filling low-acid beverages into plastic bottles. The fillers filled products at a relatively slow production rate compared to the fillers being supplied by the latest aseptic bottle fillers being offered today. Since the initial installation, Bosch has not supplied any other aseptic bottle fillers in the United States.

5.8.3  Krones Krones is a German manufacturer of both aseptic equipment for processing and packaging beverages into plastic bottles. Only a few equipment manufacturers offer both the aseptic filling and mutually dependent processing equipment, affording their customers a single source of supply and responsibility. Krones has a major sales and service organization located in Wisconsin. Krones can fill bottles sizes up to 2 liters and have production rates up to 700 bottles per minute. Krones has aseptic filler installations for acid foods and extended shelf-life fillers for low-acid beverages in the United States. At present Krones has not received FDA validation for aseptically filling low-acid beverages.

5.8.4  OYSTAR Hamba Hamba, now a member of the OYSTAR organization, has been manufacturing aseptic filling equipment for many years. Hamba’s initial aseptic

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Bosch Aseptic Filler for Bottles Aseptically operating filling and closing lines for bottles and wide-mouth containers of glass and plastics

2. Bottle sterilizing 2

4. Lidding

3. Filler

4

1 1. Presterilizing unit

5 5. Discharge

Figure 5.12  An aseptic bottle filler. (Diagram from Bosch published literature.)

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equipment was developed for filling food products into preformed cups using a linear filler. Most recently Hamba introduced a linear aseptic bottle filler for plastic bottles. At the time of this publication Hamba was installing this filler in the United States but had not yet applied to the FDA for validation to fill low-acid beverages. The Hamba manufacturing facility has recently been relocated to the OYSTAR Hassia facility in Ranstadt, Germany, and is being marketed in the United States through the OYSTAR facility in New Jersey where management, sales, service, and spare parts are located.

5.8.5  Procomac GEA Procomac S.p.A. is an Italian manufacturer of rotary aseptic filling equipment for beverages into HDPE and PET bottles. Sales, service, and spare parts for Procomac in the United States is located in Hudson, Wisconsin. Procomac also has a testing facility located in Parma, Italy, for potential users to test their product using the equipment prior to purchasing. Procomac first developed an aseptic bottle filler in 1994, and is now one of the world’s leading suppliers of aseptic bottle filling equipment (Figure  5.13). In the United States, Procomac has been very successful and has installed many aseptic bottle fillers for high- and low-acid beverages. Procomac has received FDA validation for filling low-acid

Figure 5.13  Procomac aseptic filler for plastic bottles. (Photograph courtesy of Procomac.)

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beverages. Additionally, Procomac fillers can fill beverages with small particulates. Procomac aseptic bottle fillers can fill bottles sizes from 250 mL up to 2 L. Depending upon bottle size and configuration, Procomac fillers can fill at a production rate of up to 800 bottles per minute.

5.8.6  Serac Serac is one of the world’s leading suppliers of aseptic filling equipment for plastic bottles and the leading supplier of aseptic and extended shelf-life (ESL) fillers in the United States. Most Serac aseptic fillers are manufactured at the home office in France, however, several aseptic and extended shelf-life fillers are manufactured at the Serac sales and service facility located in Carol Stream, Illinois, where Serac also maintains a large spare parts inventory. Depending upon bottle sizes and configuration, Serac bottle fillers can fill up to 800 bottles per minute. Both the high- and low-acid fillers can fill bottle sizes from 75 mL up to 3 L. Bottle material can be constructed of PET, HDPE, PE, or Barex (Figure 5.14).

Figure 5.14  Some beverages being filled on Serac fillers. (Photograph courtesy of Serac USA.)

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Serac has not received FDA validation for aseptically filling low-acid beverages but expects to do so in the near future.

5.8.7  Shibuya Kogyo Shibuya Kogyo is one of the leading suppliers of aseptic fillers for plastic bottles. Shibuya installed its first aseptic bottle filler in 1994 and has since installed over 100 others, filling products such as milk, teas, coffee, and juices. The Shibuya bottle filler has received FDA validation for aseptically filling low-acid beverages. With filling speed up to 1200, the Shibuya bottle filler has the highest production rate of all aseptic bottle fillers. Shibuya has recently developed the first electron beam sterilization method for PET bottles achieving a log 6 reduction. The use of electron beam for sterilization of the bottles eliminates any possibility of chemical residuals and substantially reduces the cost of not only chemical sterilants, but also steam, water, and other utilities. It also substantially reduces required floor space.

5.8.8  Sidel/Tetra Laval Sidel is a division of Tetra Laval and offers two styles of aseptic fillers for plastic bottles: two models of rotary fillers and a linear filler. Sidel has over 100 installed and operating aseptic bottle fillers, filling products such as teas, milk and other dairy products, juices, and flavored water. The fillers will fill into polypropylene, PET, or HDPE bottles. Sidel’s rotary fillers are for aseptic acid products and for refrigerated extended shelf-life products. The Tetra Pak linear fillers (LFA-20) are FDA validated for aseptic filling of low-acid beverages (Figures 5.15 and 5.16). The linear fillers have a much lower production rate than the rotary fillers, which can fill up to 60,000 bph. Sidel offers three methods of sterilization of the plastic bottles: wet decontamination with peracetic acid, wet decontamination with hydrogen peroxide, and a patented (PredisTM) dry decontamination using hydrogen peroxide vapor. Sidel’s rotary fillers use either the wet decontamination with hydrogen peroxide or the Predis method. Sidel’s (Tetra Pak) linear filler utilizes hydrogen peroxide to sterilize the bottles. Sidel’s patented Predis method of sterilizing the bottles is quite unique and reduces the cost and chance of chemical residuals. The method uses preforms. Hydrogen peroxide is deposited onto the internal wall of each preform as condensation (120°C to 140°C). The preforms are then heated in the oven until they reach a temperature of up to 100°C, which activates the H2O2 in a controlled atmosphere. The bottles are then blown using 0.01 micron filtered air after which they are transferred by the neck into the sterile filler to be filled and capped (Figure 5.17).

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Figure 5.15  Sidel/Tetra Pak LFA-20 linear aseptic bottle filler. (Photograph courtesy of Tetra Pak.)

Figure 5.16  Samples of some aseptic product filled on the LFA-20. (Photograph courtesy of Tetra Pak.)

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Figure 5.17  Sidel’s SensofillTM FMa aseptic bottle filler. (1) The multiwheel bottle sterilization system. (2) High-pressure bottle sterilization. (3) Aseptic filling. (4) Cap sterilization. (Photograph from a Sidel brochure.)

5.9  Stork Stork is a leading and long-time manufacturer of aseptic processing and filling equipment for beverages into plastic bottles, and one of the few manufacturers that offers a linear bottle filler. Products such as fruit juices, milk and other dairy products, soy milk, teas, and coffee drinks are all being aseptically filled with Stork bottle fillers. Additionally, the Stork

Figure 5.18  Stork linear aseptic filler for plastic bottles. (Photograph from a Stork brochure.)

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bottle filler can fill beverages with particulates up to 12 mm in diameter. In the United States, Stork has received FDA validation for aseptically filling low-acid beverages into plastic bottles. The Stork filler can fill bottle sizes from 20 mL up to 2 L at a filling rate of 400 bpm (Figure 5.18). Plastic bottles of PET, HDPE, and PP are being sterilized with hydrogen peroxide and aseptically filled using Stork fillers. Bottles can be monolayer, three layer with light barrier, or up to six layers with both light and oxygen barriers (P. Schweitzer, personal communication, 2010).

chapter 6

Aseptic packaging materials and sterilants Robert Fox

6.1  Product requirements All products have specific package requirements necessary to keep the product in a safe and acceptable condition for its expected shelf life. In order to maintain the integrity of the package, these requirements may include functional barriers to light, oxygen, and moisture as well as mechanical properties such as the container’s distortion temperature, stiffness, and impact properties. Figure 6.1 provides a broad view of the oxygen tolerance of various products found in shelf-stable and refrigerated packages. Low-acid particulate products that are aseptically packed present a U.S. Food and Drug Administration (FDA) challenge in the United States but can be found in the European Union and other countries outside the United States. For that reason they are included in this chart. Some products have a need for a high degree of protection from the effects of ultraviolet (UV) light. A UV inhibitor can be added to minimize product degradation or the container can have an opaque layer. Most products have a need for a high degree of protection from moisture gain or loss. The next section discusses materials that have been identified as capable of providing suitable protection from either the ingress or egress of oxygen or water vapor.

6.2  Materials Thermoplastic materials used in sheet production for both aseptically packed nonbarrier and barrier thermoformed packages have been chosen for properties that they provide.

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Oxygen Sensitivity and Fill/Process Temperatures for Foods and Beverages 250°F 219°F

Baby Food, Seafood, Soups, Meats, Pudding, Pet Food, Canned Milk, Vegetables

RETORT/LOW-ACID ASEPTIC

212°F 205°F 190°F

100°F

Isotonics, Juices

RTD Tea

HOT FILL/PASTEURIZATION/HIGH-ACID ASEPTIC

Pasteurized Beer

BBQ Sauce, Salad Dressing, Syrup, Mustard Warm-Filled Ketchup

WARM FILL Condiments, Liquers, Edible Oil Shortening, Peanut Butter Isotonics

COLD FILL

200

100

50

Figure 6.1  Oxygen tolerance of food groups.

Dried Foods, Nuts, Snacks, Coffee

Cultured Dairy Products

Refrig. RTD Tea

Nonpasteurized Beer/Wine

Refrigerated Cold-Filled Ketchup

40 35 30 25 20 15 Oxygen Sensitivity in Parts per Million (ppm)

10

5

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185°F 176°F

Applesauce, Spaghetti Sauce, Baby Food, Ketchup, Fruits, Salsa/Taco Sauce, Fruit Juice and Drinks

Hot Pack Pickles Jams/Jellies

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6.2.1  Nonbarrier sheeting Nonbarrier sheeting can be made of a single material but usually has two or more layers of different materials to reduce cost. Materials are chosen so that the outer layer(s) provide notch sensitivity resistance, cold temperature impact strength, and improved heat seal capability. The inner core material provides stiffness.

6.2.2  Barrier sheeting No single material can supply all of the properties required to produce a barrier container at an acceptable cost. Different materials are brought together in a layered structure (typically five to seven layers) to provide an adequate level of protection to the product at an acceptable cost. Oxygen barriers of all materials can be significantly improved by the use of nanoclays, active scavengers, and vacuum deposition of metal or glass. Heat distortion can also be improved by the addition of inorganic fillers. In actuality, within a given material, changing any one property by the introduction of an additive influences all the other properties. The following chart lists some of the common materials used in packaging and their respective barrier and physical properties.

Material

Density

Oxygen Barriera

MVTRb

Heat Distortionc (°F)

Flex Modulusd

LLDPE HDPE PP HIPS EVOH PET NYLON 6 PLA

0.91–0.94420 0.95–0.96 0.90–0.91 1.06 1.1–1.2 1.29–1.40 1.12–1.14 1.23–1.25

1.0–1.5 160 150–240 226 .02 90.0 2.6 >150

10.0

40–105 149–176 125–250 165–200 >250 167 311–365 104–150

145–225 170–250 160–390 — 350–450 405 350–450

a b c d

cc/mil/100 sq in2/24 hr at 65% RH/20°C grams/mil/100 in2/24 hr at 90% RH/100°F; MVTR: moisture vapor transmission rate ASTM D-648 at 66 psi ASTM D-790 at 103/73°F

6.3  Sterilizing Agents Heat, chemicals, radiation, and ultraviolet light have been used independently or in combination to sterilize materials for aseptic packaging. Regulatory requirements and cost considerations have put a practical limit on the number of sterilants in commercial use.

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6.3.1  Heat Steam is an effective sterilant demonstrated by the fact that it has been in commercial use longer than any other sterilant. Although steam is not suitable for some thermoplastic materials whose heat distortion temperatures are below the high-pressure steam temperatures required, it has had a recent revival in the OYSTAR Hassia aseptic form–fill–seal packaging system (Figure  6.2). Incoming rolls of plastic sheeting are heated on the top (food contact) surface with culinary steam (320°F) sufficient to sterilize the contact surface. The sheet is then indexed to the forming area where it is heated to its forming temperature and then indexed to the forming station where it is formed into the desired container shape. The next index moves it into the filling area followed by the sealing station and indexed out of the sterile zone. Container sterilization starts with the steam sterilization of the sheet’s surface and continues through the forming, filling, and sealing stations after which containers exit the sterile zone. Lidding material is similarly sterilized prior to entering the sterile zone and sealed to the container.

6.3.2  Hot water Hot water (sometimes acidified) has been used commercially for highacid products. The CrossCheck system, developed and patented by Mead Packaging (U.S. patent 4,152,464), was commercialized by a joint venture of Mead Packaging and Rampart Packaging. CrossCheck was used successfully by Seneca Foods for single-serve applesauce for more than 10 years. Preformed containers were carried through a hot water (180°F) bath, exiting the bath in an inverted position (Figure 6.3). The heat seal flanges and inside of the containers were dried by the flow of warm sterile nitrogen as they rotated to an upright position prior to filling. Sterile nitrogen also maintained a slight positive pressure on the inside of the sterile zone. The sterile zone was presterilized by the use of culinary steam. Cups were filled volumetrically, sealed, and exited through a sterile water lock. Mead and Rampart stopped supporting the technology in 1990.

6.3.3  Neutral aseptic system (NAS) Manufactured by OYSTAR Erca-Formseal, the system uses the heat of the forming and lidding web coextrusion to sterilize the two webs. The bottom web is typically made up of polystyrene–adhesive–EVOH– adhesive–LDPE–PP. The top web is typically made of PP–LDPE– adhesive–aluminum foil. In both structures, the edges of the webs are trimmed as they enter the sterile zone. The polypropylene layer of the bottom web is stripped away and exits the sterile zone. The remaining

Forming oven

Forming station

Roll of plastic sheet

Figure 6.2  OYSTAR Hassia aseptic form–fill–seal system schematic.

Filling area

Sealing station

Aseptically packed cups

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DAMPF Steam header

107

108

Sealing station with sterilant bath Preformed cup loading station

Sterilant bath & water lock exit feature

27

1 Sterilant bath

2 89

14

21

Sterile zone

41 16 18

19 22 23

17

26

3

4

24 25

40 20

8a

5

6 34

13

11

Figure 6.3  Cross Check aseptic deposit, fill, and seal system.

12

50

37 36 15a

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7

Aseptic volumetric filler

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web has the newly exposed sterile surface and is indexed into the heating, forming, and filling stations. The top web, similarily having had its polypropylene layer trimmed and removed as it entered the positive pressure sterile zone, is indexed to the sealing and trimming stations.

6.3.4  Chemical sterilants Hydrogen peroxide (H2O2) is a clear, slightly viscous oxidizing agent that has been the chemical sterilant of choice for most packaging equipment manufacturers. It is an effective sterilant when used in concentrations of 30% to 35% followed by hot air at 60°C to 125°C. The hot air substantially increases sporicidal activity in addition to dissipating the residual hydrogen peroxide. Hydrogen peroxide identified in the Code of Federal Regulations under 21 CFR 178.1005 may be safely used to sterilize polymeric foodcontact surfaces identified in paragraph (e)(1) of the regulation. Hydrogen peroxide also meets the specifications of the Food Chemicals Codex (3rd ed., 1981, pp. 146–147). Peracetic acid (CH3CO3H) is a colorless, liquid organic compound that is highly corrosive. It is always sold in solution with acetic acid and hydrogen peroxide to maintain its stability. The concentration of the acid as the active ingredient can vary depending on its application. It has an advantage over hydrogen peroxide in that it can be used at lower temperatures (40°C). This is a benefit for aseptic packaging applications using materials like polyethylene terepthalate (PET) and LDPE, which have low heat distortion temperatures. It can also be used as an aseptic bottle rinse, spray, or mist without the need for a secondary sterile water rinse. Peracetic acid is accepted by the FDA for sanitizing and disinfecting (21 CFR 178.1005-1010).

6.3.5  Radiation Irradiation has been evaluated for several forms of packaging and found to be an effective solution for large capacity bags such as Scholle’s bagin-box aseptic packaging system. The dominant method of sterilizing hermetically sealed bags, pouches, and drum liners is by electron beam irradiation. Gamma irradiation has been evaluated and is not used for these types of applications due to its initial installation costs and regulatory considerations and potential damage to polymeric packaging materials. Scholle, the leader in bag-in-box aseptic packaging systems, has developed closure features and filling equipment that maintain asepsis during the filling operation. Guidelines for radiation sterilization can be found in 21 CFR Part 178.1005.

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6.4  Packaging systems 6.4.1  Dole aseptic canning The Dole aseptic canning method differs from other aseptic packaging methods in that the packaging materials are subjected to culinary steam as the primary method of container sterilization. Containers are subjected to surface temperatures of 215.6°C to 218.3°C (420°F to 425°F) and cover temperatures of approximately 210°C to 212.8°C (410°F to 415°F). Today, the high temperatures required in their container sterilization restrict the choice of materials to metal two- or three-piece cans. Work is ongoing to develop a CPET container that would withstand the temperature requirements of the process and provide a cost effective replacement with the benefit of microwavability.

6.4.2  Preformed thermoformed containers Aseptic preformed plastic container usage appears to be on the rise in Europe with recent installations of OYSTAR Gasti’s Dogaseptic aseptic packaging system. The system utilizes hydrogen peroxide as the sterilizing agent in the aseptic system. OYSTAR Gasti also has a Dogatherm preform aseptic cup filling system that uses steam to sterilize the inside of the cups and a long-life version that utilizes high intensity UV-C light for sterilizing the container flange and interior surfaces.

6.4.3  Form–fill–seal (FFS) Form–fill–seal includes four main methods of container manufacture:

1. Paper-based packages such as fiberboard cartons and “brick packs.” 2. Thermoformed plastic packages, commonly referred to as cups and trays. 3. Injection and extrusion blow-molded bottles. 4. Bag-in-box and large volume pouches.

The best known of the aseptic FFS packages is the paper-brick-style package that utilizes a multilayered web (Figure 6.4) consisting of an • • • • • •

Outside layer—polyethylene (for protection of fiberboard) Structural layer—paper (typically one side preprinted) Adhesive layer (bonds foil and paper, minimizes fiber penetration) Barrier layer— aluminum foil Adhesive layer Food contact layer— polyethylene

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Polyethylene Paperboard Tie Layer Aluminum Barrier Tie Layer Polyethylene

Figure 6.4  A typical material structure in preformed, paper-based barrier cartons.

Paper-brick and carton-style packages are produced by two different methods. These packages are usually used for dairy-based beverages, juices, stock, and sauces.

1. Roll-fed, paper-based systems (Figure 6.5)—The leading producers of roll-fed, paper-based packaging systems and materials are Tetra Pak, Division of Tetra-Laval, Elopak, subsidiary of the Ferd Group of Norway, and GA Pack, a new Chinese supplier of paper-based packaging j for roll-fed aseptic packaging systems. Efforts to minimize the effects of energy-related cost increases during the 30-plus years that the brick pack has been in commercial use produced a 30% reduction in aluminum foil thickness and a 20% increase in board stiffness while reducing package weight by 15%. Although costs have been positively affected by these changes, other aspects of the carton have been adversely affected. These would include: • Thinner aluminum foil increases the potential for pinholes to develop. • Stiffer board increases the potential for pinholes to develop as a result of stiffer fiber content. • Increased thickness of the adhesive material between the foil, the board, and the PE layer, and the foil and PE layers on the inside of the carton, to minimize/eliminate fiber-induced pinholes through the foil and PE layers increasing the risk of organoleptic impact as a result of chemical migration. 2. Preformed cartons—Preformed brick pack and gable top, fiberboard cartons are used in either high- or low-acid aseptic filling systems. The cartons are manufactured so that the bodies are preassembled and distributed in the flat. They are opened just prior to the filling process with the container body being fin sealed at the bottom. The

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Tetra Brick cartons are filled and sealed below the surface of the liquid.

Figure 6.5  A typical roll-fed process schematic.

tabs that result from the fin seal are folded over the bottom seam or up along the sides of the container body. Materials used to produce the containers are similar in construction to those used to produce the roll-fed, brick-style cartons. Differences are usually found in the thickness of the fiberboard to compensate for increased carton stiffness required for larger container capacities. Pinhole issues and solutions to them are similar to those of the roll-fed laminate. Recently, SIG Combibloc, a unit of the Rand Group, commercialized a nonfoil-based barrier carton. The EcoPlus carton replaced the foil barrier layer with a nylon-6-based barrier polymer. It was introduced in the European Union and is expected to replace its foil-based barrier board materials over the next few years with positive environmental advantages.

Chapter 6:  Aseptic packaging materials and sterilants The Net Results of “cb3 EcoPlus” Are

More

113 Loss

Favorable than those of “cb3” (=100%) Acidification

by 22%

Climate change

by 20% by 12%

Aquatic eutrophication Terrestrial eutrophication

by 7%

Summer smog (POCP)

by 19%

Human Toxicity—PM10

by 20%

Fossil resource consumption

by 22% by 8%

Use of nature—forestry Total primary energy demand

by 15%

Nonrenewable primary energy demand

by 20%

Transport intensity—lorry

by 3%

Left column: “cb3 EcoPlus w/cCap” has lower indicator values (i.e., a more favorable performance) than “cb3 w/cSwift” Right column: “cb3 EcoPlus w/cCap” has higher indicator values (i.e., a less favorable performance) than “cb3 w/cSwift” Note: Percentages shaded in gray are smaller than 10% and thus considered insignificant.

Figure 6.6  An environmental comparison of paper/polymeric versus paper/foil barrier materials used in food packaging.

Combibloc contracted the Institute for Energy and Environmental Research, Heidelberg, Germany, to investigate some of the environmental impacts of the new EcoPlus carton and compare its findings to those of traditional foil-based cartons of similar sizes. Figure 6.6 summarizes the institute’s findings. The comparison of EcoPlus carton and cCap closure was made against Combibloc’s similar standard “cb3” carton with a cSwift closure. The net result of the institute’s study confirmed the polymeric barrier carton has significant energy savings and carbon footprint advantages over the foil-based traditional carton. It appears that foil’s advantage of low tensile strength, useful in opening features that require puncturing the foil and inner polymer contact layer of the carton by straw insertion or leveraged spout opening, may have been met with the polymeric structure. Both the roll fed and preformed aseptic fiberboard packages are typically sterilized by hydrogen peroxide when packages are to be used with low-acid foods. Packages to be used with high-acid foods can include sterilants such as peracetic acid-based sterilants in addition to hydrogen peroxide. Other methods that have been used, to a far lesser degree, include UV-C, gamma, and electron beam radiation. The environmental impact of the paper-based packages has not lived up to its expectation as there is no good reuse of this scrap material (sustainability) other than as a source of energy through incineration or as a component in the production of extruded lumber replacement. In purposeful

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incineration, toxic byproducts are reduced compared to traditional fossil fuel resources found in other packaging materials. Additionally, the bulk of the package is comprised of a renewable resource wood pulp that helps to keep its carbon footprint small. Thermoformed plastic packages are commonly referred to as cups and trays. These packages are typically used for an individual serving of products such as puddings, baby foods, dairy creamers, yogurts, and long-life entrées.



1. Sheet/roll-fed systems—Widely used today for all-plastic containers are being commercially sterilized using the acceptable methods of hydrogen peroxide, peracetic acid, and steam (product/package dependent). 2. Preformed container aseptic systems—Not widely used in the United States, preformed aseptic container systems are commercial in other parts of the world. Sterilization methods include chemical, steam, and ultraviolet light. • Injection and extrusion blow-molded bottles—These packages are typically used for dairy-based beverages and juices. • Preformed injection blow-molded bottles typically utilize preforms in the manufacturing process. While many systems are in commercial operation today, the two primary methods of sterilizing the container prior to filling are: −− Dry preform decontamination method—Sterilants are dep­ osited onto the internal wall of each preform. Preforms are then heated in the forming oven until they reach their forming temperature (greater than 100°C), which activates the H2O2, sterilizing the interior of the container. Containers are then blown into their final shape and transported to the filling and sealing stations in a sterile overpressure environment. −− Wet-sterilization process—This process uses hydrogen peroxide or peracetic acid-based sterilants. Bottles are formed and the sterilant is dispensed into the formed container. An activation temperature of 100°C is required for hydrogen peroxide and 40°C for peracetic acid. The low activation temperature of peracetic acid-based sterilants is well suited to PET as it is well below the thermal distortion temperature of the polymer. • Extrusion blow-molded bottles are typically provided to the aseptic filling system in bottle form. If the bottle is in a closedtop format, its interior is sterile. This is not the case if the bottle is open topped. • Closed-top aseptic filling process—The closed-top process blow molds bottles using sterile air and maintains sterility prior to

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filling by pinching closed the bottle above the container finish at the time the bottle is produced. The combination of the polymers’ temperature during the extrusion and blow-molding process, in combination with the sterile air used to blow the bottle into its desired shape, guarantees a sterile container. The top above the finish is removed in a sterile, controlled environment prior to being aseptically filled. • Open-top aseptic process—Open top blow molded bottles have the top section above the finish removed during the blow molding process. Sterilization of these types of containers is identical to the wet sterilization process identified for injection blow molded containers. Bag-in-box and pouch containers are typically used for bulk packages of foods to reduce storage or shipping costs. Products shipped or stored in this manner are usually transferred aseptically to smaller packaging formats for retail distribution. Large volume (typically ½ to 1 gallon) pouches are also used for retail and institutional sizes and are commonly used to package wine, cheese sauce, and ketchup and tomato sauces, as well as dairy based products. Large volume bag-in-box and pouches are fabricated of coated, metalized, laminated, or co-extruded films. Due to their size and lack of being able to maintain shape independently, they are sterilized using radiation. Radiation sterilization allows bags and large volume pouches to be sterilized in a closed, hermetically sealed condition. Access fitments such as molded openings or valves are attached with their upper and lower openings sealed with a plastic or foil membrane. These fitments are welded to the interior or exterior of the bag or pouch prior to final sterilization. Presterilized bags are stored and shipped to filling sites in a lay-flat condition. At the filling site, the bags are placed in a box or container and the filling fitment is suspended at the top of the box or container to minimize any air entrapment during filling. The container-opening feature is connected to a sterile filling head/valve and the exterior of the opening feature is sterilized prior to the aseptic filling head puncturing the membrane seal across the top of the fitment. Once filled, the opening feature is resealed and a protective overcap applied. Smaller bags and pouches are fabricated and aseptically filled in the same manner as rolled-fed, paper-brick-pack-type packages.

6.5  Environmental considerations Sustainability is a main consideration when looking at packaging options today. Energy conservation is also a main concern as it relates to sustainability and the environment. Figure  6.7 shows the recoverable and

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LDPE

Energy Content Flex, microcellular foam of Various Rigid urethane foam Packaging HDPE Materials Polystyrene PVC ABS Polypropylene Acrylic Recoverable Polycarbonate Feedstrock Polyester Fuel Nylon 66 Nylon 6 Mod PPO Acetal Glass Steel Zinc, die cast Aluminum, die cast Magnesium

1000 2000 3000 4000 5000 6000 7000 8000 9000 10,000

BTU/Cubic Inch of Packaging Material

Figure 6.7  Recoverable energy components of various packaging materials.

nonrecoverable energy component of various materials used in packaging. It becomes easy to see which materials will have the largest carbon footprint and which materials will be the most environmentally friendly. Assuming that all packaging materials will end up in the municipal waste stream at some point in time, it is important to look at the long-term effects of that reality. Aseptic packaging deals primarily with only a few of the materials shown: LDPE, high-density polyethylene (HDPE), polystyrene, polypropylene, polyester, steel, and aluminum. Figure 6.8 shows the benefit of thermoplastic containers in terms of recoverable Btus available to aid in the incineration process with the additional benefit of providing heat to power steam driven electrical generation systems. Those materials that do not a have a recoverable energy component require energy from other sources to move, distribute, or recondition or

Materials

Million Btu per Ton

Plastics

Polyethylene terephthalatec,e (PET)

20.5

Polyvinyl chloridec (PVC)

16.5

High-density polyethylenee (HDPE) Low-density polyethylene/ Linear low-density polyethylenee (LDPE/LLDPE) Polypropylenec (PP)

Polystyrenec (PS) Othere

Newspaperc Corrugated

cardboardc,d

Mixed papere

19 24.1 38 35.6 20.5 16 16.5 6.7

Glass

0

Steel

0

Aluminum

0

Chapter 6:  Aseptic packaging materials and sterilants

Typical Heat Content of Materials in Municipal Solid Waste (MSW) (Million Btu per Ton)

b: Energy Information Administration, Renewable Energy Annual 2004, “Average Heat Content of Selected Biomass Fuels” (Washington, DC, 2005). c: Penn State Agricultural College Agricultural and Biological Engineering and Council for Solid Waste Solutions, Garth, J. and Kowal, P. Resource Recovery, Turning Waste into Energy, University Park, PA, 1993. d: Bahillo, A. et al. Journal of Energy Resources Technology, “NOx and N2O Emissions during Fluidized Bed Combustion of Leather Wastes,” Volume 128, Issue 2, June 2006, pp. 99–103. e: Utah State University Recycling Center Frequently Asked Questions.

117

Figure 6.8  Recoverable energy content of packaging materials found in municipal waste streams.

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Handbook of aseptic processing and packaging Glass

PE

PET

Alu

Steel

Mass [g]

325

38

25

20

15

Mass/Volume [g/liter]

433

38

62

45

102

Energy/Mass [MJ/kg]

14

80

84

200

23

Energy/Volume [MJ/liter]

8.2

3.2

5.4

9.0

2.4

Container Type

“Embodied Energy of Drink Containers” from the ImpEE resource on “Recycling of Plastics.” A study from the Cambridge–MIT Institute.

Figure 6.9  Energy content per volume (1 liter) of common rigid packages.

reshape them for future use. Figure 6.9 compares the energy cost per volume (liter). With energy costs continually rising, the energy cost advantages have slipped away from all of the traditional packaging materials except steel and that is expected to change to the benefit of plastics in the near future.

chapter 7

Aseptic bulk packaging Thomas Szemplenski

7.1  Aseptic bag-in-box In the early 1970s, William Scholle, an entrepreneur with tremendous foresight, visualized the potential for flexible packaging to replace the expensive, rigid packaging that was being used to transport food products such as tomatoes and other fruit products. Many years prior to this vision, Scholle developed flexible pouches of various propylene derivatives for packaging battery acid. Even today, virtually all battery acid is packaged, transported, and sold in flexible packaging invented by Scholle. Scholle felt that he could use the same packaging technology that was being used to package battery acid to package shelf-stable food products. Instead of using existing retorting technologies to commercially sterilize the product to be packaged in flexible packaging, he leaned toward applying a relatively new technology that was rapidly developing at the time: aseptic processing and packaging. By the early 1970s, the process for aseptically processing food products was proven and commercially operating at approximately a dozen food processing facilities, sterilizing such food products as tomato and fruit pastes, puddings, and dairy-based products. At each of these existing facilities, the aseptically processed product was being aseptically filled into rigid containers using either the Dole aseptic canner or the FranRica aseptic metal drum filler. The can sizes being filled on Dole equipment ranged in sizes from 4 ounces up to the #10 cans that held approximately 96 ounces. The aseptic drum filler aseptically filled product into 55-gallon steel drums. Scholle’s vision was to utilize aseptic processing methods to fill larger quantities for industrial and commercial uses into less expensive flexible packages. At the time, tomato paste and fruit purees and concentrates were hot filled into #10 cans, aseptically packaged into 55-gallon metal drums, or, in the case of fruit products, alternatively filled into plastic pails and frozen for shipment to the end user for reprocessing. All of these

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methods of packaging were expensive, as was the cost of refrigeration when plastic pails were used. Scholle engineered and manufactured a prototype of an aseptic filler to fill preformed bags. The prototype was then installed at the food processing laboratory at Purdue University in West Lafayette, Indiana, and a mutually dependent aseptic processing system was simultaneously installed so a sterile product could be delivered to the filler. Scholle, together with Dr. Phil Nelson, who was then a professor at Purdue, were able to make the necessary modifications to the prototype filler to successfully package high-acid (pH 4.6), and in fact, the most recent low acid filler is a continuous web filler that is capable of filling up to 15 bags per minute. Over the years other companies have manufactured aseptic bag-in-box fillers, however, the Scholle filler remains the dominant market leader for aseptic fillers and supply of preformed flexible bag packaging. Since the formative days for the Scholle aseptic filler in the 1970s, hundreds of aseptic fillers for preformed bags have been installed all over the world and the list of products being aseptically filled into the bags continues to increase. The tomato paste market for aseptic bag fillers was followed by the market for fruit for yogurt and other fruit-based products and citrus products. Some of these products were filled into 3- and 5-gallon bags and others into 55-gallon bags.

7.2  Aseptic bulk container Following aseptic bag-in-box packaging was the development of reusable aseptic stainless steel containers for high-acid products. These containers are usually manufactured in sizes of 200 to 300 gallons and are constructed of either 304 or 316 stainless steel (Figure  7.2). Some of the advantages of this type of aseptic storage include:

Figure 7.2  Stainless steel aseptic tote (800 to 100 liters). (Photograph courtesy of CCR Containers.)

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Figure 7.3  Aseptic totes stacked. (Photograph courtesy of CCR Containers.)

• One-time charge for packaging • Stainless totes are easily sterilized with steam • Ability to remove partial product with remaining product staying sterile • No oxygen or light penetration through flexible packaging • Ability to nitrogen flush the head space • Ability to be stacked high (Figure 7.3) • Able to be cleaned in place • Easily transported by forklift and pallet jacks Products such as diced tomatoes, citrus juices and concentrates, fruit purees, and stabilized fruit for yogurt are some of the products being aseptic packaged and delivered in stainless steel totes. There are a number of suppliers of stainless steel totes. These manufacturers have advised that they will either sell or lease the totes to processors.

7.3  Aseptic bulk storage While working with Scholle to commercialize aseptic bag-in-box technology, Nelson partnered with several other synergistic companies to design and develop equipment to store massive quantities of fruit and vegetable products for long periods at room temperature in bulk holding tanks.

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The more paramount companies that Nelson partnered with included Bishopric Products (now called Enerfab) and FranRica (now called JBT FoodTech). The aseptic processing system is generally the same that is used to process the products for bag-in-box, however, Nelson and his new partners developed a means of epoxy lining carbon steel tanks and sterilizing them so they could be filled and stored with aseptically processed acid products (