Guava Cultivation Antioxidant Properties and Health Benefits

NUTRITION AND DIET RESEARCH PROGRESS

GUAVA CULTIVATION, ANTIOXIDANT PROPERTIES AND HEALTH BENEFITS

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NUTRITION AND DIET RESEARCH PROGRESS

GUAVA CULTIVATION, ANTIOXIDANT PROPERTIES AND HEALTH BENEFITS

ALBERT MURPHY EDITOR

New York

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NOTICE TO THE READER The Publisher has taken reasonable care in the preparation of this book, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained in this book. The Publisher shall not be liable for any special, consequential, or exemplary damages resulting, in whole or in part, from the readers’ use of, or reliance upon, this material. Any parts of this book based on government reports are so indicated and copyright is claimed for those parts to the extent applicable to compilations of such works. Independent verification should be sought for any data, advice or recommendations contained in this book. In addition, no responsibility is assumed by the publisher for any injury and/or damage to persons or property arising from any methods, products, instructions, ideas or otherwise contained in this publication. This publication is designed to provide accurate and authoritative information with regard to the subject matter covered herein. It is sold with the clear understanding that the Publisher is not engaged in rendering legal or any other professional services. If legal or any other expert assistance is required, the services of a competent person should be sought. FROM A DECLARATION OF PARTICIPANTS JOINTLY ADOPTED BY A COMMITTEE OF THE AMERICAN BAR ASSOCIATION AND A COMMITTEE OF PUBLISHERS. Additional color graphics may be available in the e-book version of this book.

Library of Congress Cataloging-in-Publication Data Library of Congress Control Number: 2016962826 ISBN: H%RRN

Published by Nova Science Publishers, Inc. † New York

CONTENTS Preface Chapter 1

Chapter 2

Chapter 3

Chapter 4

Index

vii Guava: The Relationship between the Productive Aspects, the Quality of the Fruits and its Health Benefits Renato de Mello Prado, Jonas Pereira de Souza Junior, Gabriel Barbosa da Silva Júnior and Ítalo Herbert Lucena Cavalcante Guava By-products: A Source of Functional Carbohydrates, Phytochemicals and Enzymes Ying Ping Chang, Nam Weng Sit and Anto Cordelia Tanislaus Antony Dhanapal Residues from Guava Processing: Characterization, Antioxidant Potential and Food Applications Priscilla Siqueira Melo, Miriam Mabel Selani, Severino Matias de Alencar and Carmen J. Contreras-Castillo Guava Fruit Aroma Compounds – State of the Art Research Jorge A. Pino

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PREFACE Guava (Psidium guajava L.), which is considered a native to southern Mexico into Central America extends throughout the South America, Europa, Africa and Asia. It is widely cultivated in tropical and subtropical regions and is becoming increasingly popular worldwide. In this book, Chapter One reviews guava’s productive aspects, quality and health benefits. Chapter Two focuses on the guava by-products’ composition which govern the functional properties. Chapter Three addresses the chemical composition, antioxidant activity and food applications of guava. Chapter Four presents an overview on fundamental and applied aspects related to production of aroma compounds in guava fruit. Chapter 1 - The culture of guava is widely cultivated in tropical regions, where the soil acidity and low nitrogen, phosphorus, and potassium contents are the major limiting factors for crop production. Guava is also cultivated in iron-deficient subtropical regions. Proper cultural management increases fruit production and quality. In this context, the objective of this review is to provide the appropriate measures for sustainable crop management of guava and discuss its benefits to human health. The use of genetically improved guava cultivars associated with the appropriate plant nutrition management decreases the use of pesticides, ensuring greater sustainability in the guava production system. Fertilization optimized guava is dependent on the development stage of the guava plants, soil and leaf analysis results, and production expectations, which might vary with the application of fertilizers in the soil, either in the solid form or through fertigation. Additionally, supplementary fertilization, especially foliar nutrition, might be required as a source of micronutrients.

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Albert Murphy

In soil fertilization, the sustainable use of agro-industrial wastes, such as ash biomass, steel slag and guava fruit pulp have shown promising results. The cultivation of guava with balanced nutrition induces high fruit productivity and quality, with higher post-harvest life and nutritional benefits to human health. Guava contains important antioxidant compounds, which prevent the potential degradation of organic compounds such as amino acids, lipids, fatty acids, and DNA bases, thus preventing the loss of cell integrity due to the formation of lesions. The most important antioxidants present in guava are ascorbic acid (vitamin C), and carotenoids such as lycopene. Moreover, studies have indicated the efficiency of guava in its anti-diabetic, antibacterial and antispasmodic functions. Guava is considered an excellent source of nutrients (calcium, phosphorus, and potassium), which assist in important functions such as the activation of enzymes and development and hardening of bone tissues among others. Furthemore, it acts as a source of vitamin A and B complex, which increase the resistance to virus and prevents the risk of heart attack, stroke, and breast, prostate, and uterus cancers. Chapter 2 - The fruit and vegetable processing industry produces about 0.5 billion tons of waste yearly throughout the world. Handling and disposing of this refuse represents a significant cost and awareness of environmental implications of waste has driven valorization of industrial food by-products. Guavas are rich in vitamins, minerals and fibers. The guava by-product may also possess similar properties. This review focuses on the guava by-products’ composition, which govern the functional properties. The authors anticipate guava by-products could be a source of functional carbohydrates, phytochemicals and enzymes. For a material to be useful on specific applications, the composition-function relation is important. In this review, the authors highlight the potential functions of guava by-products such as hypoglycemic and hypolipidemic properties as well as antimicrobial activity. The authors also emphasize the knowledge gap on guava by-products to foster more research to gain insight on the physicochemical properties of guava byproducts to be applied in various sectors. Chapter 3 - The amount of agro-industrial residues generated worldwide represents a serious environmental problem. In the search for a more sustainable production, an important alternative would be the reuse of these materials, also allowing to add value to them and reduce the costs of their

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treatment. Guava industrial residues, composed mainly of seeds, pulp leftovers and peel, are promising sources of interesting compounds, such as dietary fiber, protein, phenolic compounds, vitamins, minerals, carotenoids and essential fatty acids, which have great potential for use as bioactive compounds and food additives. Considering the great potential of guava processing residue, this chapter will address about its chemical composition, antioxidant activity and food applications. Chapter 4 - This work presents an overview on fundamental and applied aspects related to production of aroma compounds in guava fruit. Using different isolation techniques (distillation, extraction, headspace and sorptive), the volatile compounds have been analyzed in conjunction mainly with gas chromatography-mass spectrometry. In guava fruit, more than 500 volatile compounds have been reported, but only few of these volatiles are considered important contributors to the flavor. Aroma compounds in guava fruit have been reported to be influenced by various factors including maturity stage, varieties, and processing.

In: Guava Editor: Albert Murphy

ISBN: 978-1-53610-767-8 © 2017 Nova Science Publishers, Inc.

Chapter 1

GUAVA: THE RELATIONSHIP BETWEEN THE PRODUCTIVE ASPECTS, THE QUALITY OF THE FRUITS AND ITS HEALTH BENEFITS Renato de Mello Prado, PhD1, Jonas Pereira de Souza Junior1,, Gabriel Barbosa da Silva Júnior, PhD2 and Ítalo Herbert Lucena Cavalcante, PhD3 1

Department of Soils and Fertilizers, UNESP - Univ Estadual Paulista, Jaboticabal, SP Brazil 2 Department of Plant Production, Research Center of Agricultural Sciences, Federal University of Piauí, Teresina, PI, Brazil 3 Collegiate of Agricultural Engineering, Campus of Agricultural Sciences, Federal University of São Francisco Valley, Pretolina, PE, Brazil



E-mail: [email protected].

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ABSTRACT The culture of guava is widely cultivated in tropical regions, where the soil acidity and low nitrogen, phosphorus, and potassium contents are the major limiting factors for crop production. Guava is also cultivated in iron-deficient subtropical regions. Proper cultural management increases fruit production and quality. In this context, the objective of this review is to provide the appropriate measures for sustainable crop management of guava and discuss its benefits to human health. The use of genetically improved guava cultivars associated with the appropriate plant nutrition management decreases the use of pesticides, ensuring greater sustainability in the guava production system. Fertilization optimized guava is dependent on the development stage of the guava plants, soil and leaf analysis results, and production expectations, which might vary with the application of fertilizers in the soil, either in the solid form or through fertigation. Additionally, supplementary fertilization, especially foliar nutrition, might be required as a source of micronutrients. In soil fertilization, the sustainable use of agro-industrial wastes, such as ash biomass, steel slag and guava fruit pulp have shown promising results. The cultivation of guava with balanced nutrition induces high fruit productivity and quality, with higher post-harvest life and nutritional benefits to human health. Guava contains important antioxidant compounds, which prevent the potential degradation of organic compounds such as amino acids, lipids, fatty acids, and DNA bases, thus preventing the loss of cell integrity due to the formation of lesions. The most important antioxidants present in guava are ascorbic acid (vitamin C), and carotenoids such as lycopene. Moreover, studies have indicated the efficiency of guava in its anti-diabetic, antibacterial and antispasmodic functions. Guava is considered an excellent source of nutrients (calcium, phosphorus, and potassium), which assist in important functions such as the activation of enzymes and development and hardening of bone tissues among others. Furthemore, it acts as a source of vitamin A and B complex, which increase the resistance to virus and prevents the risk of heart attack, stroke, and breast, prostate, and uterus cancers.

Keywords: Psidium guajava, quality of fruits, nutrients and vitamins, disease prevention, quality of life

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PRODUCTIVE ASPECTS AND QUALITY OF FRUITS Guava (Psidium guajava L.) is widely cultivated in the tropical regions, where soil acidity (Sanches and Salinas 1983) and low nitrogen, phosphorus, and potassium contents (Crisóstomo and Naumoy 2007) are considered the extremely limiting factors for the cultivation of this fruit. In temperate regions, iron (Fe) deficiency might limit the crop development (Zuo et al. 2011). In plantations established in the tropical soils with high acidity, the proper management of liming is important because it decreases the soil acidity, causes the precipitation of exchangeable aluminum in the soil solution, and provides calcium and magnesium. This might lead to a better development of the root system of plants, and, consequently, better use of the water and nutrients, thus improving the quality of guava fruit (Prato et al. 2005; Natale et al. 2012). For the formation of guava orchards, the deep incorporation of limestone is important because the slow rate of correction of the subsurface layers can compromise crop productivity (Raij et al. 1996). The homogeneous incorporation of the limestone allows a greater contact between the corrective and the acid sources, resulting in a faster effect, thus allowing the better root growth and efficient utilization of water and nutrients contained in the corrected layer (Natale et al. 2012). The use of super heavy gradation is recommended for better distribution of limestone in the soil layer from 0 to 30 cm depth (Prado and Natale 2004). On the other hand, the incorporation of limestone in established guava orchards can damage plants, causing injuries and reduction in root volume, with a consequent risk of an increase in the phytosanitary problems of the crop (Gravena 1993). The superficial application of the corrective acts in the deeper layers of soil gradually neutralizes its acidity by allowing the movement of particles in the soil at a rate of 1 to 2 cm per year, if the humidity and drainage conditions are adequate (Lierop and Westerman 1990). In poorly corrected soil, guava productivity might be impaired at an early stage of cultivation for an extended period of time (Natale et al. 2012). For orchards established in the calcareous and alkaline subtropical soils, iron chlorosis is the most limiting factor for the development of fruit trees (Morikawa et al. 2006); Zuo et al. 2011). In these soils, the high pH and high bicarbonate concentration decrease the solubility of Fe, thus reducing its absorption by the plants (Lucena et al. 2007; Jeong and Connolly 2009). Studies have indicated that the application of inorganic Fe in soil in order to meet the Fe demand of guava has not presented satisfactory results because Fe is quickly converted to a form (FeIII), which is unavailable to plants

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(Vempati and Loeppert 1988; Jeong e Connolly 2009). For example, when FeSO4 is added in a calcareous soil, it quickly reacts with the CaCO3, resulting in the formation of Fe oxides, which are not absorbed by the plant roots (Vempati and Loeppert 1988). As an alternative, the application of synthetic Fe chelates, such as FeEDTA or Fe-EDDHA, has indicate better results in relation to the organic salts of Fe; however, these sources present high costs and with not satisfactory results (Shenker and Chen 2005). Under the conditions of low soil acidity and adequate availability of nutriets, guava presents high yield (Alencar et al. 2016). This, in turn, leads to a high nutrient removal by the crop because of the fruit harvest and pruning operations, which are practiced intensively in the crop, significantly reducing the volume of the aerial plant parts (Thakre et al. 2016; Silva et al. 2016). Although guava has long been considered an acid tolerant plant (Guerrero and Mojica 1991) with a low soil fertility demand (Pereira and Martinez Junior 1986; Guilherme et al. 1986), the rational application of fertilizers promotes a substantial increase in its fruit production (Natale 2009a; Natale 2009b; Alencar et al. 2016). Furthermore, the use of humic substances diluted in water has shown satisfactory results in terms of productivity increase and postharvest quality of fruits grown in orchards with clayey soils (Rocha et al. 2016). The excessive availability of nutrients in the soil, should be avoided during fertilization because it causes an imbalance in the absorption of other elements (Souza et al. 2016; Monte et al. 2016). In the critical phase of fruit development, the relative nutritional imbalance of a given nutrient damages the productivity and quality of guava fruits. Therefore, it is necessary to consider the dynamics of nutrient absorption in plants, which are supplied with high doses of fertilizers (Rozane and Couto 2003). The nutritional requirements of guava are relatively high and, in general, it is a crop cultivated in soils considered to be poor in terms of fertility, making fertilization with almost all the nutrients necessary for its full development (Rozane and Couto 2003). Thus, the export of nutrients becomes an important factor, following the order K > N > P > S > Mg = Ca, which can vary according to the cultivars (Natale et al., 2002; Cavalcante et al. 2008). The guava crop requires the macronutrients in the following decreasing order: N>P>K (Wagh and Mahajan 1988; Chhibba et al. 1987). The use of genetically enhanced guava cultivars associated with adequate nutritional phytosanitary management reduces the use of agricultural pesticides, thus ensuring greater sustainability in the guava crop production

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system. The nutritional status of the crops might affect the productivity and pest resistance in guava and the final composition, size, and post-harvest conservation of its fruit (Aular and Natale 2013). Therefore, it has been shown that the adequate fertilization of guava increases the productivity (Amorim et al. 2015; Alencar et al., 2016) and quality of fruits (Aular and Natale 2013, Bhoyar et al. 2016).

HEALTH BENEFITS Free radicals are reactive oxygen species (ROS) made up of an atom or association of atoms, having an unpaired electron in its outermost orbit (Baxter et al. 2014). They have high energy and kinetic instability; therefore, in order to be stable, it is necessary to donate or accept an electron from another molecule (Sharma et al. 2012). The free radicals produced in the body mainly come from the normal metabolism of oxygen (Valko et al. 2006; Chorilli et al. 2007) that occurs in cytoplasmic organelles (Mignolet-Spruyt 2016). An organism, when exposed to biotic and abiotic stresses, produces free radicals in a quantity greater than its cellular antioxidant capacity (Pandhair and Sekhon, 2006). In this case, the free radicals responsible for promoting plant damage due to the oxidation of various organic compounds, such as lipids, protein, and nucleic acid in plants cells (Leong and Shui 2002), cause a number of degenerative disease (Halliwell and Gutteridge 2015), cancer (Fernandes 2016), and cardiovascular diseases in humans (He et al. 2007). The oxidative stress in plants is related to decreased productivity. In addition, the oxidation of organic substances is a major cause of reduced shelf life of industrialized food products and raw materials (Degáspari and Waszczynskj 2004). Every organism that consumes oxygen is endowed with an antioxidant defense system (Gratão et al. 2005; Gratão et al. 2008), including enzymatic and non-enzymatic components, in order to protect against the damage caused to the macromolecules, such as DNA, lipids, and proteins. Superoxide dismutase, peroxidase glutathione, and catalase are the most important antioxidant enzymes in both humans (Han et al. 2016; Ciattei 2016; Konki et al. 2016) and plants (Nohatto et al. 2016; Zimmermann and Kirsten 2016; Anjum et al. 2016). The non-enzymtic components comprise macromolecules, such as albumin, ceruloplasmin, and ferritin, as well as low molecular weight molecules, such as vitamin C, vitamin E, beta carotene, and reduced glutathione (Jacob 1995; Fang et al. 2002).

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Therefore, lesions caused by free radicals in cells can be prevented or reduce by the activity of the non-enzymatic components of the natural antioxidants found in foods such as guava (Liu et al. 2016), tomato (Talens et al. 2016), grapes (Mendes Lopes et al. 2016), and others. Furthermore, the synthetic antioxidants are used as additives by the food industy to inhibit lipid oxidation, but they can be harmful to human health. Thus, research is focused on the identification of natural antioxidant compounds with the aim of replacing or reducing the use of synthetic antioxidants (Nascimento et al. 2010). The antioxidant capacity of fruits varies depending on the active compounds in then (Saura-Calixto and Goñi 2006). The antioxidants with different chemical properties can work synergistically to protect cells from damage (Blomhoff et al. 2006). Guava has a high content of phenolic compounds, vitamin C (Patel et al. 2016) and lycopene (Oliveira et al. 2011). Lycopene, being one of the most powerful carotenoids with antioxidant actions, is used to prevent carcinogenesis (Jamal et al. 2016), cardiovascular diseases (Sesso et al., 2013), and artherogenesis by protecting molecules such as lipids, low density lipoproteins (LDL), proteins, and DNA (Agarwal and Rao 2000). In addition, guava has a high antioxidant potential (Guo et al. 2003) and regular amounts of acids, sugars, and pectins, which contains tannins, flavonoids, essential oils, sesquiterpenoid alcohols, and triterpenoid acids (Iha et al., 2008). The guava peel exhibits relatively higher antioxidant activity than its pulp, with a FRAP (Ferric ion reducing antioxidant power) value of 10.24, approximately 40% greater than that of the pulp (6.07 FRAP), and approximately 50% greater than that of the seed (4.75 FRAP) (Guo et al. 2003). In addition, the peel might contain significant amount of bioactive compounds, conferring it a high antioxidant potential (Nascimento et al. 2010). Therefore, it should be considered that in the processing of guava, the seeds that are discarded together with a fraction of the peel and pulp not separated in the physical processes of pulping make up the residue that is usually discarded by agribusiness (Guo et al. 2003). These by-products can be considered highly potential raw materials for antioxidants. In general, the daily consumption of fruits as a source of nutrients for ensuring a healthy lifestyle and reducing the risks of chronic diseases has been recommended by the World Health Organization (Huang et al. 2015). Consumers are aware of the need to adapt to healthy diets because an increase

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in the fruit consumption can contribute to an improvement in the longevity and decrease in the incidence of chronic diseases (Conlon et al. 2015). Among fruits, guava presents high antioxidant properties which provide various health benefits (Patel et al. 2016). The beneficial effects of the guava tree are not only limited to its fruit, but are also present in its leaves, which present diverse medicinal properties. The soluble fraction of butanol present in the guava leaves has beneficial effects in the treatment and prevention of type 2 hyperglycemia, which is characterized by the insufficient production of insulin in the pancreas or by the inability of the body to efficiently use the produced insulin. This is due to the fact that the soluble butanol inhibits PTP1B, which is an important mediator of insulin resistance (Oh et al. 2005). Guava leaves have a high concentration of flavonoids and, consequently, it is useful as an alternative for antispasmodic products; therefore, it is accepted and tolerated by adults (Lozoya et al. 2002). The effect of the antispasmodic capacity of its leavez is related to the content of flavonoids, such as those formed by the glycosides derived from quercetin. Quercetin affects smooth muscle fibers by acting as a calcium antagonist, and is the agent responsible for the antispasmodic action of the guava leaves (Galvez et al. 1996). It also has an interesting role as an antioxidant (Manach et al. 2001) and is used in the formulation of antibacterial products, such as 3,4dihydroxybenzoic acid, depending on the peroxity of quercetin (Takahama and Hirota 2001). Quercetin in the guava leaves also presents important antidiarrheal properties (Zhang et al. 2003). Quercetin-3-arabinoside causes the inhibition of acetylcholine release together with an initial increase in the muscle tone, thus decreasing spontaneous contraction (Lutterodt 1989). Lectin, a specific galactose present in the guava leaf, demonstrates an inhibitory effect on the development of Escherichia coli, an agent that causes diarrhea in organisms by preventing its adhesion to the gut wall (Coutiño et al. 2001). The alcoholic solution prepared with guava root and leaves combats the development of several microorganisms, such as Staphylococcus aureus, Bacillus cereus, and Proteus spp. (Chah et al. 2006). This is mainly due to the presence of the antibacterial derivatives of quercetin (Prabu et al. 2006). Guava also has a high parasite lactate dehydrogenase (pLDH) indez, which is a newly developed in vitro indicator to measure the capacity of efficient components in the treatment of malaria, evidencing the beneficial result of guava intake in the treatment of this disease (Nundkumar and Ojewole 2002).

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The essential oils present in guava leaf significantly decrease the growth of human squamous cell carcinoma (Chen et al. 2007) and inhibit its proliferative action (Manosroi et al. 2006) due to the monoterpenes present in these compounds (Citó et al. 2003)). It has also been reported that fumaric acid in guava has caused a decrease in the incidence of tumors (Numata et al. 1989). The ingestion of guava fruits causes a reduction in the levels of phosphates and malondeides in the heart (Conde et al. 2003), protecting against myocardial damage because the endogenous antioxidants help maintain high levels of antioxidants in the myocardium, resulting in a significant restoration of most hemodynamic parameters, which contribute to the cardiopretective effect of this fruit (Yamashiro et al. 2003). In view of the above information, it is evident that the guava crop should be managed properly with efficient liming and fertilization and correct cultural practices, thus guaranteeing adequate nutrition, aiming at a better quality production with more nutritious and healthy fruits. The better quality of the guava fruits contributes to an increase in the daily consumption of this fruit in natural form. Thus, the diverse chemical properties of guava, including its antioxidant action, reflect in the reduced incidence of several diseases and consumption of pharmaceuticals, contributing to the maintenance of healthier lifestyle.

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Guilherme, M. R., Queiroz, E. D., Campelo Junior, J. H., Vieira, A., Rodriguez, A. P. M. (1986). Nutrição mineral e adubação de frutíferas tropicais. Campinas: Fundação Cargil. Guo, C., Yang, J., Wei, J., Li, Y., Xu, J., Jiang, Y. (2003) Antioxidant activities of peel, pulg and seed fractions of common fruits as determined by FRAP assay, Nutrition Research, 23, 1719-1726. Halliwell, B., Gutteridge, J. M. (2015). Free radicals in biology and medicine. Oxford University Press, USA. Han, Y. H., Buffolo, M., Pires, K. M., Pei, S., Scherer, P. E., Boudina, S. (2016). Adipocyte-Specific Deletion of Manganese Superoxide Dismutase Protects from Diet-Induced Obesity Via Increased Mitochondrial Uncoupling and Biogenesis. Diabetes, db160283. He, F., Nowson, C., Lucas, M., Macgregor, G. (2007). Increased consumption of fruit and vegetables is related to a reduced risk of coronary heart disease: Metaanalysis of cohort studies. Journal of Human Hypertension, 21, 717-782. Huang, X. and Hsieh, F. H. (2005) Physical Properties, Sensory Attributes, and Consumer Preference of Pear Fruit Leather. Journal of Food Science, 70, E177-E186. Iha, S. M., Migliato, K. F., Vellosa, J. C., Sacramento, L. V. S., Pietro, R. C., Isaac, V. L. B., Salgado, H. R. N. (2008). Estudo fitoquímico de goiaba (Psidium guajava L.) com potencial antioxidante para o desenvolvimento de formulação fitocosmética. Revista brasileira de farmacognosia, 387393. Jacob, R. A. (1995). The integrated antioxidant system. Nutrition research, 15, 755-766. Jamal, P., Akbar, I., Yumi, Z., Irwandi, J. (2016). Process Development for Maximum Lycopene Production from Selected Fruit Waste and its Antioxidant and Antiradical Activity Journal of Food Processing and Technology, 7, 1-7. Jeong, J., Connolly, E. L. (2009). Iron uptake mechanisms in plants: functions of the FRO family of ferric reductases. Plant Science, 176, 709-714. Johnston, P. C., McCance, D. R., Holmes, V. A., Young, I. S., McGinty, A. (2016). Placental antioxidant enzyme status and lipid peroxidation in pregnant women with type 1 diabetes: The effect of vitamin C and E supplementation. Journal of diabetes and its complications, 30, 109-114.

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Konki, M., Pasumarthy, K., Malonzo, M., Sainio, A., Valensisi, C., Söderström, M. Laiho, A. (2016). Epigenetic Silencing of the Key Antioxidant Enzyme Catalase in Karyotypically Abnormal Human Pluripotent Stem Cells. Scientific reports, 6. Leong, L. P., Shui, G. (2002). An investigation of antioxidant capacity of fruits in Singapore markets. Food chemistry, 76, 69-75. Lierop, W. V., Westerman, R. L. (1990). Soil pH and lime requirement determination. Soil testing and plant analysis, 73-126. Liu, Y., Ko, E. J., Yoo, J. H., Song, E. K., Kim, H. S. (2016). The effect of guava leaf extracts on antioxidant properties and lipid profile in ovariectomized rats. The FASEB Journal, 30, 692-16. Lozoya, X., Reyes-Morales, H., Chávez-Soto, M. A., Martınez-Garcıa M., Soto-González, Y., Doubova, S. V. (2002). Intestinal anti-spasmodic effect of a phytodrug of Psidium guajava folia in the treatment of acute diarrheic disease. Journal of Ethnopharmacology, 83, 19-24. Lucena, C., Romera, F. J., Rojas, C. L., García, M. J., Alcántara, E., PérezVicente, R. (2007). Bicarbonate blocks the expression of several genes involved in the physiological responses to Fe deficiency of Strategy I plants. Functional plant biology, 34, 1002-1009. Lutterodt, G. D. (1989). Inhibition of gastrointestinal release of acetylcholine by quercetin as a possible mode of action of Psidium guajava leaf extracts in the treatment of acute diarrhoeal disease. Journal of Ethnopharmacology, 25, 235–247. Manach, C., Morand, C., Remesy, C., Crespy, V. (2001). Querectin 3-o-betaglucoside is better absorbed that other quercetin derivatives and is not present in rat plasma. Free radical Research, 33, 667-676. Manosroi, J., Dhumtanom, P., Manosroi, A. (2006). Anti-proliferative activity of essential oil extracted from Thai medicinal plants on KB and P388 cell lines. Cancer letters, 235, 114-120. Mendes Lopes, M. L., Miguel, M. A. L., Fialho, E., Valente‐Mesquita, V. L. (2016). Grape juice obtained using steam extraction and other small‐scale extraction methods: phenolic content, antioxidant capacity and stability during storage. International Journal of Food Science and Technology. Mignolet-Spruyt, L., Xu, E., Idänheimo, N., Hoeberichts, F. A., Mühlenbock, P., Brosché, M., Van Breusegem, F., Kangasjärvi, J. (2016). Spreading the news: subcellular and organellar reactive oxygen species production and signaling. Journal of Experimental Botany, 1-14.

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Montes, R. M., Parent, L. E., Amorim, D. A., Rozane, D. E., Parent, S., Natale, W., Modesto, V. C. (2016). Nitrogen and Potassium Fertilization in a Guava Orchard Evaluated for Five Cycles: Effects on the Plant and on Production Revista Brasileira de Ciencia do Solo, 40, e0140532. Morikawa, C. K., Saigusa, M., Nakanishi, H., Nishizawa, N. K., Mori, S. (2006). Overcoming Fe deficiency in guava (Psidium guajava L.) by cositus application of controlled release fertilizers. Soil Science and Plant Nutrition, 52, 754-759. Nascimento, R. D., Araújo, C. D., Melo, E. D. A. (2010). Antioxidant from agri-industrial wastes of the guava fruits (Psidium guajava L.). Alimentos e Nutrição Araraquara, 21, 209-216. Natale, W. (2009b) Adubação, nutrição e calagem na goiabeira: Cultura da goiaba do plantio à comercialização. Jaboticabal:FCAV/Capes/CNPq/ FAPESP/Fundunesp/SBF. Natale, W., Coutinho, E. L. M. Pereira, F. M., Boaretto, A. E. (2002). Nutrients foliar content for high productivity cultivars of guava in Brazil. Acta Horticulturae, 1, 383-386. Natale, W., Coutinho, E. L. M., Pereira, F. M., Martinez Junior, M., Martins, M. C. (2009a). Efeito da adubação N, P e K no teor de sólidos solúveis totais de frutos de goiabeira (Psidium guajava L.). Alimentos e Nutrição Araraquara, 6. Natale, W., Rozane, D. E., Parent, L. E., Parent, S. É. (2012). Acidez do solo e calagem em pomares de frutíferas tropicais. Revista Brasileira de Fruticultura, 1, 1294-1306. Nohatto, M. A., Agostinetto, D., Langaro, A. C., de Oliveira, C., Ruchel, Q. (2016). Atividade antioxidante de plantas de arroz pulverizadas com herbicidas. Pesquisa Agropecuária Tropical (Agricultural Research in the Tropics), 46, 28-34. Numata, A., Yang, P., Takahashi, C., Fujiki, R., Nabae, M., Gujita, E. (1989). Cytotoxic triterpenes from Chinese medicine, Goreishi. Chemical and Pharmaceutical Bulletin, 37, 648-651. Nundkumar, N., Ojewole, J. A. (2002). Studies on the antiplasmodial properties of some South African medicinal plants used as antimalarial remedies in Zulu folk medicine. Methods and Findings in Experimental and Clinical Pharmacology, 24, 397–401. Oh,W. k., Lee, C. H., Bae, E. Y., Sohn, C. B., Oh, H., Kim, B. Y., Ahn, J. S. (2005) Antidiabetic effects of extracts from Pisidium guajava. Journal of Ethno-pharmacology, 96, 411-414.

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Oliveira D. S., Aquino, P. P., Ribeiro, S. M. R., da Costa Proença, R. P., Pinheiro-Sant'Ana, H. M. (2011). Vitamina C, carotenoides, fenólicos totais e atividade antioxidante de goiaba, manga e mamão procedentes da Ceasa do Estado de Minas Gerais. Acta Scientiarum Health Sciences, 33, 89-98. Pandhair, V., Sekhon, B. S. (2006). Reactive oxygen species and antioxidants in plants: an overview. Journal of plant Biochemistry and Biotechnology, 15, 71-78. Patel, P., Ellis, K., Sunkara, R., Shackelford, L., Ogutu, S., Walker, L. T., Herring, J. and Verghese, M. (2016) Development of a Functional Food Product Using Guavas. Food and Nutrition Sciences, 7, 927-937. Pereira, F. M., Martinez Junior, M. (1986). Goiabas para industrialização. Jaboticabal: Legis Summa. Prabu, G. R., Gnanamani, A., Sadulla, S. (2006). Guaijaverin a plant flavonoid as potential antiplaque agent against Streptococcus mutans. Journal of Applied Microbiology, 101, 487–495. Prado, R. M., Natale, W. (2004). Uso da grade aradora superpesada, pesada e arado de disco na incorporação de calcário em profundidade e na produção do milho. Engenharia Agrícola, 24, 167-176. Prado, R. M., Natale, W., Silva, J. A. A. (2005) liming and quality of guava fruit cultivated in Brasil. Scientia Horticulturae, 104, 6, 91-102. Raij, B. V., Cantarella, H., Quaggio, J. A., Furlani, A. M. C. (1996) Recomendações de adubação e calagem para o Estado de São Paulo. Campinas: Instituto Agronômico and Fundação IAC. Rocha, L. F., Cavalcante, L. F., Nunes, J. C., Souto, A. J. L., Cavalcante, A. C. P., Cavalcante, Í. H. L., Pereira, W. E. (2016). Fruit production and quality of guava ‘Paluma’ as a function of humic substances and soil mulching. Agrican Journal of Biotechnology, 15, 1962-1969. Rozane, D. E; Couto, F. D. A. (2003). Cultura da goiabeira: tecnologia e mercado. Viçosa:UFV. Sanches, P. A., Salinas, J. G. (1983) Suelos ácidos:estratégias para su manejo com bajos insumos em America Tropical. Bogotá: Sociedad colombiana de la Ciencia del Suelo. Saura-Calixto, F., Goñi, I. (2006). Antioxidant capacity of the Spanish Mediterranean diet. Food Chemistry, 94, 442-447. Sesso, H. D., Liu, S., Gaziano, J. M., Buring, J. E. (2003). Dietary lycopene, tomato based food products and cardiovascular disease in women. Journal of Nutrition, 133, 2336- 2341.

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Sharma, P., Jha, A. B., Dubey, R. S., Pessarakli, M. (2012). Reactive oxygen species, oxidative damage, and antioxidative defense mechanism in plants under stressful conditions. Journal of Botany, 2012. Shenker, M., Chen, Y. (2005). Increasing Iron Availability to Crops: Fertilizers, Organo‐Fertilizers, and Biological Approaches. Soil Science and Plant Nutrition, 51, 1-17. Silva, M. J. R., Tecchio, M. A., Domiciano, S., Leonel, S., Balestrero, R. I. (2016). Phenology, yield and fruit quality of ‘Paluma’ guava tree at different pruning times Fenologia, produção e qualidade de frutos da goiabeira ‘Paluma’ em diferentes épocas de poda. Ciência e Agrotecnologia, 40, 317-325. Souza, H. A., Étienne Parent, S., Rozane, D. E., Amorim, D. A., Modesto, V. C., Natale, W., Parent, L. E. (2016). Guava Waste to Sustain Guava (Psidium guajava) Agroecosystem: Nutrient “Balance” Concepts. Frontiers in Plant Science, 7, 1-13. Takahama, U., Hirota, S. (2001). Deglucosidation of quercetin glucosides to the aglycone and formation of antifungal agents by preoxidase-dependent oxidation of quercetin. Plant and Cell Physiology, 41, 1021-1029. Talens, P., Mora, L., Bramley, P. M., Fraser, P. D. (2016). Antioxidant compounds and their bioaccessibility in tomato fruit and puree obtained from a DETIOLATED-1 (DET-1) down-regulated genetically modified genotype. Food Chemistry, 213, 735-741. Thakre, M., Lal, S., Uniyal, S., Goswami, A. K., Prakash, P. (2016). Pruning for crop regulation in high density guava (Psidium guajava L.) plantation. Spanish Journal of Agricultural Research, 14, 1-8. Valko, M., Rhodes, C. J., Moncol, J., Izakovic, M. M., Mazur, M. (2006). Free radicals, metals and antioxidants in oxidative stress-induced cancer. Chemico-biological interactions, 160, 1-40. Vempati, R. K., Loeppert, R. H. (1988). Chemistry and mineralogy of Fe‐ containing oxides and layer silicates in relation to plant available iron. Journal of plant nutrition, 11, 1557-1574. Wagh, N. A., Mahajan, P. R. (1988). Effect of NPK fertilization on leaf nutrient status of sardar guava. Journal of Maharastra Agricultural University, 13, 111-112. Yamashiro, S., Noguchi, K., Matsuzaki, T., Miyagi, K., Nakasone, J., Sakanashi, M., Aniya, Y. (2003). Cardioprotective effects of extracts from Psidium guajava L. and Limonium wrightii, Okinawan medicinal plants, against ischemia-reperfusion injury in perfused rat hearts. Pharmacology, 67, 128-135.

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In: Guava Editor: Albert Murphy

ISBN: 978-1-53610-767-8 © 2017 Nova Science Publishers, Inc.

Chapter 2

GUAVA BY-PRODUCTS: A SOURCE OF FUNCTIONAL CARBOHYDRATES, PHYTOCHEMICALS AND ENZYMES Ying Ping Chang1,, Nam Weng Sit2 and Anto Cordelia Tanislaus Antony Dhanapal1 1

Department of Chemical Science, Faculty of Science, Universiti Tunku Abdul Rahman, Kampar, Malaysia 2 Department of Biomedical Science, Faculty of Science, Universiti Tunku Abdul Rahman, Kampar, Malaysia

ABSTRACT The fruit and vegetable processing industry produces about 0.5 billion tons of waste yearly throughout the world. Handling and disposing of this refuse represents a significant cost and awareness of environmental implications of waste has driven valorization of industrial food by-products. Guavas are rich in vitamins, minerals and fibers. The guava by-product may also possess similar properties. This review focuses on the guava by-products’ composition, which govern the functional properties. We anticipate guava by-products could be a source 

Corresponding Author: [email protected].

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Y. P. Chang, N. W. Sit and A. C. T. A. Dhanapal of functional carbohydrates, phytochemicals and enzymes. For a material to be useful on specific applications, the composition-function relation is important. In this review, we highlight the potential functions of guava by-products such as hypoglycemic and hypolipidemic properties as well as antimicrobial activity. We also emphasize the knowledge gap on guava by-products to foster more research to gain insight on the physicochemical properties of guava by-products to be applied in various sectors.

Keywords: enzymes, phytochemicals

functional

carbohydrates,

guava

by-products,

INTRODUCTION Guava (Psidium guajava Linn.) is famous for its food and nutritional values. It contains high amount of valuable nutritional constituents such as dietary fiber, vitamins, dietary minerals and other nutrients. This makes guava popularly referred to as “superfruits.” Guava belongs to the Myrtaceae family and Psidium genus. The common guava (Psidium guajava) is cultivated in many tropical and subtropical countries. The Food and Agriculture Organization recorded around 5.2 million metric tons of fresh guava production in 2010 [1]. The global production increased to 6.2 million metric tons in 2013 [2] with India, Pakistan and Brazil as the top three guava producers. Even though Malaysia is not a major fruit exporter, about 20% of pink guava puree market in the world is supplied by Malaysia [3]. Perak state has the biggest guava plantation among the states in Malaysia [4]. Fresh guava spoils rapidly once it is harvested, and is widely processed to extend the shelf life. Products produced and originated from the guava industry include beverages, syrup, ice cream, jam, jellies, cheese, toffee, juice, wine and canned products [5]. Most of the export trade in processed guava is in the form of concentrate and pulp. Thus, large amounts of seed, peel and pomace are produced from the industry. These by-products may contain similar chemical constituents, though in different amounts if compared to those of the processed counterpart. To minimize ‘waste’ in guava product manufacturing, these by-products are to be evaluated so that their beneficial compositions and properties can be maximized. Making use of underutilized by-products is economically attractive since it lessens the problem of industrial fruit wastes and provides additional products to the industries and consumers. The term ‘valorize’ means the

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progress of creating value from knowledge towards waste or by-products into a product which is suitable, available and being recognized by the economy and society [6]. The major challenge of re-using waste materials is the variability and complexity in its composition. Composition and functional properties are among the factors that govern the values of the wastes. For instance, waste that comprises high fat and protein content may be appropriate as a nutrient source for the nourishment of animals. Cattles can feed with suitable amounts of cellulose-rich wastes as they have the digestive capacity. Wastes with great proportions of minerals such as pomace are suitable as natural fertilizers. Pomace (seed, stalk, and skin) and hop wastes (brewing waste) are not good options for animal feed because of the high levels of phenolic compound and pesticides present. Plant-based waste products may also be used as a food ingredient. Oreopoulou and Tzia [7] suggested the utilization of fibrous materials as food additives because of their high absorptive properties and gelling abilities. Malaysia, which is one of the leading countries in producing guava puree, discards about 25% of the pink guava by-products [8]. The production of pink guava puree (Figure 1) removes three main waste products: refiner, siever and decanter [9]. Refiner, obtained from the crushing process, consists mainly of guava seeds and coarse pulp that comprises 12% of the guava fruit. The siever (8%) has many pulpy bits, and the 5% of decanter consists of guava stone cells. Amin and Mukhrizah [10] suggested that guava wastes can be a source of antioxidant compounds, natural additives and functional fruit ingredients. In addition, Kong and Ismail [11] stated that the pink guava by-products are likely to protect cell damage that is induced by hydrogen peroxide (H2O2). In this review, we focus on the guava by-products’ constituents, which govern the functional properties for applications in various fields. We anticipate guava by-products could be a source of functional carbohydrates, phytochemicals and enzymes. These constituents are important to be applied in various sectors and exert different technological functions or health-promoting activities. They are liable to be modified by various treatments for improving the bioactivities and functions. Lastly, we highlighted research gaps on guava byproducts for the applications in various fields.

THE POTENTIAL VALUES OF GUAVA BY-PRODUCTS As reported by Fernández-López et al. [12] plant based by-products can be further processed to food additives, food supplements, animal feed or biofuel,

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depending on their composition [13]. Our previous research found that guava by-products such as seeds are rich in dietary fiber [14]. In this subsection we present and discuss documented findings on functional carbohydrates, phytochemicals and enzymes from guava or guava by-products.

FUNCTIONAL CARBOHYDRATES Carbohydrates are the most abundant constituents found in plant-based material. There are three categories of carbohydrates based on degree of polymerization (DP), which are monosaccharides (DP1-2), oligosaccharides (DP 3-9) and polysaccharides (DP ≥ 10). Carbohydrates can be classified based on the function too: Structural and non-structural. Examples of structural carbohydrates include cellulose, hemicelluloses and lignin. They provide support to maintain the structure of the plant. On the contrary, nonstructural carbohydrates are meant for storage purposes and fuel metabolism. Insoluble starches, water-soluble carbohydrates, sucrose and oligosaccharides are some examples of non-structural carbohydrates.

Figure 1. Pink guava puree processing and by-products produced [9].

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Dietary fiber is the edible part of plant materials that are resistant to digestion and absorption in the small intestine but undergo complete or partial fermentation in the large intestine [15]. Thus, dietary fiber-rich materials usually show low digestibility. The total dietary fiber consists of two major fractions: water-soluble and water-insoluble. Water-soluble dietary fiber consists of pectin and gums, while water-insoluble dietary fiber consists of cellulose, hemicelluloses and lignin [16]. Guava is one of the richest sources of dietary fiber. Reports by JimenezEscrig et al. [5] and Martínez et al. [17] reaffirmed this fact that guava concentrate and by-products possess high dietary fiber content (up to 69.1 g/100 g dry matter) and exhibit antioxidant activity (up to 462 μmolTrolox eq./g dry matter). Gorinstein [18] cited that guava fruits have a high content of total and soluble dietary fibers, amounting to 5.60 and 2.70 g/100g respectively. Munhoz et al. [19] found that low esterified pectin was obtained from the flour of guava pulp. Guava by-products apparently have more insoluble dietary fiber than soluble dietary fiber and show best functional properties compared with other tropical fruits by-products [20]. Guava pomace refers to waste produced after the fruit juice manufacturing which consists of a mixture of peel, seed and pulp. Siddiq [8] reported that guava pomace produced from the juice production is a good source of fiber (40.98%) and vitamin C (19.57 mg/100 g). Goñi and Hervert-Hernández [21] reported that guava by-products consist of a total dietary fiber of 48.6 g/100g dry weight. These functional properties have undoubtedly made them one of the best value-added products in baking industries [22] and poultry farming [23]. The dietary fiber composition of guava is enumerated in Table 1. The various constituents of dietary fiber identified in guava by-products are rhamnose, fucose, arabinose, xylose, mannose, uronic acids, klason lignin and pectins. Dietary fiber-rich material is desirable of its physicochemical properties. These physicochemical properties have been more useful for understanding the physiological effect of dietary fiber than the chemical composition alone [24]. Dietary fiber is well known to exert health-promoting effects upon consumption of the host. The positive effects of a fiber-rich diet include smooth intestinal transit and the prevention of diabetes, cardiovascular diseases and colon cancer [25].

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Y. P. Chang, N. W. Sit and A. C. T. A. Dhanapal Table 1. Dietary fiber composition of guava

Dietary fiber constituent Rhamnose (%)

Parts of Guava Plant peel pulp Fucose (%) peel pulp Arabinose (%) peel pulp Xylose (%) peel pulp Mannose (%) peel pulp Galactose (%) peel pulp Glucose (%) peel pulp Total Neutral sugars (%) peel pulp Uronic acids (%) peel pulp Klason lignin (%) peel pulp Dietary fiber (%) peel pulp Crude fiber (%) fruit flour Pectin (g/100g) seed (powder) Total Dietary Fiber (g/100g) seed (powder) Dietary fiber whole fruit (unripen) Dietary fiber co-products * % on dry matter basis

Amount Present 0.49 ± 0.18* 0.53 ± 0.02* 0.27 ± 0.01* 0.20 ± 0.01* 2.26 ± 0.34* 1.89 ± 0.34* 11.31 ± 1.02* 11.51 ± 2.01* 0.52 ± 0.13* 0.53 ± 0.11* 0.59 ± 0.12* 0.80 ± 0.13* 12.06 ± 1.10* 13.08 ± 0.97* 27.51 ± 1.60* 28.54 ± 2.25* 2.49 ± 0.10* 2.45 ± 0.11* 18.55 ± 0.57* 18.47 ± 0.31* 48.55 ± 2.16* 49.42 ± 2.25* 11.9 ± 0.05 12.7 ± 0.05 0.58 ± 0.01 63.94 ± 0.10 43.21 ± 0.09 69.1 ± 0.17

Source [5]

[30] [31] [20] [17]

Commonly measured physicochemical properties of dietary fiber include water holding, oil holding, cation exchanging, glucose diffusion retardation index and bile acid binding [26]. The water holding capacity (WHC) of a fiber is a measure of the ability of a fiber source to immobilize the water within its matrix [27]. The net effects would be an increase in stool weight, causing dilution of the intra-luminal contents, speeding up the materials to be excreted.

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This limits the gut exposure to toxins or other harmful agents and exerts anticonstipation effect. Fibers also retain and trap the oil components during the digestion and the oils are excreted out of the body with the fiber. Thus, this lessens the absorption of excessive fats and oils in the small intestine. The cation exchange capacity (CEC) is directly contributed by functional groups of fiber, such as pectins, phenolics, lignin and tannin. These components are negatively charged and have high affinity on cations [28] such as hydrogen ions or other metal ions in the gut. Thus, the pH of the gut will be less acidic because of decreasing concentration of acidic H+ ions. However, high cation exchange capacity may bring deleterious effects as some essential micronutrients such as calcium and iron may also bind to the fiber, resulting in the excretion of minerals and electrolytes through the feces and lead to mineral deficiency [29]. The advantages of dietary fiber incorporation in one’s diet would be the binding properties that lead to hypoglycemic and hypocholesterolemic effects. The potential hypocholesterolemic properties of dietary fiber in managing metabolic disorder such as overweight and obesity are well documented in various studies. Upon consumption, the dietary fibers swell and gel in the presence of water and peristalsis action to trap the bile acids secreted inside the gastrointestinal tract. This may help in minimizing the contact of bile acids and dietary cholesterol and the reabsorption of bile acids into the body [32]. Eventually, this prevents the dietary cholesterol to be digested by bile acids. Therefore, the body experiences an overall hypocholesterolemic effect resulted from consuming dietary fibers. Meanwhile, dietary fibers also exert hypoglycemic effects through several mechanisms: (a) increasing the viscosity of digestive juice in the small intestine and thus delaying glucose diffusion [33]; (b) binding with glucose which causes decreased availability of glucose in small intestine [34]; and (c) retarding α-amylase action by capsuling starch and the enzyme respectively [35-36]. Another important physiological effect by indigestible dietary fibers is the ability to endorse the growth of beneficial gut bacteria to ferment it into short chain fatty acids [37]. This kind of dietary fiber is known as prebiotics. Gastrointestinal bacteria, which improve human immune system and provide protection against pathogens, are known as probiotics. Probiotics help to lower the exposure risk to obesity, type 2 diabetes, colon cancer, inflammatory bowel disease and autoimmune disease. Not all dietary fibers are prebiotics. Prebiotics resist digestion in the stomach and small intestine but are fermented in the large intestine.

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A literature search revealed that prebiotic carbohydrates can be found in cereals, legumes, fruits and vegetables besides root and tuber crops. For example, garlic, Jerusalem artichoke, onion and shallot are among the vegetables; dragon fruit, jackfruit, nectarine and palm fruit are among the fruits; chicory and yaconare are among the root crops, which possess prebiotic activity. Barley, chickpea, lentil and wheat from cereal and legume crops also show genetic variability for prebiotic carbohydrates [38]. Reports about prebiotic activity of guava or guava by-products are scanty, which warrants further research.

PHYTOCHEMICALS Phytochemicals refer to bioactive compounds produced by plants through their secondary metabolism. These phytochemicals may elicit a long range of different effects on the hosts upon consumption, dependent on plant species and amount eaten. As reviewed by Bernshoft [39], the main phytochemicals found in different plants include glycosides, glucosinolates, saponins and phenylpropanoids, such as flavonoids, tannins, proanthocyanidins and terpenes such as sesquiterpenes and monoterpenes besides alkaloids and peptides. Plants that are rich in these phytochemicals are often characterized as both poisonous and medicinal. This suggests that a beneficial or an adverse effect may depend on the amount eaten. Processing tropical exotic fruits involves separating the desired valuable fruit product from other constiuents of the plant tissue like the peel and seed. These by-products contain high levels of various phytochemicals and may apply as food additives, like antioxidants (prevent browning and lipidoxidation and as functional food ingredients), antimicrobials, flavoring, colorants and texturizer additives [40]. Seeds are 6% to 12% of the guava fruit weight [41]. Guava seeds contain 9.1% to 10.5% fat on a dry weight basis [42-44]. The fatty acid composition was similar to that of cottonseed oil [43] or safflower oil [45]. Palmitic acid is the major saturated fatty acid, while linoleic acid is the major unsaturated fatty acid in guava seed oil [45, 46]. The seed protein percentage has been reported as 9.37% to 9.73% on a dry weight basis [43, 44, 46]. Glutelins (86–90 g/100 g) and globulins (~10 g/100 g) constitute the main components of guava seed storage proteins, whereas albumins and prolamins are the minor components (~2 g/100 g) [47]. There are 15 amino acids found of which 67% are contributed by arginine, glutamic acid, aspartic acid, glycine and leucine [48]. Leucine is the predominant essential amino acid with a value of 2.2 mg/g,

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while the major non-essential amino acid is glutamic acid of 6.2 mg/g [46]. The essential amino acid profile of the guava seed protein isolate, except for lysine content, is above that proposed in the FAO/WHO pattern for adults [49]. Guava seed oil is rich in phytosterols, with stigmasterol accounting for 97% of total sterols. Campesterol is detected at 9.9 mg/100 g of seed oil, while -sitosterol and -5 avenasterol are present in traces amounts (