Microwave Heating

 

Microwave   welcomes  You..

 

 

Facts and statistics.. Agricultural Agricultural production production during during 2001-02 2001-02 was 209MT.  

Agro and food processing sector ranks fifth in India’s GDP. GDP.   Employs around 18% of country’s industrial force.

  Export growth from 2,821cr (91-92) to 10,770cr (2000-01).   Largest live stock population in the world.  

producer of fruit   Second, fifth and sixth largest [ The Hindu oct-12, 2002 ]

 

Weakness of Indian food sector..

ow processing levels High wastage levels leading to llow level High seasonability & perishability – low profit margi Lack of requisite packaging quality and presentabili required for marketing. Lack of ready acceptance in international marketing Higher cost of processing [12,2002 The Hindu oct]  

 

Microwave (MW) Processing.. Processing..  MW heating refers electromagnetic electr omagnetic agnetic electrom

to

use

of non-ionizing waves of certain

freq frequencies uencies ncies to generate heat in material. freque

 Microwave processing results in excellent retention of nutritional and sensory value besides having other advantages like saving in energy, cost, time, etc

 

  The speed with which heating takes place in the

 

UNIQUENESS OF MICROWAVE HEATING TECHNOLOGY 

  Speed Speed::

Processes taking hours by conventional means

are possible in few minutes by mw processing. 

 Uniform

volumetric

heating: heating:

Heat

is

generated

uniformly throughout the entire substance  Self

regulating and differential heating

 Efficiency Efficiency::

Efficiency higher than 70%



 Instantaneous control  

 Lower cost: cost: Reduction in processing time thus saving

 

Electromagnetic spectrum and their applications

Available MW Frequencies 915 MHz ± 13 MHz 2450 MHz ± 50 MHz 5800 MHz ± 75 MHz 24125 MHz ± 125 MHz

Frequency range 300MHz – 300GHz

Corresponding wavelengt 1m – 1mm  

 

Heating mechanism..

  Accomplished by Absorption tion    Absorp Absorptio n

of mw energy by water molecules (Dipolar rotation) (Tries to align with changing polarity- 2.45 b times / sec ,generates heat)  Translation Translation of  ionic components of foods (Ionic conduction)



 

Effect of electromagnetic radiation on dipoles

 

Critical Process Factors in Microwave Heating

Food

Shape, size, composition (moisture, salt), liquid against solid multiple components (as in a frozen dinner),

Package

Presence of metallic elements such as aluminum foil, susceptor

Process

Power level, cycling, presence of hot water or air around the food, equilibration time

Dimensions, shape and other electromagnetic characteristics Equipment of the oven, frequency, agitation of the food, presence of mode stirrers and turntables

 

 

Conventional Vs microwave heating..  Surface heating  Slow process  Low thermal efficiency

  Volumetric heating  Rapid heating  High thermal Efficiency

mw oven-40% electric oven - 14% gas oven - 7%

 Uniform Heating

 Non-unifor Non-uniformity mity Non-uniformi ty heating

Moisture removal (