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M icrowave Processing

Food irradiation

High hydrostatic pressure

Microwave heating

Pulsed electric field




Quality Management in Fish Processing

Properties of foods

Heat transfer In Food

Water activity

Fruit and juice processing

Carbohydrate and intense sweeteners Used In soft driks

Ingredients used in soft drinks

Non-carbonated beverages

Processing and packaging of Soft drinks


Microwave heating refers to the use of electromagnetic waves of certain frequencies to generate heat in a material. Industrial food microwaves use only 2450 and 915 MHz


In microwave heating, continuous electromagnetic waves are produced in the magnetron and transmitted through a hollow metallic tube into a resonant cavity where the food is processed. Foods are heated because of molecular friction caused by alternating polarization of molecules. Foods absorb microwave energy in the form of orientational and ionic polarization. Orientational polarization results from dipolar molecules, such as water, which tend to align according to the applied electric field. The electric field oscillates at 2450 or 915 million times per second (MHz), making the dipolar molecules rotate, thus promoting molecular friction, which in turn results in heat dissipation. Ionic polarization occurs when dissolved salts are present. Positive and negative ions tend to migrate to opposite-charged regions, colliding with other ions and converting kinetic energy into heat. Dipole rotation is more important than ionic polarization as a microwave heating mechanism.

Effects of Microwaves on Microbial Inactivation

Heat sensitive nutrients such as vitamins and flavor constituents can be retained better through rapid heating than by conventional heat treatments. However, little conclusive evidence exists for any real flavor differences between many conventionally and microwave-heated foods microwave energy inactivates microbes via conventional thermal mechanisms, including thermal irreversible denaturation of enzymes, proteins, and nucleic acids.

Applications of microwave heating

Applications of microwave heating are found for most of the heat treatment operations in the food-processing industries. Microwave heating offers the opportunity of shortening the time required in conventional heat treatments to achieve the desired food-processing temperature.  Microwave pasteurization and sterilization promise fast heat processing.