Microwave Food Processing
Nalaka NugapolaAnimal ScienceUva Wellassa University of Sri Lanka
How Does Microwave Heat Foods?
Microwaves interact with polar water molecules and charged ions.
The friction resulting from molecule alignment and migration of charged ions in rapidly alternating electromagnetic field generates heat within foods.
Federal Communication Commission (FCC) allocates 915 MHz and 2450 MHz bands for microwave heating applications.
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Current Industrial Applications
Microwave ovens operating at 2450 MHz
2450 and 915 MHz systems between 10 to 200 kW heating capacities are used in the food industry,• Precooking bacons• Tempering deep frozen meats• Meat patties• Precooking many other foods products
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Advantages Of Microwave Sterilization
Reduction in the thermal processing time Fresh-like taste and texture, and
improves visual appeal
Increases retention of nutrients Better energy usage Post packaging processing Great opportunities for innovative food
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Can Microwave Sterilization Be Used For Processing All Foods?
Conventional thermal treatments.
The shorter time and more uniform volumetric heating.
Salmon fillets, macaroni and cheese, massed potato and beef in gravy cab.
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Microwave sterilized salmon and rice
Conventionally processed (canned)
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Can Microwave Sterilization Be Used For Processing All Foods?
Advantages -product properties, state, shape and thickness, processing system design.
Compared with conventional food processing, microwave sterilization could potentially improve sensory, appearance and nutritional value.
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Shelf Life Of Microwave Processed Products
Microwave sterilization can achieve the same reduction of bacterial population as conventional retorting.
Packaging materials - Plastic trays or pouches.
Normal shelf life is 2-3 years or longer.
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How Are Microwave Processed Foods Stored?
Microwave sterilized foods can be stored at ambient temperatures and re-heated in the common household microwave prior to consumption.
These products do not require refrigeration
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How Economical Is Microwave Sterilization Processing?
Ability to heat solid, semi-solid and meal combination food products
More rapid heating and preservation of sensory and nutritional quality
Possibility of ascetic packaging High throughout of processed foods Possibility of incorporation of microwave
processing equipment in the existing processing lines.
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Typical Microwave Heating Equipment
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Microwave Applicators
The most common form of an applicator (>50%)-multimode type.
In principle, it is an extension of the domestic microwave oven but built for large scale material processing
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Multimode Applicators
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Horn Applicator
Used to beam the energy into a conveyor tunnel.
The energy from the magnetron is split equally four ways.
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Disadvantages Of Microwave For Cooking Food
Cold Spots ?
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Industrial Applications
Food tempering
Meat, fish, fruit, butter and other foodstuffs can be tempered for cold store temperature(-3ºC)
For ease of further processing such as grinding the meat in the production of burgers or blending and portioning butter packs.
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Industrial Applications
Heating and cooking
Many foodstuffs have been cooked by microwaves for various stages of processing.
• Bacon cooking in a combination system,• Meat coagulation to upgrade scrap and
doughnut • Cooking for frying.
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Industrial Applications
Pasteurisation and sterilisation
Food products, such as bread, precooked foods and animal feedstuffs have been processed using microwaves for pasteurisation or sterilisation or simply to improve their digestibility.
Food pasteurisation of sealed packs under pressure can be effected by microwave energy.
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Conclusions
Microwave heating has been established in a number of industrial sectors.• Tempering• Blanching• Sterilising• Cooking• Puffing
Vacuum drying offers the biggest opportunity for microwave processing.
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References
http://www.wsu.edu/ Microwave heating by By A.C. Metaxas
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