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.

2

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

3

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

companies 4

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.

5

Microwave sterilized salmon and rice

Conventionally processed (canned)

salmon 6

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.

7

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.

8

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

9

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.

10

Typical Microwave Heating Equipment

11

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

12

Multimode Applicators

13

14

15

Horn Applicator

Used to beam the energy into a conveyor tunnel.

The energy from the magnetron is split equally four ways.

16

Disadvantages Of Microwave For Cooking Food

Cold Spots ?

17

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.

18

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.

19

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.

20

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.

21

References

http://www.wsu.edu/ Microwave heating by By A.C. Metaxas

22