Microwave energy is a kind of electromagnetic energy with frequency between 300 MHz and 300 GHz. As a heating resource, microwave energy is dramatically applied in the food industry. There are six main applications microwave thermal effect, microwave non-thermal effect, microwave extraction, microwave drying, microwave sterilization and microwave puffing

1.Principle and Features of Microwave Heating

1.1 Principle of Microwave Heating

It is widely acknowledged that material consist of  the polar and non-polar properties of the molecules. Random polar molecules will follow the direction of electric field under the  electromagnetic energy. However, under microwave energy, the frequency constantly changes billions times/seconds. It cause molecules’ friction and fiercely movement which generate heating effect so electric energy is directly and completely transformed to medium heat. microwave energy absorbed is expressed by

P = 2 π f v² E0 Er tanð

Where P = the power density of the material = energy absorbed (W/m³)

f=frequency(Hz) （Commercial industry 915MHz or 2450MHz）
v=electricfield(V/m) 
E0=dielectric permissivity of free space (8.85 x 10-12 F/m) 
Er=dielectric constant of thematerial 
tanð = loss tangent

1.2  Features of Microwave Heating

1.2.1 Heating Fast- Regular heating process starts external firstly, microwave heating begins in the internal material. electromagnetic energy directly work on the dielectric molecule in order to transform to heat, meanwhile the heated material do not need heat conduction. So the material could be heated both inside and outside in a short time.

1.2.2 Uniform Heating- External heating method only rises up temperature if they are willing to speed up heating time. There will be a temperatures grade scenario which cause outside is burnt and inside is still unmature. No matter what kind shape of material, microwave energy could averagely infiltrate and yield heating in order to significantly improve features.

1.2.3 Choosing Heating-Different character of material has the unique absorbing (losing) feature for microwave energy namely microwaves have the choosing feature, it benefits for drying process. As water molecule has the highest energy absorbing(losing), so higher water of material contain, the more microwave energy will be utilized. Therefore, the whole part will obtain the same drying result especially for irregular shape material

1.2.4 High Efficient- polythene and other material barely absorb microwave energy, and metal material reflect microwave energy, so those material will not be heated by microwave energy. Hence the heating chamber and air will not be heated, only the resource is processed by microwave energy. It has a high efficient character

1.2.5 Clean, Keep Nutrition and Flavor-Microwave heating energy is capable of sterilizing bacteria under low temperature. It maximum keep food nutrition and minimize discoloration ,distaste and appearance.

2.Application in Food Industry

2.1. Microwave Extraction

2.1.1 Principle of Microwave Extraction- Using microwave radiation penetrating dielectric constant by high frequency electromagnetic wave, to arrive the vascular bundle and Gland cell system. The temperature of internal cell rise rapidly due to absorb the microwave energy, so internal pressure force cell wall pierced. Operator could obtain the extraction under cool temperature which compares to traditional extraction method. Through further filtration and separation,  we could gain the pure extraction material

2.1.2 Using traditional extraction method analyzing food is time waste, low efficient and inaccurate. Microwave extraction is fast, accurate, Solvent-free and save samples. For example, we take cheese, Italian sausage and cauli-flower as samples to extract amino-acid. The result shows: extraction temperature is between 40 ℃ and 50 ℃， 3 times  radiation with 2 minutes radiating time. Microwave extraction is more 66% time saving and 10% efficient over conventional method.

2.2 Microwave measure trace element-(1).”internal heating” has a faster heating time, uniform heating effect, immediate result and no temperature grade. (2)Especially for insoluble material, old method may take few days to dissolve sample, but microwave energy only take few minutes or hours.(3)we only need 5ml~10ml to dissolve sample by microwave energy.(4) Complete reduce manual operation and hazardous emissions.

2.3 Microwave energy has a choosing drying method for water especially for food, pulp material and paper etc. There are many advantages using microwave dryer like fast, efficient, uniform heat, energy saving,  easy operation and control, environmentally-friendly, maximum keep food nutrition and appearance.

Base on those theories, MAX design and manufacture new generation microwave system for industry