With the continuous development of society and science and technology, people put forward higher requirements for food processing, microwave technology as an advanced technology, with fast heating speed, good uniformity, high thermal effect, environmental protection and energy saving and easy to control and other aspects of the advantages of the food processing in a very good application.

Therefore, the research on the application of microwave technology in food processing is of great significance, which can play a role in promoting the application of microwave technology in food processing, and also can give full play to the use of microwave technology in food processing, improve the technological level of food processing, and provide people with more high-quality food. This paper starts from the principle of microwave technology, from microwave technology in food sterilization, food aging, food drying, as well as miscellaneous grain hulling these specific applications in food processing to explore.

The principle of microwave technology

The composition of the media materials, including polar molecules and non-polar molecules in two parts, the beginning of the polar molecules in the state of thermal movement, under the action of the microwave electromagnetic field, the state of polar molecules according to the direction of the electromagnetic field alternating direction and produce changes in the arrangement of the orientation.

From a microscopic point of view, the energy of the alternating electromagnetic field is converted into thermal energy within the medium, from a macroscopic point of view, the temperature of the medium appears to rise, which is the principle of microwave heating.
It can be seen, the essence of microwave heating is the medium material loss of its own electromagnetic field energy to generate heat to other substances for heating.

For metal materials, the electromagnetic field not only can not penetrate into the internal, but will be reflected by the metal material, therefore, metal materials do not have the role of microwave absorption.

In many media, water has the best absorption effect on microwaves, therefore, as long as the material containing water will certainly be able to absorb microwaves. Part of the non-polar molecular structure of the medium can also absorb microwaves to varying degrees.

Application in food processing

2.1 Food Sterilization
The application of microwave technology in food sterilization is a complex process of interaction between microwaves and living organisms, in which the living organisms will absorb the microwaves radiated from the microwaves and then produce comprehensive biological effects.

The basic principle has two aspects, one is thermal effect and the other is non-thermal effect. When the application of microwave sterilization of food, food as a whole can be rapidly warmed up, sterilization time is very short, can maximize the retention of food color, aroma, taste and nutrients.

Microwave heating with conventional heat sterilization together, can let them complement each other, and play their respective advantages, both conventional heat sterilization time to be effectively shortened, but also allows some moisture content is not uniform, the composition of complex food in the microwave sterilization can also be uniformly heated.

2.2 Food aging
Traditional methods of food aging takes a long time, such as the natural aging of wine often takes several years or even decades. Microwave technology is currently the most widely used in the aging process, the most reliable performance and the most obvious effect of a technology that can effectively shorten the time needed to promote aging.

Microwave aging consists of two principles, one is the chemical reaction of microwave on wine, and the other is the thermal effect of microwave on wine.

The main chemical composition of wine is water and ethanol, of which the ethanol molecule is unstable, wine spicy flavor is produced by ethanol; to take microwave technology to promote the ageing of wine, ethanol molecules and water molecules in the wine will be rearranged in the microwave field under the action of the water molecules will be more neatly arranged to reduce the ethanol molecules of the activity of the wine, the pungent flavor will be reduced, and the taste has become more mellow.

2.3 Food drying
When the microwave technology used in food drying, moisture from the inner layer to the outer layer of the process of dissemination is very rapid, compared with the traditional drying methods, drying speed to be much faster, especially for the material drying of the subsequent links, this advantage is more obvious.

Microwave technology in food drying is widely used, mainly including general food microwave drying, food microwave freeze drying and food microwave vacuum drying. Microwave drying of food has many advantages, such as fast drying speed, uniform product heating, good drying quality, energy saving and hygiene.

However, microwave drying has the disadvantages of large investment in equipment and high power consumption, and its economic benefits are not ideal for materials with high water content.

Therefore, in practical applications, microwave heating and drying often with hot air drying and near infrared drying and other drying technologies used in conjunction with microwave drying is usually used in the food drying of the subsequent links.

2.4 Grain hulling
Grain hulling is one of the more common food processing links, more everywhere in China, it is a rather troublesome work, small grain crops have different physical properties, so the hulling of its process is also different.

For easy to shell the small particles of crops, only direct shelling can be dealt with, and for some crops that are not easy to shell, need a special treatment to shell.

At this point, microwave technology can show its advantages, its application in the shelling of crops that are not easy to shell the shelling process, will make the original complexity and trouble of the shelling work has become simple and convenient.

The principle of microwave dehulling is that the moisture in the shell kernel of the grain will be under the action of microwave alternating electromagnetic field, resulting in a large number of thermal energy aggregation, and then these energies will be spread to the outside at a very high speed, the kernel will be shrinking due to loss of water, and the degree of adhesion to the shell is greatly reduced to complete the kernel-shell separation of the dehulling process.

Conclusion

Microwave technology in food processing has achieved certain results, such as in this paper describes the food sterilization, food aging, food drying, food processing in the hulling, microwave technology have played a very good advantage.
Research on the specific application of microwave technology in food processing, to help better understand and master microwave technology, microwave technology in food processing to give full play to the role of food processing, so that food processing is more simple, convenient, fast, so that the nutrients of food can be retained, food taste better and richer, and ultimately achieve the purpose of improving the level of food processing.