Freezing techniques include freezing concentrated juice, quick-frozen vegetables, quick-baked baked goods, quick-frozen technology, pre-made frozen foods, etc., the application of the principle of glass transition in the processing and storage of frozen foods; genetically engineered food materials, especially Special flavor and color of vegetables. Further, the new variety obtained is combined with a cryopreservation system to prevent quality changes during the freezing process.
　　
Refrigeration technology and equipment in the food processing industry, pre-treatment, pre-cooling and quick-freezing of raw materials belong to the cold processing of food, which has a great impact on the final quality of food. This part is also a necessary process for frozen food factories, cooling meat and chilling. The freezing process of meat and acid-free, quick-frozen vegetables. China's refrigeration technology is growing, and frozen food is also favored by consumers. A better understanding of the origin of food sensory traits from a material science perspective.
　　
Progress and development prospects of cryopreservation equipment
　　
Application of the principle of glass transition in the processing and storage of frozen foods
　　
As early as 1948, Schmidt and Marles pointed out: "Low-molecular weight-like substances like glass are an important class of solidified asphalt, natural resins, hard candy, etc.." In the mid-1960s, the United Kingdom Scientists White and Cakebread first proposed the idea of ​​food glass transition in candy manufacturing. They recognize the importance of glass state, glass transition temperature, and glass transition temperature relative to the storage temperature of many liquid foods and the extreme importance of water as a food glass plasticizer. In 1985, the Royal Society of Chemistry held a seminar on water activity in Cambridge. The water activity was discussed extensively and carefully as a measure of food storage stability [3]. More than 50 scientists from different countries participated. After the meeting, after four days of academic exchanges and contends, he questioned the various defects of the effect of water activity on the storage stability and living viability of food, and put forward the theory of “food polymer scienceâ€. Although the number of people attending the meeting was small, the meeting was a milestone in the establishment of the theory of food polymers.
　　
Microwave continuous thawing of frozen food
　　
With the improvement of refrigeration technology, the need for efficient thawing technology to speed up the thawing process and to avoid affecting the quality of the final product has become the focus of the development of new thawing technology. To date, the thawing of frozen foods has a natural thawing method using flowing water and a heat source thawing method using high temperature air and steam. The treatment of frozen foods by such methods has a problem of oxidation and bacterial growth due to the slow heat transfer and the appearance of the food when the thawing temperature is reached. An appropriate solution to the above problem is to develop an "internal" thawing method that maintains a low temperature, and the microwave heating method is attractive in this respect.
　　
Because the penetration of microwaves is low, it is necessary to irradiate the frozen foods from the upper and lower directions in order to reach the thawing temperature. This direct-emitting structure can easily damage the magnetron if the transmitter is placed on both sides of the conveyor belt.