Basic introduction Chinese name: Frozen food includes: chilled food and frozen food features: easy to preserve and applicable: production, transportation and storage of perishable food; Generalization, concept classification, invention, application of new freezing technology in food, film wrapping freezing method, ultrasonic freezing technology, high-pressure freezing technology, ice nucleation active bacteria freezing technology, biological frozen protein technology, instant freezing system, food decompression freezing, influencing factors, transportation industry, industry standards and specifications, equipment quality, industrial transformation, generalizing concept classification, cooling food: it is not necessary to freeze, but to reduce the temperature of food to near freezing point, and in the process of freezing. Frozen food: it is food that is preserved at a temperature below the freezing point after freezing. Cold food and frozen food are collectively called frozen food, which can be divided into five categories according to raw materials and consumption forms: fruits and vegetables, aquatic products, meat, poultry and eggs, rice and flour products and instant foods. Francis Bacon, the writer and philosopher who invented Britain17th century, tried to put snow into a chicken to freeze it, but he was caught cold and soon fell ill. Even before Bacon's unfortunate experiment, people knew that extreme cold could prevent eating meat from "going bad". This made the rich landlords set up icehouse where they could keep food in their farms. None of these early attempts to freeze food caught the crux of the problem. It is not so much the degree of freezing as the speed of freezing, which is the key to freezing meat. Probably the first person to realize this was the American inventor Clarence Boziey. It was not until 1950s and 1960s, when household freezers became increasingly popular, that frozen foods began to be sold in large quantities. Soon after, the famous red, white and blue packaging of Bozeyi existed in shops in many parts of the world and became a familiar landscape. A few years after World War I, Boziey made a survey of wild plants while traveling in Labrador Peninsula, Canada. He noticed that the weather was so cold that he caught a fish and it froze hard for a while. He wondered whether this was the key to food preservation. Unlike Bacon, Boziey lived in the age of freezers. 1923 After returning home, he used the freezer to do experiments in his kitchen. Then, Boziey tried to freeze different types of edible meat in a large refrigeration plant. Boziey finally found that the fastest way to freeze food is to press the meat tightly between two frozen metal plates. By the 1930s, he was ready to start selling frozen food produced by his Springfield, Massachusetts factory. For Boziey, frozen food quickly became a big business. Even before he invented the efficient double-plate freezing process, his company reached the freezing capacity of 500 tons of fruits and vegetables a year. The application of new freezing technology in food is encapsulated freezing method. CPF method has many advantages: the membrane formed when food is frozen can inhibit the expansion and deformation of food; Limit the cooling speed, the ice crystals formed are fine, and will not produce large ice crystals; Prevent cell destruction, and the product can be naturally thawed and eaten; Food tissue tastes good and has no aging phenomenon. Ultrasonic freezing technology is an Ulrasonic Frozen Technolo-gy-gy. UFT is to improve the food freezing process by using ultrasonic wave. Its advantages are that ultrasound can strengthen the heat transfer in the freezing process, promote the ice crystallization in the food freezing process and improve the quality of frozen food. Various effects caused by ultrasound can make the boundary layer thinner, increase the contact area and weaken the heat transfer retardation, which is beneficial to improve the heat transfer rate. The research on strengthening the heat transfer process shows that ultrasound can promote the nucleation of ice crystals and inhibit crystal growth. High Pressure Freezing technology (high pressure freezing), HPF uses the change of pressure to control the phase change behavior of water in food. Under high pressure (200 ~400MPa), the food is cooled to a certain temperature, at which time the water is still not frozen, and then the pressure is quickly released to form ice crystals with small and uniform particle size inside the food. Moreover, the volume of the ice crystals will not expand, which can reduce the damage to the food tissue and obtain freezing that can maintain the original food quality. Ice nucleation active bacteria freezing technology Ice nucleation active bacteria freezing technology, the research field of biological ice nucleation is constantly expanding and deepening, and it has developed from ice nucleation bacteria to ice nucleation fungi. At present, 4 genera 1 1 species of ice nucleation fungi have been reported, except for 3 lichen fungi, the other 8 species belong to Fusarium. The advantages of using ice nucleation bacteria to assist freezing are: it can improve the freezing point of water in food materials, shorten the freezing time and save energy; Promote the growth of ice crystals, form larger ice crystals, reduce the cost of freezing operation, and make the subsequent separation of ice products and concentrated materials easy; The entrainment loss of food materials on ice crystals is reduced, the purity of ice crystals is improved, and the solid loss is reduced. The freezing technology of adding ice nucleation bacteria to food materials to be frozen has been applied in food freeze-drying and juice freeze-concentration. Biological frozen protein technology Biological frozen protein technology (BFPT) is to directly add extracellular biological frozen protein to food materials. The activity of bacterial extracellular frozen protein is higher than that of the whole ice nucleation cell, and the ordered fibrous flake ice crystals can be obtained, which effectively improves the texture of frozen food and improves the freezing efficiency. Instant freezing system Instant freezing system (Cellular freezing system), CAS freezing system is a combination of dynamic magnetic field and static magnetic field, which releases tiny energy from the wall to make the water molecules in food in a fine and homogeneous state, and then immediately cools the food from supercooled state to below-23 C and freezes it. Because the expansion of frozen crystals is restrained to the maximum extent, the cell tissue of food is not destroyed, and after thawing, the color, fragrance, taste and freshness of food can be restored, and there is no loss of juice, and the taste and water retention are well maintained. VacuumFrozen food vacuum frozen food vacuum frozen preservation is composed of vacuum cooling, low temperature preservation and gas storage. It has the characteristics of low temperature and low oxygen, which inhibits the growth and breathing of microorganisms and reduces the influence (damage) of oxygen and carbon dioxide on food. Therefore, vacuum freezing preservation not only has the advantages of rapid freezing, prolonged storage time and improved storage quality, but also prolongs the shelf life of food. Influencing Factors The number of refrigerated and insulated vehicles in China has increased from about 3,500 vehicles in 1980 to about 30,000 vehicles in 2000. At present, there are more than 100 varieties of refrigerated and insulated vehicles produced in China. However, compared with developed countries, there is still a big gap. First, there are too many factories, scattered investment, repeated construction and repeated introduction in the refrigeration and heat preservation automobile industry in China, which is "scattered, chaotic and poor"; Second, there are few refrigerated and insulated vehicles in China. At present, there are only about 30,000 insulated vehicles in China, while there are more than 200,000 in the United States and100000 in Japan. Third, the proportion of refrigerated and insulated vehicles in freight cars is only about 0.3% in China, 0.8% ~1%in the United States, 2.5% ~ 2.8% in Britain and 2% ~ 3% in developed countries such as Germany. China's refrigerated transport rate (that is, the proportion of perishable goods transported by refrigerated transport) is about10% ~ 20%, and Europe, America, Japan and other countries all reach 80% ~ 90%. The proportion of refrigerated transportation in China (that is, the ratio of the volume of perishable goods transported by refrigerated vehicles to that transported by railway) is about 20%, and that in European countries is 60% ~ 80%; Fourth, although the variety and technical level of refrigerated vehicles in China have been greatly improved, for example, K value (K value: a characteristic of microbial heat resistance, changes with the variety of microorganisms and sterilization temperature. At the same temperature, the smaller K, the more heat-resistant microorganisms are. The index is close to the international advanced level, but compared with the developed countries, the varieties can't meet the market demand. For example, in the 1970s, there were more than 350 kinds in Japan, especially the carriage structure and the forms of carriage doors, so there is a great choice. The product level of some enterprises that have imported technology and equipment in China is close to the international advanced level, but there is still a gap in design ability, equipment manufacturing ability and technical service ability. Industry Standards and Norms According to the current situation, under the condition of market economy, commercial system, light industry system, foreign trade system and aquatic products system are all producing frozen food in their own way, and there is no unified industry standard and norm to follow, and the management is in a disorderly state, resulting in uneven quality of frozen food. In addition, most frozen food production enterprises in China use the original cold storage, freezers, etc. to produce frozen food, and there is no continuous rapid freezing equipment, and there is no unified product quality standard and hygiene standard, resulting in the slow freezing production flooding the market, reducing the quality of frozen food and damaging the reputation of frozen food. Although there is a certain basis for the production of domestic quick-freezing machines, compared with similar products abroad, there are some problems such as bulky, heavy, poor low-temperature performance and high energy consumption. The gap between the transmission parts produced by some quick-frozen parts manufacturers and similar products abroad is mainly due to rough appearance, poor precision and unstable performance. For a stainless steel strip with a circumference exceeding 10 meter, due to the accumulated error, the metal steel strip is prone to chain belt jumping and belt breaking in low temperature environment, resulting in the loss of production stop for users. The length of spiral belt is generally more than 100 meters, and the quality of domestic belt is unstable, which is prone to belt squeezing and disconnection. At present, the frozen food enterprises are small in scale, weak in strength and low in economic benefits. At present, there are about 1000 frozen food production enterprises in China, and "the quantity is stable at more than 1,000 tons", and most of them are about 100 tons. Among these enterprises, a considerable number of frozen foods are actually just a branch factory or a workshop of slaughterhouses, canneries, cold drinks factories and other factories, and this enterprise has great scale benefits. At present, the frozen food enterprises with import and export rights have good economies of scale. However, it should be noted that the international market is unpredictable and the competition is fierce. Foreign companies are particularly interested in China's market. After China's entry into WTO, China's market will face all-round opening, from unilateral self-opening to two-way opening among WTO members, and there will be no existing protective measures. Domestic preferential policies and other factors, foreign enterprises will fully challenge China enterprises, product standardization and product quality supervision and inspection institutions can only fully integrate with international standards. Industrial Transformation In China, the related industries supporting the quick-frozen industry, such as flour processing industry, meat and poultry breeding and slaughtering, and cold chain transportation, are far behind the development of the quick-frozen food industry. Affected by production technology, transportation and other conditions, the quality of quick-frozen food products is still slightly insufficient. Constrained by the industrial chain, the so-called "Staphylococcus aureus" can meet the standards in the production process, but it is difficult to guarantee in the transportation, circulation and terminal. The cold chain, cold storage and freezer of retail terminal in the transportation process may not meet the standards. On the one hand, it is fierce competition and harsh competitive environment, on the other hand, it is a huge market space. In the international market, more than 60% of frozen food is used in catering industry, while the proportion in China is less than 5%. The huge market will trigger the rise of the quick-frozen food business market and provide new business opportunities and space for the development of the quick-frozen food industry. 20 12 10, China produced 363,000 tons of quick-frozen rice flour food, an increase of 8.36% over the same period of last year; 20 12 years 1- 10, the national production of quick-frozen rice flour food was 3142,000 tons, an increase of 16.95% over the same period last year. 20 121-June, among the main foods related to sugar consumption in China, the cumulative output growth rate of candy, canned food and quick-frozen rice flour food was lower than that of the same period of last year. Compared with May, the growth rate of candy and quick-frozen food production showed a significant upward trend compared with the growth rate of last month. 20 12 years 10, the output of wheat flour in China was11242,000 tons, an increase of 2.99% over the same period of last year and an increase of 3.17% over the previous month. 1- 10, the cumulative output of wheat flour in China reached10/199,000 tons, an increase of 8.5 1% over the same period last year. 20 12 10, the flour output of enterprises above designated size increased year-on-year and month-on-month. 10 The flour output of enterprises above designated size11242,000 tons, calculated according to historical data, increased by 2.99 year-on-year and 3.2% month-on-month; Cumulative output101120,000 tons, up 8.5 1% year-on-year. In Japan, 70% of frozen foods are used for fast food and group meals, while most of frozen foods in China are currently supplied to supermarkets for retail. At present, the sales revenue of quick-frozen industry is less than1000 billion yuan, and the sales revenue of similar catering industry is nearly 3 trillion yuan, which is very large compared with the sales of catering industry and the same industry in developed countries.