Milk disinfection and preservation technology

Milk is a paradise for microbial activity. According to the test, the freshly squeezed milk was treated without any treatment at room temperature. After 12 hours, the microbiological content per milliliter of milk reached 114,000, and it increased to 1.3 million per milliliter by 24 hours. This is why milk is prone to corruption. Therefore, the disinfection and preservation of milk is very important. I. Disinfection of milk In the production process, the milk that has just been squeezed out is generally put into a milk tank first and then cooled rapidly to suppress the proliferation of microorganisms and prolong the duration of antibacterial activity of the milk. Cooled milk needs to be sent to the factory for processing. That is, through filtration, purification, cooling, homogenization, sterilization and packaging, etc., it becomes a daily drinking disinfectant milk. Sterilization is an important process for producing disinfected milk. The pasteurization method was generally adopted (invented by the German microbiologist Louis Pakde in the 1850s, so it was named after it). This method is divided into two kinds of low temperature and high temperature disinfection method. The low-temperature sterilization method is to put milk into a special pasteurizer, heat the milk to 62°C-65°C and maintain it for 30 minutes; the high temperature sterilization method is heated to 73.8°C-76.6°C for 1-10 minutes, or 82.2°C, no more than 5 minutes. Then quickly cool to 10°C. The purpose of cooling is to prevent the propagation of residual spores and maintain the quality of the milk. In addition, the use of soil method can also achieve the purpose of disinfection. That is, after prospering, the milk fat film is quickly formed on the surface of the milk (the milk does not overflow), just like a cloth covering the waves. Calculated from the formation of fat film, cook for 15 minutes, you can achieve the effect of pasteurization. The disinfection of milk must strictly control the temperature and time. Otherwise, it can not reach the purpose of disinfection, but also destroyed the nutrients of milk. This is because: First, boiling at high temperature for a long time causes the protein in milk to change from a sol state to a gel state, which causes a large amount of coagulation and precipitation of proteins. Second, calcium in fresh milk is electrostatically combined with casein to form The human body can digest the absorbed casein calcium. Compared with the sterilized milk, the boiled milk for a long time has about 20% less casein. The calcium becomes more difficult to be digested and absorbed by the human body. The third is boiled for a long time. Lactose decomposes and decomposes, and the nutritional value is low. Fourth, it destroys many vitamins including vitamin A. Therefore, sterilized milk is in principle consumed directly and it is no longer necessary to boil it. If you need to warm up, just heat the bagged milk in hot water at 50°C to 60°C for a while. Second, disinfecting milk to disinfect and disinfect milk is not easy to keep at room temperature. Milk is scared of sunlight. Under sunlight, vitamin A, carotene, vitamin B1, and vitamin B12 contained in milk are damaged, so it is best to avoid light and refrigeration. According to experiments, the milk is cooled to 13°C and can be stored for 12 hours. Therefore, the temporarily sterilized milk that is not used for drinking can be placed in a refrigerator or a freezer but not in the freezer. Once milk is frozen and reheated, the separation of fat and protein occurs, and solidification and precipitation occur. At this point, the fats and fats float, the milk taste changes, and the nutritional value is reduced. If you buy the milk from a self-employed person, it is best to drink it after boiling and disinfect it. It should not be kept. If you want to save, you can use a small mouth container, sealed and stored, but the time should not be too long.

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