Are all the milk in the freezer really good?

China Food Safety News recently, the National Health and Health Commission and others issued the "New Coronavirus Infected Pneumonia Prevention Dietary Guidelines", the guidance clearly stated that "try to drink 300 grams of milk or dairy products every day." It is understood that this is because milk protein contains unique components that regulate immune function, such as immunoglobulin and lactoferrin. But what consumers often do not know is that the different sterilization processes of milk, the content of active nutrients in milk will also be very different.
How to choose fresh milk? Small choice, university asks
Is the real milk in the freezer? Really good fresh milk, nutrition is fresh enough!
Today, there are a lot of milksource dairy products on the freezer of supermarkets. In addition to normal temperature milk, pasteurized milk and milksource dairy high temperature sterilized milk are currently on the market. Many consumers said that, in addition to normal temperature milk with a shelf life of up to 6 months, the milk in supermarket refrigerators is pasteurized milk with a shelf life of 7 days; some is high temperature sterilized milk with a shelf life of 15 days. But the price is almost the same, the nutritional content is also similar, and some normal temperature milk is also sold in the freezer, which has misled consumers. Consumers do not know what is the difference between them and how to choose.
Normally, the normal temperature milk in the supermarket is marked as sterilized milk. It is produced according to the GB25190 standard for sterilized milk. Without mentioning nutrition, its unit price is much lower than that of refrigerated milk, and the shelf life is up to 6 months. For refrigerated milk, some are marked with pasteurized milk at 75 degrees Celsius; some are pasteurized but not marked with sterilization temperature; some are simply high-temperature sterilized milk, and the production standards involved in different processes are also different, such as high-temperature sterilization Milk is produced in accordance with the standards of their respective companies, and pasteurized milk is produced in accordance with GB19645 pasteurized milk national standard. What is the difference between these three sterilization methods?
Look at the temperature, whether it is fresh or not, the protein activity should be protected.
Pasteurized milk is generally below 85 degrees Celsius, and the sterilization time is about 15 seconds; while high-temperature sterilization milk, the sterilization temperature is usually between 110-130 degrees Celsius, and the sterilization time lasts for a few seconds. Compared with pasteurized milk, high temperature sterilized milk has a relatively high sterilization temperature, and also kills active protein substances such as lactoferrin, lactoperoxidase, and immunoglobulin. However, since there is currently no requirement to indicate the content of these active protein substances on the packaging, consumers cannot see the difference.
Gu Jiasheng, deputy director of the National Dairy Technology Innovation Alliance, said: "In terms of lactoferrin, it is very sensitive to temperature, and it is destroyed when it kills bacteria. It is generally fixed for 15 seconds and the (sterilization) temperature is 75 degrees. At 72 degrees, the effect of lactoferrin, the reduction is not more than 20%, the temperature is 85 degrees higher, 60% is gone, there is probably 40%, and basically 90 degrees or more is not found. "
Among the current national food safety standards, only sterilized milk and pasteurized milk standards. General sterilized milk refers to the sterilization temperature above 135 degrees Celsius, to maintain a short time sterilization. The national standard for pasteurized milk is defined as a liquid product made from raw cow and goat milk as raw materials and subjected to pasteurization and other processes. Because there are no requirements for active protein substances, and no definition of pasteurization temperature and time, some companies even use sterilized milk at about 120 degrees, which is marked as pasteurized milk sales. Since there is no national standard for high-temperature sterilized milk, everything is up to the enterprise.
Dr. Gui Min, State Key Laboratory of Dairy Biotechnology, said: "Pasteurized milk without a temperature indication does not contain active lactoferrin. UHT includes room temperature milk stored at room temperature, which is free of lactoferrin. There is also a kind of refrigerated milk that is now sold in a cold air cabinet. It can not be classified as pasteurized milk by high-temperature sterilization process. This kind of milk does not contain lactoferrin. The content of immunoglobulin in pasteurized milk is very high Yes, above 100 mg per liter, there is some in pasteurized milk, not in high-temperature sterilized milk. "
It can be seen that milk that is also sold in supermarket freezers has different sterilization processes, and the auxiliary effect on human immunity is completely different. Active protein substances such as lactoferrin, lactoperoxidase, immunoglobulin, which are extremely sensitive to temperature in milk, are completely destroyed in high-temperature sterilized milk and high-temperature sterilized milk, and only the sterilization temperature is controlled below 85 ℃ The ability to retain the fresh nutrition of milk is called real pasteurized fresh milk.