Ultra high temperature processing milk
Milk is a highly perishable food, so in order to make it storage and distribution for consumption without deterioration, and not to pose a health threat to the growth of pathogens, the Milk Production Line heats the milk. In many parts of the world, the most common type of heat treatment is pasteurization, which is carried out at at least 72 ° C for 15 seconds. This is the minimum heat treatment required to destroy most pathogenic microorganisms and also destroys most spoilage microorganisms. However, after pasteurization and packaging, a small amount of bacteria still exists and can grow during storage. This growth is slow at low temperatures, so pasteurized milk is always kept cold. Even in cold storage, pasteurized milk can only be stored for about two weeks.
One way to extend the shelf life of milk is to heat the milk to a temperature sufficient to destroy almost all microorganisms and then store it in a sealed container without contamination by bacteria. There are two ways to do this: in-container sterilization and ultra-high temperature (UHT) treatment. Both produce "commercially sterile" products, which means that the milk does not contain microorganisms that can grow under normal storage conditions, in which case the normal storage conditions are room temperature 2,3.
In-tank sterilization using canned technology is a batch operation involving heating the final milk container at 110 - 120 ° C for 10-20 minutes in an autoclave. In contrast, ultra high temperature processing involves heating the milk in a continuous flow system at about 140 ° C for a very short period of time - about 5 seconds.
Although the two methods have the same microbial action, their chemical effects on milk components are quite different. Sterilized milk in containers usually has a noticeable ripeness and a slightly brownish color. On the other hand, the milk of the UHT Milk Machine is much less cooked, and the brown color (if any) is rare. The difference in product quality between these two sterilized milks is the main driver for the development of ultra-high temperature processing to produce shelf-stable products. However, the main driver of commercialization and widespread adoption is the development of aseptic packaging, through which sterilized milk is packaged as aseptically packaged and sealed.