Food sterilization can extend the shelf life and freshness period of food, and can also eliminate various bacteria present in food, such as Escherichia coli, Bacterium cereus, Bacillus megaspermum, Shigella dysenteriae, Salmonella typhi, Diplococcus meningitis, and Staphylococcus aureus. Cocci and other bacteria can be killed to ensure the safety of food consumption. In terms of food sterilization, currently commonly used technical means generally include: ultraviolet sterilization, high temperature and high pressure sterilization, ozone sterilization, microwave sterilization, steam sterilization and radiation sterilization, etc.
1. Ultra-high pressure sterilization process
advantage:
This ultra-high pressure processed product can fully maintain the original color, aroma, taste and nutritional content of food raw materials, thereby extending the shelf life of the product. The color, flavor and nutrition of ultra-high-pressure processed juice are almost the same as those of fresh juice processed by pressure.
shortcoming:
Due to the high pressure of the ultra-high pressure sterilization process, pressure-sensitive components in food will be damaged to varying degrees. Its excessive pressure increases energy consumption and imposes high requirements on equipment; the initial investment cost of ultra-high pressure equipment is relatively high, and general food factories are not conducive to industrial promotion;
2. Pasteurization process
principle:
Pasteurization actually takes advantage of the fact that pathogens are not very heat-resistant and uses appropriate temperature and holding time to kill them all. However, after pasteurization, a small number of harmless or beneficial, relatively heat-resistant bacteria or bacterial spores are still retained. Therefore, pasteurized milk should be stored at a temperature of about 4°C, and generally can only be stored for 3 to 12 days. .
Pasteurization is mainly used for the sterilization of milk, wine, beer, and juice.
advantage:
Heating food within a specified time to kill microbial nutrients is a method that can achieve the purpose of disinfection without damaging food quality.
shortcoming:
Because the temperature reached by pasteurization is low, the degree of sterilization cannot be achieved.
3. Ultra-high temperature instant sterilization process
principle:
Ultra-high temperature sterilization is referred to as UHT sterilization. The general heating temperature is 125 ~ 150 ℃, the heating time is 2 ~ 8 s, and the sterilization process in which the heated product meets the commercial sterility requirements is called UHT sterilization.
Ultra-high temperature sterilization is widely used in home appliances such as bottle sterilizers, dishwashers, sterilizing cupboards, washing machines (with sterilization function), steam mops, etc. For example, some washing machines provide high-temperature washing functions to achieve the purpose of sterilization.
advantage:
The short sterilization time allows the product to have a longer shelf life, which can generally reach more than 30 days.
shortcoming:
Strong heat treatment will have certain adverse effects on the appearance, taste and nutritional value of food.
4. Ultraviolet sterilization process
principle:
Utilizing the radiation effect of ultraviolet rays, lamps are used to directly irradiate bacteria to cause photochemical reactions, thereby inhibiting the replication of DNA and destroying bacteria. In addition, ozone (O3) produced in the air under ultraviolet irradiation also has a certain bactericidal effect.
advantage:
Now more and more home appliances are beginning to be used. For example, some dishwashers have added ultraviolet sterilization functions to achieve better tableware disinfection purposes.
shortcoming:
Ultraviolet light can only kill bacteria on a surface of 2mm.
