Thermal sterilization is still the most important and effective method of food sterilization. According to the different process temperatures, thermal sterilization is usually divided into pasteurization, high temperature sterilization and ultra-high temperature sterilization. Pasteurization refers to the heating treatment below the boiling point of water (100%). Pasteur, a Frenchman, first analyzed the sterilization mechanism, which is often used in acidic foods with pH lower than pH4.5.

Retort pouch pressure heating high temperature sterilization process can be divided into intermittent and continuous. The heating medium can be saturated steam, steam-air mixture or hot water. Due to the low mechanical strength and sealing strength of retort pouch materials, the sterilization equipment must adopt back pressure sterilization. For retort pouch, the method of constant pressure and back pressure is mainly adopted. This back pressure control method is to introduce compressed air in the sterilization and heating stages.

Extended data:

Because low-temperature sterilization can't kill all microorganisms, especially spores, it needs to be preserved at low temperature, but the shelf life is only 3 months at most. In order to prolong the shelf life, canned food (including canned food and soft packaging) should be sterilized at high temperature and high pressure (that is, 12 1℃, which can be preserved for more than 2 years. However, in order to ensure the fragrance, the current manufacturers generally only stipulate the shelf life of half a year or one year.

High-temperature sterilization requires packaging materials with high partition and certain cooking resistance, such as tinplate, aluminum foil bag and PVDC film. Commonly used autoclaving equipment includes vertical, horizontal and continuous.

References:

Baidu encyclopedia-high temperature sterilization