The heating time (min) required to kill a certain concentration of microorganisms at a certain temperature. Usually refers to the lethal state of heating at 12℃. Is the lethal value of heating sterilization, which can be used to measure the sterilization intensity. The heating time required to kill a certain number of microorganisms or spores at a certain constant temperature (12℃) is regarded as the standard value to judge the rationality of a certain sterilization condition, also known as the standard F value, which is expressed by F-ampere. F-An means that the sterilization time required to meet the requirements of the spoilage rate of canned food is 12℃. For example, F-An of a canned food is 3min, which usually means that the canned food needs to be sterilized at 12℃ for 3 min. The standard sterilization time required for each can (usually 121℃ is the standard temperature), just like other food standards, is used as a reference to judge whether sterilization is qualified or not, and it is also the main basis for determining the constant temperature time τ2 in the sterilization formula.

when F-solid and F-A are used together, F-solid is equal to or slightly greater than F-A, so sterilization is reasonable; If F is less than F, the sterilization is insufficient and fails to meet the standard, which will cause food corruption and the sterilization time must be extended. F is much larger than F-An, and excessive sterilization and super-standard sterilization affect the color, flavor and nutritional value of canned food, which requires shortening the sterilization time. Through this comparison and repeated adjustment, the suitable constant temperature time τ2 can be found. For specific methods, please refer to the Canning Industry Manual, New Food Sterilization Technology, Food Canning Technology and A Complete Course in canning.