Even if it is not possible to attain absolute sterility, it is possible to sterilize food products for extended storage so that they are safe for human consumption. This degree of sterility is referred to as practical or commerical sterility. The F-Value is introduced as a standard on which to base the sterilization of food products. The F-Value is defined as the number of minutes which it takes to reduce the initial spore count of a certain microorganism to a desired safety level at a defined lethal reference temperature.
To determine the time period required for a certain sterilization process the following data is needed:
-The characteristic decimal reduction value of the endospores in the environment of the product
-Initial spore count per weight or volume unit (grams or ml) multiplied by the weight or volume of the product quantity in the container
-Desired maximal probable survival of spores in the thermal processed product
The technology to determine the required heat treatment beforehand in order to achieve commercial sterility is available not only for heat sterilized foods but for pasteurized products as well. The parameters of the heat process can be tailored using the determined treatment.
An important role in this case is the heat resistance of those organisms which may be destroyed between 60°C and 100°C. As in the case of sterilization, there is a symbol indicating the pasteurization value necessary for the sterility of the processed product which is the P-Value.