ABSTRACT
The most important factor for bacterial inactivation during thermal processing of canned food is sterilization value or cumulative lethality. Aseptic processing involves sterilization of the food product and package separately and filling of the sterilized product in a sterile environment. In controlling thermal processes, the objective is to meet the desired level of bacterial inactivation for the process, irrespective of any variation in the input and reference conditions and with a minimum of overprocessing. Fourier's equation of heat transfer is usually used to model heat penetration in conduction-heated canned foods. In the computerized determination of parameters for the step-response model, made prior to the main sterilization, it is possible to correct values of parameters by fitting the model to the measured temperature data. A computer-based controller should be programmed to perform various control actions. Most important are the feed-forward control of bacterial inactivation, and the feedback control of retort temperature.
