Optimization of Retort Temperature Profile Using Optimal Control Theory

In the sterilization process for foods packed in cans or retortable pouches, it is of importance to reduce quality deterioration of packed foods, achieving a certain level of sterilization. For this purpose, the optimum retort temperature profile is investigated in this paper. The optimal control theory was used to determine the optimum retort temperature profile for maximizing quality retention for a given final sterility value during the heat sterilization of conduction heating foods in flat containers. This is a constrained optimal control problem with an unspecified terminal time. The conjugate gradient minimization method is applied to this problem. The results show that the best profile can nearly be approximated by a ramp function.