• optimization;
  • thermal processing;
  • retort temperature;
  • cook-value;
  • retortable pouch


The optimal control theory was used to determine the optimum retort temperature profile for quality retention at a given level of sterilizing value in conduction-heating of foods in retortable pouches. The cook-value (C-value) was employed to describe quality changes. Optimization was considered to be a constrained optimal control problem with unspecified terminal time, and it was solved numerically, using the conjugate gradient minimization method. Optimum retort temperature profiles were determined for the volume average and surface C-values for browning reactions. Final C-value for volume average decreased by 10% as compared with that for optimum constant retort temperature, and the value for surface decreased by 30%. This method may be applicable to heat sterilization of canned foods as well.