Robust optimal receding horizon control of the thermal sterilization of canned foods

Open loop optimal control strategies for the thermal sterilization of canned foods are computed and analysed. The optimal retort temperature profiles ensure that the required degree of sterilization is met whilst minimising costs. The costs are defined in terms of batch time and retention of nutrient value in the food material. The model is a finite dimensional approximation of the infinite dimensional system. The errors due to the finite dimensional approximation and the uncertainty in the thermal diffusivity parameter of the model are considered. Based on the analysis a closed loop receding horizon optimal controller is designed. Simulation experiments reveal the robustness of the receding horizon optimal controller with respect to uncertainty in the thermal diffusivity parameter. The simulations also reveal that the loss of performance is relatively small and that the batch-time may be reduced significantly.