On-line control strategy for compensating for arbitrary deviations in heating-medium temperature during batch thermal sterilization processes

The proposed strategy based on sets of sensitivity functions and total differential permits on-line control of batch thermal sterilization of convection- and conduction-heated canned foods of arbitrary shape. This approach enables the arbitrary fluctuations in heating-medium temperature to be compensated for by a correction of the heating turn-off. The computations are very simple, so standard micro-controllers are suitable for the process control. The errors associated with the application of the control strategy and especially the temperature deviations during the cooling period which are not taken into account and the discretization of process time are up to 3.5%. The proposed control strategy can be integrated into a HACCP framework as an on-line corrective action for compensating for the deviations in heating-medium temperature – the single critical control factor of the thermal sterilization process.