Calculation of Optimum Sterilization Conditions for Packed Conduction‐type Foods

The basis of the method is the short‐cut calculation procedure developed by Thijssen et al. (1978) for sterilization conditions yielding optimum quality retention for conduction heating of packed foods at constant temperatures of the heating and cooling medium. This method is improved and extended to variable temperatures of the heating and cooling medium as occur in continuous sterilizers. This is done by converting the variable temperature into a block temperature‐time relationship. By means of computer simulations of the sterilization process, the variable heating temperature is converted into a constant heating temperature and an increased homogeneous initial product temperature yielding the same lethal effect. The variable cooling temperature is converted into a constant cooling temperature and an additional heating time at constant retort temperature yielding the same lethal effect as is obtained during the actual cooling process. On the block temperature‐time diagram thus obtained the short‐cut calculation method is again applicable. The error introduced by this method in the calculated logarithm of the reduction of microorganisms is less than 20%.