LETHALITY OF THERMAL-PROCESSES FOR FOOD IN ANOMALOUS-SHAPED PLASTIC CONTAINERS

A numerical simulation was performed to obtain the temperature distrib ution in a bowl-shaped plastic container with a metal lid. The boundar y conditions included the first and third kinds, which were applied to the lid and the plastic parts, respectively. Due to the curvilinear b oundary, a finite volume numerical method was used to calculate the no dal temperature, which was verified experimentally. The location of th e lowest temperature (cold point) during heating was found by temperat ure interpolation and rearrangement of nodal points. It was found that the cold point of the bowl-shaped container, using a circulating supe rheated water-type retort, was located at 0.46 H on the rotating axis above the bottom. However, the lowest calculated total lethality, when including the cooling phase, was at 0.4 H and was 1% to 2% less than the lethality of the cold point (the lowest temperature in the heating phase).