Computer simulation of heat transfer during in-package pasteurization of beef frankfurters by hot water immersion

The objective of this research was to develop methods for simulating the heat transfer process during pasteurization of frankfurter in single layer packages by hot water immersion to inactivate Listeria monocytogenes. A computer simulation program based on finite difference analysis was developed to simulate the temperature distributions within the frankfurter packages. This program was first used to estimate the apparent thermal diffusivity and surface heat transfer coefficients during the heating and cooling of frankfurters. Then this computer program was used to simulate the heat transfer processes during hot water pasteurization of frankfurters. The results of computer simulation indicated that the simulated temperature histories were in close agreement with the experimentally observed curves, both at the center and on the surface of the packages. The computer simulation model was biologically validated with frankfurters surfaced-inoculated with freshly grown L. monocytogenes. The observed bacterial reductions were generally 1–2 logs higher than those calculated by the General Method when the heating time was short. The theoretical calculation was more accurate when the heating time was long and the total inactivation was >5 logs. In general, the result of computer simulation for calculating the log reduction was more conservative than the experimental observations, therefore suitable for designing processes to ensure the safety of products and to reduce the incidence of foodborne listeriosis associated with RTE meats.