Submitted to: Journal of Food Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 1, 2006
Publication Date: N/A
Interpretive Summary: Listeria monocytogenes is a foodborne pathogen that occasionally is a contaminant on ready-to-eat (RTE) foods such as frankfurters. Hot water can be used to eliminate L. monocytogenes in frankfurter packages. This research developed and validated a computer simulation model used for simulating the heat transfer process during hot water pasteurization of packaged frankfurters. The experimental results demonstrated that hot water could effectively inactivate L. monocytogenes during in-package pasteurization and render final products free of this microorganism. The computer simulation program can accurately simulate the internal temperature profiles and can be used to design or evaluate processes for in-package pasteurization of frankfurters in single layer packages.
Technical Abstract: The objective of this research was to develop methods for simulating the heat transfer process during the pasteurization of frankfurters 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. The computer program was then used to simulate the heat transfer processes during hot water pasteurization of frankfurters. The results of the 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 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 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.