Submitted to: Journal of Food Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/8/2004
Publication Date: 10/28/2004
Citation: Huang, L. 2004. Numerical analysis of heat transfer during surface pasteurization of hot dogs with vacuum-steam-vacuum technology. Journal of Food Science. 69(9):E455-E464. Interpretive Summary: Vacuum-steam-vacuum (VSV) surface pasteurization was recently developed to kill foodborne pathogens, such as Listeria monocytogenes, attached onto food surfaces. This study proposed a new hypothesis governing the fundamental process of heat transfer during VSV. Also, we developed and validated a computer simulation model that describes the temperature distribution under the surface of hot dogs during VSV treatment. The findings provide a fundamental understanding underlying microbial inactivation by VSV processes. This study can be used by the food industry to develop processes for processing/preparing pathogen-free ready-to-eat foods.
Technical Abstract: The objective of this study was to validate the fundamental heat transfer mechanism governing the process of vacuum-steam-vacuum surface pasteurization of hot dogs. It was hypothesized that the steam could not directly flow into the pores below the surface of hot dogs, and the heat was transferred into these areas by conduction. A numerical analysis program was first developed to estimate the heat transfer coefficient between steam and hot dogs, and then used to simulate the temperature distribution at different locations below the surface. The hypothesis and computer simulation model were successfully validated using hot dogs surface-inoculated with L. innocua. Results showed that the heat from saturated steam must be conducted into the interior in order to kill Listeria innocua, a surrogate for Listeria monocytogenes, harboring in the pores and irregularities below the surface of hot dogs. Results of computer simulation and biological validation also suggested that heating must be maintained for at least 25s to achieve 80°C, at 1 mm below the surface of hot dogs, for a complete elimination (> 8 logs) of L. innocua.