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item Huang, Lihan

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/2004
Publication Date: 7/11/2004
Citation: Huang, L. 2004. Engineering analysis of vacuum-steam-vacuum surface pasteurization processes. Institute of Food Technologists. Paper No. 17H-23.

Interpretive Summary:

Technical Abstract: Vacuum-steam-steam, or VSV, is a ultra-fast pasteurization technology developed for killing pathogens on the surface of solid foods, such as hot dogs. Studies published in the scientific literature show that large numbers of bacteria survived after VSV treatments. The objective of this study was to understand the fundamental mechanisms governing the process of VSV. A high-speed instrumentation system was used to measure the surface temperature of hot dogs during VSV processes. Results indicated that the pressure in the treatment chamber responded immediately and accurately to the events of VSV. The surface temperature history, however, did not instantaneously reach the steam temperature, but followed an exponential trend after saturated steam was flushed into the treatment chamber. A mathematical model was developed to simulate the surface temperature history during steam pasteurization processes. Using the mathematical model to estimate the lethality of VSV processes, it was found that treating with 110°C steam for 0.1 s should be sufficient to achieve a 5-log reduction in L. innocua inoculated onto the surface of hot dogs, provided that the surface was perfectly smooth and bacteria were all distributed on the surface. Due to the slow rate of heat penetration, bacteria hiding in small pores beneath the surface of solid foods may survive the VSV processes. A numerical model was further developed to simulate the processes of VSV surface pasteurization of hot dogs. This model could be used to design the VSV processes and achieve a complete destruction of Listeria monocytogenes on the surface ready-to-eat meat products.