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Elimination of Listeria monocytogenes on Hotdogs by Infrared Surface Treatment


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ABSTRACT:  The objective of this research was to develop an infrared pasteurization process with automatic temperature control for inactivation of surface-contaminated Listeria monocytogenes on ready-to-eat meats such as hotdogs. The pasteurization system contained 4 basic elements: an infrared emitter, a hotdog roller, an infrared sensor, and a temperature controller. The infrared sensor was used to monitor the surface temperature of hotdogs while the infrared emitter, modulated by a power controller, was used as a heating source. The surface temperature of hotdogs was increased to set points (70, 75, 80, or 85 °C), and maintained for bacterial kill. The infrared surface pasteurization was evaluated using hotdogs that were surface-inoculated with a 4-strain L. monocytogenes cocktail to an average initial inoculum of 7.32 log (CFU/g). On the average 1.0, 2.1, 3.0, or 5.3 log-reduction in L. monocytogenes was observed after the surface temperature of hotdogs was increased to 70, 75, 80, or 85 °C, respectively. Holding the sample temperature led to additional bacterial inactivation. With a 3 min holding at 80 °C or 2 min at 85 °C, a total of 6.4 or 6.7 logs of L. monocytogenes were inactivated. This study demonstrated that the infrared surface pasteurization was effective in inactivating L. monocytogenes in RTE meats.