Submitted to: Journal of Food Safety
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 27, 2006
Publication Date: July 1, 2007
Citation: Sommers, C.H., Niemira, B.A. 2007. Effect of temperature on the radiation resistance of yersinia pestis suspended in raw ground pork. Journal of Food Safety. 27:317-325. Interpretive Summary: Yersinia pestis is the bacteria that causes plague. Humans can contract pharyngeal plague through the consumption of meat contaminated with Y. pestis. The risk of contracting plague from the consumption of meat deliberately contaminated with Y. pestis is unknown. Ionizing radiation is a safe and effective process that inactivates pathogenic bacteria in meat. In this work avirulent Y. pestis was inoculated into raw ground pork that was then irradiated at different temperatures. Y. pestis was more resistant to irradiation when the meat was frozen as opposed to refrigerated. A predictive equation was developed to describe the effect of temperature and radiation dose on the inactivation of Y. pestis in raw meat. This information can be used by the government agencies and the radiation processing industry to protect consumers from intentional contamination of the meat supply with the bacteria that causes plague.
Technical Abstract: Yersinia pestis is the causative agent of plague. While rare, pharyngeal plague in humans has been associated with consumption or handling of meat prepared from infected animals. The risks of contracting plague from consumption of deliberately contaminated meat are currently unknown. Ionizing radiation can inactivate foodborne pathogens including Escherichia coli O157:H7, Salmonella spp., Staphyloccocus aureus, Listeria monocytogenes, and Yersinia enterocolitica in refrigerated and frozen raw meat. The radiation resistance of avirulent Y. pestis suspended in raw ground pork was 0.16 (0.02), 0.27 (0.02), 0.36 (0.02) and 0.54 (0.03) kGy when irradiated at temperatures of 10, 0, -10 and -20C, respectively. When incorporated into a 3D mesh, the predictive equation followed a parabolic fit (R2=0.84) where log10 reduction = - 0.264 - (0.039 x Temp) - (3.833 x Dose) - (0.0013 x Temp2) - (0.728 x Dose2). A radiation dose of 1.35 kGy would inactivate 5 log10 of Y. pestis in refrigerated (0C) ground pork, while a radiation dose of 2.7 kGy would be required for frozen (-20C) product. These results indicate that Y. pestis could easily be controlled in refrigerated and frozen raw ground meat using ionizing radiation.