Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2006
Publication Date: 12/1/2006
Citation: Bari, M.L., Mochida, M., Sommers, C.H., Hayakawa, F., Todoriki, S., Kawamoto, S. 2006. Irradiation inactivation of listeria monocytogenes in low fat ground pork at frozen and refrigerated temperature. Journal of Food Protection. 69:2955-2960. Interpretive Summary: Listeria monocytogenes is a foodborne pathogen responsible for many incidences of illness every year. Ionizing radiation is a safe and effective technology that can be used to improve the safety of foods. In this study the ability of ionizing radiation to inactivate L. monocytogenes in low fat raw ground pork was investigated. Irradiation was able to inactivate 99.999 percent of the pathogen at temperatures of 4, 0, and -18C with minimal effects on pork quality. Meat producers and regulatory agencies can use this information to provide safer pork products to consumers.
Technical Abstract: Gamma irradiation effectively controls Listeria monocytogenes in uncooked and in ready-to-eat foods. This study was conducted to determine if gamma irradiation could be used to control L. monocytogenes in ground pork. Ground pork was contaminated with L. monocytogenes, kept at refrigerated (4C), chilled (0C), and frozen (-18C) temperatures overnight, exposed to gamma irradiation and stored at 4C for 7 days, 0C, and -18C for 60 days. Following irradiation, the meat was assayed for L. monocytogenes viable counts and lipid oxidation. A triangle test was performed to determine if non-inoculated sausage made from irradiated and non-irradiated ground pork differed in sensory quality. It was observed that a 5-log reduction of L. monocytogenes viable counts would require a 3.0 kGy irradiation dose. The results of a 60-day storage study of ground pork inoculated with 10(5)-10(6) CFU of L. monocytogenes per g indicated that counts for non-irradiated meat remained fairly constant at refrigerated, chilled, and frozen temperature. However, irradiation of ground pork with 3.0 kGy could inactivate L. monocytogenes totally at all temperatures used in this study. Lipid oxidation measurements, as determined by the TBARS assay, ranged from 0.16 nmol/g for unirradiated ground pork and 0.20 nmol/g for meat irradiated at 3.0 kGy. Sensory panelists were able to distinguish between irradiated and non-irradiated sausage but were divided on whether irradiation adversely affected the sausage quality. Our results suggest that gamma irradiation may be useful to control L. monocytogenes in ground pork and improve the safety of pork products.