Irradiation Inactivation of Listeria monocytogenes in Low-Fat Ground Pork at Freezing and Refrigeration Temperatures

• Published in: Journal of food protection 2006-12, Vol.69 (12), p.2955-2960
• Main Authors: Bari, M.L, Todoriki, S, Sommers, C, Hayakawa, F, Kawamoto, S
• Format: Article
• Language: English
• Subjects: Animals; bacterial contamination; Biological and medical sciences; cold storage; Cold Temperature; Colony Count, Microbial; Consumer Product Safety; cooked foods; cooling; Dose-Response Relationship, Radiation; food acceptability; food contamination; Food industries; food irradiation; Food Irradiation - methods; Food microbiology; food pathogens; Food Preservation - methods; Food Preservation - standards; food storage; Freezing; Fundamental and applied biological sciences. Psychology; gamma radiation; Gamma Rays; ground pork; Humans; Lipid Peroxidation; lipids; Listeria monocytogenes; Listeria monocytogenes - radiation effects; low fat foods; Meat and meat product industries; Meat Products - microbiology; Meat Products - standards; meat quality; oxidation; refrigeration; sensory evaluation; Swine; Taste; Thiobarbituric Acid Reactive Substances - analysis; thiobarbituric acid-reactive substances; Time Factors
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028X-69.12.2955

Gamma radiation effectively controls Listeria monocytogenes in uncooked and in ready-to-eat foods. This study was conducted to determine if gamma radiation could be used to control L. monocytogenes in ground pork. Ground pork was contaminated with L. monocytogenes, kept at refrigeration (4 degrees C), chilling (0 degrees C), and freezing (-18 degrees C) temperatures overnight, exposed to gamma radiation and stored at 4 degrees C for 7 days, and at 0 and -18 degrees C 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 sausage made from the irradiated and nonirradiated 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 radiation dose. The results of a 60-day storage study of ground pork inoculated with 10(5) to 10(6) CFU of L. monocytogenes per gram indicated that counts for nonirradiated meat remained fairly constant at refrigeration, chilling, and freezing temperatures. However, irradiation of ground pork at 3.0 kGy could inactivate L. monocytogenes totally in ground pork subsequently held at all the temperatures used in this study. Lipid oxidation measurements, as determined by the thiobarbituric acid-reactive substance assay, ranged from 0.16 nmol/g for nonirradiated ground pork and 0.20 nmol/g for meat irradiated at 3.0 kGy. Sensory panelists could distinguish between irradiated and nonirradiated sausage but were divided on whether irradiation adversely affected the sausage quality. Our results suggest that gamma radiation could be useful to control L. monocytogenes in ground pork and improve the safety of ground pork products.