Effects of Irradiation Dose and O2and CO2Concentrations in Packages on Foodborne Pathogenic Bacteria and Quality of Ready-to-Cook Seasoned Ground Beef Product (Meatball) during Refrigerated Storage

Combined effects of gamma irradiation and concentrations of O 2 (0, 5, 21%) and CO 2 (0, 50%) on survival of Escherichia coli O157:H7, Salmonella enteritidis , Listeria monocytogenes , lipid oxidation, and color changes in ready-to-cook seasoned ground beef (meatball) during refrigerated storage were investigated. Ground beef seasoned with mixed spices was packaged in varying O 2 and CO 2 levels and irradiated at 2 and 4 kGy. Irradiation (4 kGy) caused about 6 Log inactivation of the inoculated pathogens. Inactivation of Salmonella was 0.9- and 0.4-Log lower in 0 and 5% O 2 , respectively, compared to 21% O 2 . Irradiation at 2 and 4 kGy increased thiobarbituric acid reactive substances in meatballs by 0.12 and 0.28 mg malondialdehyde kg −1 , respectively, compared to control. In reduced-O 2 packages, radiation-induced oxidation was lower, and the initial color of an irradiated sample was maintained. Packaging with 0% + 50% CO 2 or 5% O 2 + 50% CO 2 maintained the oxidative and the color quality of irradiated meatballs during 14-day refrigerated storage. MAP with 5%O 2 + 50% CO 2 combined with irradiation up to 4 kGy is suggested for refrigerated meatballs to reduce the foodborne pathogen risk and to maintain the quality.