Lipid Oxidation, Volatiles, and Off-Odor Production of Aerobic-Packaged Pork Patties Irradiated and Stored in Refrigerated or Frozen Conditions

Pork loins were ground twice through a 9-mm plate and patties (approximately 80 g each) were made. Patties were individually packaged in oxygen-permeable polyethylene zipper bags, stored overnight either at 4 or-40 C, and irradiated the next day at 0, 1.5, 3.0, or 4.5 kGy absorbed dose for refrigerated patties, and at 0, 2.5, 5.0, or 7.5 kGy for frozen ones. Samples were analyzed for lipid oxidation, volatile production, and off-odor. Refrigerated samples were analyzed at 0, 1 and 2 weeks of storage at 4°C, and frozen ones were analyzed after 0, 1.5 and 3 months of storage at-40°C. 2-Thiobarbituric acid reactive substances (TBARS) of refrigerated pork patties increased with storage time. TBARS of pork patties increased as irradiation dose increase at 0 day, but the irradiation-dose effect disappeared after 1-week of storage at 4°C. Irradiated pork patties produced significant irradiation odor at day 0, but disappeared following storage. Nonirradiated samples were preferred to the irradiated ones at beginning (day 0), but the preference disappeared after 1-week of storage. With frozen storage, TBARS values of irradiated pork patties were not increased by storage. However, patties irradiated at higher dose (7.5 kGy) had higher TBARS value than the nonirradiated or irradiated patties at lower levels. Nonirradiated patties had higher preference scores than the irradiated ones and the difference lasted for 1.5 month in frozen storage. Sulfur-containing compounds such as 2,3-dimethyldisulfide were responsible for most of the irradiation off-odor, but volatilized quickly under aerobic conditions. However, aerobic packaging was not recommended for irradiated meat because of oxidative changes in pork patties during storage