Abstract
Chicken breast fillets were equally divided into three groups. One group was vacuum packaged, cooked in a water bath (cooked-in-bag) at 82 C for 25 min, and then irradiated at 0 or 3 kGy with a linear accelerator (V-C-I). The other two groups were irradiated at 0 or 3.0 kGy in vacuum packaging (V-I-C) or aerobic packaging (A-I-C). After 3 d of storage at 4 C, the irradiated meats were cooked in a water bath (cooked-in-bag) at 82 C for 25 min. After being cooked, meats were repackaged under vacuum and stored at 4 C. Breast fillets were analyzed at 0 and 21 d after cooking and analyzed for lipid oxidation, color, and volatiles. Irradiation accelerated lipid oxidation of breast fillets. Three days of storage of raw meat in aerobic conditions after irradiation had only minor influences on lipid oxidation after cooking. However, irradiation had a significant effect on the volatile production in meat. Dimethyl disulfide, related to irradiation odor, was significantly higher in irradiated fillets than in nonirradiated fillets for V-C-I and V-I-C, whereas it was only slightly higher for A-I-C. Other volatiles, such as 3-methyl butanal and 2-methyl butanal, were also produced in significant amounts after irradiation, especially in V-C-I and V-I-C. These results showed that irradiating cooked meat induced slightly more changes in volatiles than irradiating raw meat and then cooking. The amount of dimethyl disulfide between irradiated and nonirradiated samples for A-I-C was not different, because the dimethyl disulfide produced by irradiation disappeared during the 3 d in aerobic storage before cooking. Color a* value of irradiated fillets was higher than that of nonirradiated fillets. Irradiation also induced color L* and b* value changes. After 3 d of aerobic storage after irradiation of raw meat, the influence of irradiation on color after cooking was reduced. No significant lipid oxidation occurred during storage as shown by the low values for TBA-reactive substances.