Descriptive Sensory Analysis of Irradiated Frozen or Refrigerated Chicken

Volatile profiles and lipid oxidation of irradiated cooked chicken meat from laying hens fed diets containing conjugated linoleic acid

The objective of this study was to determine the influence of dietary conjugated linoleic acid (CLA) on lipid oxidation, volatile profiles, and sensory characteristics of irradiated cooked chicken meat. Forty-eight 27-wk-old White Leghorn hens were fed a diet containing 0, 1.25, 2.5, or 5.0% CLA. After 12 wk of feeding trial, hens were slaughtered, and boneless, skinless breast and thigh muscles were separated. Meats of three birds from a dietary treatment were pooled and ground together through a 9-mm and a 3-mm plate, and patties were prepared. Patties were individually packaged and cooked in a water bath at 85 C for 15 min. After cooling to room temperature, patties were repackaged in oxygen-permeable or oxygen-impermeable bags, irradiated at 0 or 3 kiloGray (kGy) with an electron beam irradiator, and analyzed for lipid oxidation, volatile profiles, and sensory characteristics at 0 and 5 d of storage at 4 C. Cooked meat patties from hens fed CLA diets had lower TBA-reactive substances values and produced less hexanal and pentanal than the control. The irradiated and nonirradiated cooked chicken meat with aerobic packaging developed severe lipid oxidation during the 5-d storage at 4 C. Irradiation accelerated lipid oxidation in aerobic-packaged cooked chicken meat, but its effect was not as significant as that of the packaging. No odor differences were found among the cooked chicken meats from the different dietary CLA treatments. The increased storage stability of cooked meat from hens fed CLA diets was caused by the increased saturated fatty acids and CLA content in meat lipids. Tissue CLA was stable from oxidative changes and had minimal effect on volatile production in irradiated and nonirradiated cooked chicken meat during storage.

Reduction of normal flora by irradiation and its effect on the ability of Listeria monocytogenes to multiply on ground turkey stored at 7 degrees C when packaged under a modified atmosphere

Listeria monocytogenes did not multiply faster during storage at 7 degrees C on irradiated than on nonirradiated raw ground turkey, and there was a concentration-dependent inhibition of its multiplication by CO2. Ground turkey was gamma irradiated at 5 degrees C to 0, 1.5, and 2.5 kGy and inoculated (approximately 100 CFU/g) after irradiation with a cocktail of L. monocytogenes ATCC 7644, 15313, 49594, and 43256. The meat was then packaged in air-permeable pouches or under atmospheres containing 30 or 53% CO2, 19% O2, and 51 or 24% N2 and stored at 7 degrees C for up to 28 days. A dose of 2.5 kGy extended the time for the total plate count (TPC) to reach 10(7) CFU/g from 4 to 19 days compared to that for nonirradiated turkey in air-permeable pouches. Following a dose of 2.5 kGy at the end of the 28-day study, the TPCs were 10(6.42) and 10(4.98) under 25% and 50% CO2 atmospheres, respectively. Under air, 30% CO2, and 53% CO2 atmospheres, the populations of L. monocytogenes after 19 days incubation were 10(4.89), 10(3.60), and 10(2.67) CFU/g. The populations of lactic acid bacteria and anaerobic or facultative bacteria were also reduced by irradiation. Irradiating ground turkey did not decrease its safety when it was contaminated following processing with L. monocytogenes.

Effects of dietary vitamin E supplementation on lipid oxidation and volatiles content of irradiated, cooked turkey meat patties with different packaging

A study was conducted to determine the effects of dietary vitamin E supplementation on the storage stability and volatiles production in irradiated cooked turkey meat. Turkeys, raised with diets containing 25, 50, 75, or 100 IU of dl-alpha-tocopheryl acetate (TA)/kg diet from 1 to 105 d of age, were fed with diets containing 25, 200, 400, or 600 IU of TA/kg diet from 105 to 122 d of age. Breast and leg meat patties were prepared, irradiated at 0 or 2.5 kGy dose, cooked to an internal temperature of 78 C, and stored in either vacuum or aerobic packaging. Thiobarbituric acid reactive substance (TBARS) values gradually decreased as the dietary TA increased and > 200 IU TA/kg diet treatments were helpful in maintaining low TBARS values in irradiated breast and leg meat patties during the 7-d storage period. With vacuum-packaging, irradiated cooked breast patties developed more oxidation than nonirradiated patties but the prooxidant effect of irradiation in cooked leg meat patties was not consistent. In aerobic-packaged cooked meat, irradiated patties had lower TBARS than nonirradiated patties in both breast and leg meat stored in oxygen permeable bags for 7 d. Propanal, pentanal, hexanal, 1-pentanol, and total volatiles were highly correlated with the TBARS values of meat. However, hexanal represented the lipid oxidation status of cooked meat better than any other volatiles component. The amount of hexanal and total volatiles in cooked breast and leg meat shows decreasing trends as dietary TA increased. In vacuum packaging, irradiated breast and leg meat had higher hexanal and total volatiles content than nonirradiated meat at both 0 and 7 d of storage. In aerobic packaging, the amount of hexanal and total volatiles greatly increased in both irradiated and nonirradiated meat patties during the 7-d storage periods. The results illustrated that the antioxidant effect of TA was not strong enough to control lipid oxidation and off-odor generation in cooked meat stored under aerobic conditions because the progress of lipid oxidation in cooked meat under aerobic condition is very rapid. However, the combination of dietary TA and vacuum packaging of cooked meat immediately after cooking could be a good strategy to minimize oxidation and volatiles production in cooked meat.