AbstractsBiology & Animal Science

The quality of radiation-pasteurized halibut stored at 34°F was evaluated subjectively and objectively over a period of 18 weeks. Results of flavor evaluation and chemical analyses showed that the storage life of halibut irradiated at 0.50, 0.75 and 1.00 megarad was extended more than threefold. Although irradiated samples were consistently rated inferior to unirradiated reference sample by the taste panel, they remained in good condition throughout the 18-week period. No viable, aerobic microorganisms were found. Very little increase in trimethylamine nitrogen, volatile acid number and pH was observed. An increase in free amino nitrogen content was noted on the ninth week up to the twelfth week of storage after which a slight decrease was evident. Pasteurizing radiation was found to induce oxidative rancidity in ground halibut as determined by TBA number and peroxide value. Discoloration of the fish or rusting was observed in all irradiated samples except those treated with 0.005 percent of a commercial mixture of antioxidants, Tenox VI. Oxidative rancidity as measured by TBA number and peroxide value was also markedly inhibited by Tenox VI. Thiodipropionic acid used at the same concentration was found ineffective in preventing rancidity and rusting in the irradiated fish.