The Effect of Gamma Radiation on Prerigor Mortis Filleted Cod
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The effect of gamma radiation on cod fillets was studied. Cod caught off the west coast of Norway were immediately filleted after slaying, packed in plastic bags and irradiated at the Institute of Atomic Energy, Kjeller. The doses were 25, 50, 90 and 180 krad. Irradiated and nonirradiated fillets were stored at 0 °C and analysed at intervals with respect to proteolytic activity, total bacterial count, trimethylamine (TMA), total volatile base (TVB), volatile acids (VA), hypoxanthine and glutamate-oxalacetate-transaminase (GOT). In irradiated cod fillets the proteolytic activity was considerably lower than in nonirradiated fillets. The proteolytic activity is correlated with the bacterial count, which was significantly decreased by irradiation. Correspondingly, TMA, TVB, VA and hypoxanthine formation were retarded by irradiation. The GOT concentration was lower in irradiated fillets than in nonirradiated. During the first days after irradiation a crab-like odour could be registered in fillets receiving 90 and 180 krad. This special odour disappeared gradually and irradiated fillets were found to be organoleptically acceptable after 27 days storage at 0°C, compared to 14 days for nonirradiated fillets.