Effect of gamma irradiation on total bacterial load and total volatile nitrogen in fish rainbow trout meat during refrigerator condition

Aquatics, including fish, have always been one of the most perishable protein sources. For increasing storage time of the resource there are several ways including radiation.  The effect of gamma irradiation was investigated on the microbial load and total volatile nitrogen of fish meat rainbow trout (Oncorhynchus mykiss). At the beginning of these experiment, the fish meat is irradiated by 1.5, 2.5 and 3.5 KGry radiation doses and subsequently transferred to the refrigerator at 4°C. During the first, seventh and fourteenth days after irradiation (after transfer to the refrigerator) the total amount of bacteria and total volatile nitrogen was investigated. The results indicated a greatly reduction of amount of bacterial load and total volatile nitrogen by the use of various doses of gamma irradiation. Among the irradiated doses, 3.5 KGry showed the greatest decrease in these parameters, but considering that there was not huge difference between 2.5 and 3.5 KGry in the reduction, thus 2.5 KGry gamma irradiation is selected as a suitable dose for rainbow trout irradiation and subsequent storage in the refrigerator.