Effect of gamma rays on microbial quality of salmon fish during storage in refrigerator at 4 °C

Microbial quality, including total volatile counts (TVC), Entrobacteriaceae, Pseudomonaceae, and lactic acid bacteria (LAB) of salmon (Salmo trutta) irradiated at 0 (unirradiated), 2, 3, and 4 kg during 21 days of storage in a refrigerator (4 ± 1°C), was examined periodically (every 4 days). Unirradiated samples had higher bacterial counts than the others, and as the irradiation dose increased, the bacterial count decreased (P >0.05), as no LAB and Entrobacteriaceae were detected in the samples with 4 kg irradiation. The results showed that gamma irradiation inhibited bacterial growth in rainbow trout during storage at refrigeration temperatures. According to the results, the main effect of irradiation on microorganisms is due to the charged particles generated by irradiation, which are capable of breaking deoxyribonucleic acid (DNA). In the presence of water, cell damage during irradiation is due to both direct damage to cell DNA and indirect damage due to the reactivity of the radioactive products with cell components.