Effect of Gamma Radiation on the Microbial Characteristics of Golden Gray Mullet (Lizaaurata) Fillet during Chilled Storage (4°C)

Golden gray mullet (Lizaaurata) is one of the valuable fishes inhabited in Caspian Sea, which is captured in large volumes in northern parts of Iran. However, similar to other fishes, Golden gray mullet is susceptible to bacterial spoilage and the quality of the fish will be degraded during the storage time. Therefore, the purpose of the present study was to investigate the effects of gamma radiation, as a non-thermal fish processing method, on the microbiological properties and shelf-life extension of Golden gray mullet fillets during chilled storage (4° C).Experimental fish were filleted, irradiated at different doses (0, 1, 2, 3 and 5 kGy) and then stored in refrigerator for 35 days. Microbial quality changes were evaluated by enumeration of total viable count (TVC), Pseudomonas, Lactic acid bacteria (LAB), H2S producing bacteria and Enterobacteriaceae over the experimental period on the day of 1, 5, 10, 15, 20, 25, 30 and 35. The results obtained from this study showed that the shelf life of Golden gray mullet stored at the refrigeration temperature, as determined by overall microbial load, is 10 days for non-irradiated Golden gray mullet. However, samples treated with gamma irradiation showed better quality during storage. The results revealed that radiation at a high dose (5 kGy) was inhibited the growth of microorganisms, and irradiation at a medium dose of 3 kGy could be used to control the microbial load indices of Golden gray mullet for up to 35 days at the refrigeration temperature without adverse effects on the fish quality and acceptability.