Effect of Gamma Radiation at-20°C on Microbiological Changes in Wild and Cultured Stinging Catfish, Heteropneustes fossilis

Abstract

Quality and shelf life of non-irradiated (control) and irradiated (1.5 and 3 KGy) stinging catfish (Heteropneustes fossilis) stored at-20°C were investigated by microbiological analysis. The main concern was to evaluate the efficiency of gamma radiation as a preservation method in combination with low temperature (-20°C) refrigeration for keeping the quality and shelf-life extension of two types (wild and culture) of degutted stinging catfish for 60 days storage period. Total bacterial count (TBC), total mould count (TMC) and total yeast count (TYC) were obtained higher in wild fish than those of cultured one. Significant differences (p<0.05) were observed among treated groups (0, 1.5 and 3 KGy) for total bacterial, mould and yeast counts in both wild and cultured fish meanwhile within storage duration (1, 7, 15, 30, 45 and 60 days), the trend was converse. Significantly higher values (p<0.05) for TBC, TMC and TYC were obtained for non-irradiated wild and cultured samples, whereas at 1.5 and 3 KGy the values were significantly lower for both fish sources after 60 days. But during the storage period, all the values were found at slow increasing trend in all treated groups for both wild and cultured fish. On the contrary, total coliform count (TCC) and Salmonella were absent in both of them for the entire storage period. This study reveals that gamma radiation in combination with low temperature (-20°C) refrigeration showed maximum shelf-life extension (60 days) in each dose of radiation used but 3 KGy irradiated both wild and cultured H. fossilis were found with the best quality.