Effect by Gamma Irradiation and Low-Temperature Storage on Bacteriological Profile of Edible Estuarine Crab Scylla serrata

The effect of dose‐dependent gamma irradiation and subsequent cold storage on bacteriological profile of tissues derived from Scylla serrata was evaluated. Irradiation at 0.5, 1.0 and 2.0 kGy significantly reduced the (P = 0.0001) total plate count (TPC) by 1.0, 2.0 and 2.5 log units, respectively. Treatments of 1.0 and 2.0 kGy irradiation reduced total coliform (TC) count below 1 most probable number (MPN)/g in the muscle and hepatopancreas and below 50 MPN/g in the gills of S. serrata. Irradiated tissues stored at −20C showed significant reduction in TPC and TC. Bacillus spp. was predominant in the tissues before and after gamma irradiation. While live crab tissues harbored both gram‐positive and gram‐negative bacteria in equal proportion, more than 90% of them from irradiated tissues were gram‐positive. Biochemical and 16S rRNA gene‐based study on generic composition of heterotrophic bacteria revealed fairly good diversity in nonirradiated tissues and the dose‐dependent gamma irradiation significantly reduced their diversity concomitantly. Practical Applications The mud crab Scylla serrata in which the present study was conducted has immense market demand all over the world. The present study clearly demonstrated the possibility to utilize gamma irradiation to reduce the microbial contamination and thereby extend the shelf life of this expensive shellfish under refrigerated temperatures.