Increased Sensitization of Shrimp Microflora to Hypochlorite following a Sodium Bisulfite Dip¹

Various concentrations of hypochlorite (12.5 to 200 ppm) and sodium bisulfite (0.15 to 2.50%) applied singly and as successive dips were compared for their effect on the microbial flora of shrimp. It was found that sodium bisulfite exhibited antimicrobial activity at all concentrations tested, with a 50% reduction in bacterial numbers at a concentration of 2.5%. Hypochlorite reduced the bacterial load 75% at a concentration of 200 ppm. Under certain conditions a sequential treatment of shrimp with bisulfite, followed by a hypochlorite dip, significantly increased the antimicrobial effectiveness of the hypochlorite. This synergistic effect, however, was not apparent on shrimp following 24 h of iced storage.