Studies on the potential use of chlorine dioxide for treatment of seafood products: Microbiology, nutritional analysis, and mutagenicity

Chlorine dioxide (ClO{dollar}sb2){dollar} has been considered a potential substitute for aqueous chlorine in treating seafood products. Its use for such treatment was examined on fillets of Atlantic salmon (Salmo sulur), red grouper (Epinephelus morio), mahi-mahi (Coryphaena hippurus), headless brown shrimp (Penaeus aztecus), white penaeid shrimp (Penaeus setiferus), calico scallops (Aequipecten gibbus), sea scallops (Placopecten magellanicus) and gutted whole Atlantic salmon and red grouper to determine its impact on reducing bacterial loads and improving the quality of treated products.; Bacterial loads and the sensory quality of selected seafoods stored on ice were evaluated from 0-7 days. Compared to nontreated controls and the brine treated group, treatment of red grouper and salmon fillets, and whole salmon with ClO{dollar}sb2{dollar} solutions on day 0 caused dose-related but nonsignificant decreases in numbers of natural bacterial flora. Scallops, shrimp, and whole red grouper treated with ClO{dollar}sb2,{dollar} however, showed significant decreases in bacterial numbers on day 0. Most samples treated and stored for 3 and 7 days also had decreased bacterial numbers with the higher ClO{dollar}sb2{dollar} treatment being significantly (P {dollar}<{dollar} 0.05) different from all controls. Although the pH of ClO, solutions increased following the dipping of all samples, the solutions after treatment contained very low or undetectable bacterial loads. Discoloration of treated seafood resulted at 100 or 200 ppm concentrations, with the skins of red grouper and salmon becoming lighter in color. The occurrence of a chocolate color in the gills was a major drawback for using high ClO{dollar}sb2{dollar} concentrations for whole fish.; Thiobarbituric acid (THA) values and fatty acid compositions were determined after ClO{dollar}sb2{dollar} treatments. Salmon and red grouper showed an increase in TBA; the 100 and 200 ppm groups had significantly greater TBA values than did the controls and 20 ppm group. Red grouper and salmon at 100 and 200 ppm ClO{dollar}sb2{dollar} did not differ in percent monounsaturated and polyunsaturated fatty acids compared to controls, although differences occurred with some individual fatty acids. Thus, ClO{dollar}sb2{dollar} treatment did not greatly affect fatty acid composition. Protein content of salmon and red grouper was also unaffected by ClO{dollar}sb2{dollar} treatments. However, ClO{dollar}sb2{dollar} caused significant reductions in thiamine for salmon and red grouper, and riboflavin for red grouper only. Levels of calcium, iron and phosphorus in red grouper fillets and phosphorus and potassium in salmon fillets were not affected following treatment with ClO{dollar}sb2{dollar} solutions.; Low levels of chlorate residues were detected in some of the treated seafood samples, but no chlorite residues were found in any of the treated seafoods. Extracts from ClO{dollar}sb2{dollar} treated solutions and treated fish fillets were found to be non-mutagenic to Salmonella typhimurium strains TA 98 and TA 100 with or without the S-9 mix. Since ClO{dollar}sb2{dollar} is a more potent bactericidal agent than chlorine and non-mutagenic, it can be used as a substitute for chlorine in the treatment of seafood to enhance freshness, extend shelf-life, and improve the safety of the products.