The synergistic effects of combined NaOCl, gamma irradiation and vitamin B1 on populations of Aeromonas hydrophila in squid

The present study investigated the synergistic disinfection effects of combined NaOCl/gamma irradiation and NaOCl/vitamin B1 treatment against Aeromonas hydrophila ATCC 7966 in tryptic soy broth (TSB) and squid. The synergistic effects were not dependent on the concentration of NaOCl or the dose of gamma irradiation, but were dependent on the vitamin B1 concentration. Synergistic values for NaOCl/gamma irradiation treatment in TSB and squid were −0.37 to 2.09 log10 CFU/mL and 0.00–2.92 log10 CFU/g, respectively. The largest synergistic values, 2.09 log10 CFU/mL in TSB and 2.92 log10 CFU/g in squid, were as a result of treatment with a combination of 40 ppm NaOCl and 1.0 kGy gamma irradiation and 80 ppm NaOCl and 2.0 kGy gamma irradiation, respectively. Synergistic values for NaOCl/vitamin B1 treatment in TSB and squid were 0.59–2.98 log10 CFU/mL and 0.06–1.35 log10 CFU/g, respectively. The largest synergistic values, 2.98 log10 CFU/mL in TSB and 1.35 log10 CFU/g in squid, were as a result of treatment with a combination of 300 ppm NaOCl and 1000 ppm vitamin B1 and 1000 ppm NaOCl and 1000 ppm vitamin B1, respectively. The results in the broth study suggest that the combination of 40 ppm NaOCl and 1.0 kGy gamma irradiation and 300 ppm NaOCl and 1000 ppm vitamin B1 could be regarded as a potential optimum hurdle approach for application to real target foods and(or) food surfaces for the control of A. hydrophila. Moreover, the results in the food study indicate that the combination treatment of 80 ppm NaOCl and 2.0 kGy gamma irradiation and 100 ppm NaOCl and 1000 ppm vitamin B1 could possibly be used in seafood production, processing, and distribution processes to enhance seafood safety.