Application of combined UV-C light and ethanol treatment for the reduction of pathogenic Escherichia coli and Bacillus cereus on Gwamegi (semidried Pacific saury)

Abstract

This study investigated the combined effects of different doses of UV-C light at 260 nm (0-1,800 mWs/cm(2)) and ethanol (0-70%) on the reduction of Escherichia coli and Bacillus cereus in experimentally contaminated Gwamegi (semidried Pacific saury). After combined treatment of 4,800 mWs/cm(2) of UV-C and 70% ethanol, E. coli and B. cereus were reduced by 3.03 and 2.73 log CFU/g, respectively. However, quality losses of the product, including changes in pH, the thiobarbituric acid-reactive substances value, and color occurred after storage for 2 weeks at 5 degrees C. The results suggested that a combination of 2,400 mWs/cm(2) of UV-C and 70% ethanol could potentially be used to inactivate E. coli and B. cereus in this dried fish product during storage for 7 days without any adverse changes in the qualities of the fillets. Practical Applications Since Gwamegi is traditionally air-dried in the open, it could easily become contaminated by pathogens. Treatment with the combination of UV-C (2,400 mWs/cm(2)) and ethanol (70%) is optimal to prevent microbial proliferation on the product during drying without causing organoleptic changes. Despite the cost, this hurdle technology can be applied in the small fishery industry.