| Summary: | 碩士 === 國立臺灣海洋大學 === 食品科學系 === 103 === Because food pathogens caused food poisoning, there are many studies focused on utilizing sanitizers to prevent foodborne pathogens - associated food intoxication in recent years. Although the traditional chlorine-based sanitizers have widely been used in food processing, they may cause safety suspension due to hazardous disinfection by-products (DBPs). Hence, using electrolyzed water as promising alternative sanitizer receives attention. In this study, attempts were made to evaluate the slightly basic electrolyzed water (SBEW) on the growth of Escherichia coli and Listeria monocytogenes. The results showed that SBEW with 200 ppm available chlorine concentration (ACC) could respectively kill E. coli and L. monocytogenes for 15 sec and 2min. SBEW kills E. coli and L. monocytogenes in dose (ACC content) and time dependent. In addition, SBEW with 50 ppm ACC didn’t affect the growth of E. coli and L. monocytogenes immediately, but their lag phases were prolonged by SBEW. Moreover, Gram-negative bacteria were more vulnerable to SBEW than Gram-positive bacteria. As comparing the bactericidal effect, the bactericidal activity of SBEW on E. coli and L. monocytogenes was worse than acidic electrolyzed water (AEW), but better than sodium hypochlorite. Simultaneously, the disinfection mechanism of SBEW was also investigated in the study. The results showed that the changes of protein expression in SBEW-treated L. monocytogenes and E. coli were also demonstrated by using sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE). There are many protein bands of both test strains got fainter and even disappeared. Furthermore, the two dimensional electrophoresis (2DE) revealed that proteins were changed in expression, and a spot may be outer membrane protein A (OmpA) related with osmotic pressure regulation. The bactericidal efficacy of SBEW against L. monocytogenes and E. coli on mung bean sprouts and nectarines was evaluated and compared to AEW and sodium hypochlorite solution. The results showed that the bactericidal efficacy and Hunter color values were increased when processing time was increased. The optional processing time in mung bean sprout and nectarines treated with SBEW was 10 min. In summary, the results illustrated that SBEW could be used as a sanitizer of L. monocytogenes and E. coli. Besides, the bactericidal activity of SBEW on E. coli and L. monocytogenes was worse than AEW, but better than sodium hypochlorite.
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