Efficacy of Hydrogen Peroxide Vapor Treatment against Foodborne Pathogens on Fresh Produce

Abstract

In this study, the efficacy of hydrogen peroxide vapor (HPV) for reducing Salmonella Typhimurium, Escherichia coli O157: H7 and Listeria monocytogenes on spinach and lettuce was investigated as well as its effect on the quality used preliminary HPV treatment system and optimized HPV treatment system. The mechanism responsible for HPV treatment on bacterial cells was also studied using Transmission Electron Microscopy (TEM). Spinach and lettuce were inoculated with a cocktail containing three strains of each pathogen then treated with vaporized hydrogen peroxide for 0, 2, 4, 6, 8 and 10 min. The concentrations of hydrogen peroxide used were 0, 1, 3, 5 and 10%. With increasing treatment time and hydrogen peroxide concentration, HPV treatment showed significant (P < 0.05) reduction compared to the control (0%, treated with vaporized distilled water). In particular, vaporized 10% hydrogen peroxide treatment for 10 min was the most effective combination to reduce the three pathogens on spinach and lettuce. The reduction levels of S. Typhimurium, E. coli O157: H7 and L. monocytogenes on spinach were 4.40, 3.99 and 4.08 log10 CFU/g, respectively at preliminary HPV treatment system. And the reduction levels of S. Typhimurium, E. coli O157: H7 and L. monocytogenes on lettuce were 3.12, 3.15 and 2.95 log10 CFU/g, respectively at optimized HPV treatment system. Additionally, there were no significant (P > 0.05) differences between the levels of cells enumerated on the appropriate selective agar when injured cells were enumerated during the most of whole treatment time. Furthermore, there were no significant (P > 0.05) quality changes (color, texture, and ascorbic acid contents) of spinach and lettuce among all tested samples, and hydrogen peroxide residue were not detected after 36 hr storage time in any of the treated samples. TEM showed significant damage in the cell cytoplasm and cytoplasmic membrane after treatment with HPV. Our results suggest that HPV treatment might be used as an alternative treatment to control S. Typhimurium, E. coli O157: H7 and L. monocytogenes on fresh produce.