Antimicrobial effect of chlorine dioxide gas against foodborne pathogens under differing conditions of relative humidity

Abstract

The objective of this study was to determine the influence of relative humidity (RH) on the antimicrobial effect of chlorine dioxide (ClO2) gas against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on spinach leaves. Spinach leaves were inoculated with three foodborne pathogens and treated with ClO2 gas at different concentrations (1, 5, 10, 30, and 50 ppmv) for 0, 5, 10, 15, and 20 min under differing conditions of RH (50, 70, and 90%). Inoculated spinach leaves subjected to ClO2 gas treatments experienced significant reductions, with pathogen populations reduced more under conditions of 90% than under 50 and 70% RH. Generally, there were no significant differences (p > 0.05) in reduction levels of the three foodborne pathogens between 50 and 70% RH. Exposure to 50 ppmv of ClO2 gas for 20 min resulted in 1.25–1.78 (50% RH) and 2.02 to 2.54 (70% RH) log reductions of the three foodborne pathogens. The levels of the three foodborne pathogens was reduced to below the detection limit (1 log CFU/g) within 15 min when treated with 50 ppmv of ClO2 gas under 90% RH. The results may help the fresh produce industry to establish effective conditions for ClO2 gas treatment.