Effect of temperature on chlorine dioxide inactivation of Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes on spinach, tomatoes, stainless steel, and glass surfaces

The objective of this study was to evaluate how treatment temperature influences the solubility of ClO2 gas and the antimicrobial effect of ClO2 gas against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on produce and food contact surfaces. Produce and food contact surfaces inoculated with a combined culture cocktail of three strains each of the three foodborne pathogens were processed in a treatment chamber with 20 ppmv ClO2 gas at 15 or 25 °C under the same conditions of absolute humidity (11.2-12.3 g/m3) for up to 30 min. As treatment time increased, ClO2 gas treatment at 15 °C caused significantly more (p < 0.05) inactivation of the three pathogens than treatment at 25 °C. ClO2 gas treatment at 25 °C for 30 min resulted in 1.15 to 1.54, 1.53 to 1.88, and 1.00 to 1.78 log reductions of the three pathogens on spinach leaves, tomatoes, and stainless steel No.4, respectively. ClO2 gas treatment at 15 °C for 30 min caused 2.53 to 2.88, 2.82 to 3.23, and 2.37 to 3.03 log reductions of the three pathogens on spinach leaves, tomatoes, and stainless steel No.4, respectively. Treatment with ClO2 gas at 25 °C for 20 min resulted in 1.88 to 2.31 log reductions of the three pathogens on glass while >5.91 to 6.82 log reductions of these pathogens occurred after 20 min when treated at 15 °C. Residual ClO2 levels after gas treatment at 15 °C were significantly (p < 0.05) higher than those at 25 °C. The results of this study can help the food processing industry establish optimum ClO2 gas treatment conditions for maximizing the antimicrobial efficacy of ClO2 gas.