A pilot-scale evaluation of using gaseous chlorine dioxide for decontamination of foodborne pathogens on produce and low-moisture foods

Abstract

Small-scale studies have shown that chlorine dioxide gas, ClO2(g), was effective for decontamination of produce, nuts, and spices. This study conducted a pilot-scale evaluation to identify effective ClO2(g) treatment parameters for commercial-scale applications. The gas was produced by a generator utilizing sodium chlorite and chlorine gas for decontamination of Shiga toxin-producing Escherichia coli (STEC), Listeria monocytogenes, and Salmonella inoculated on tomatoes, blueberries, baby-cut carrots, almonds, and peppercorns. Inoculated samples and 45 kg tomatoes in a 1,246-L treatment chamber were exposed to various ClO2(g) concentrations (mg/L) and times 9 (hr) at 70-95% RH to determine the treatment effects on the pathogen reductions. Results showed that the treatment caused higher reductions on produce. A ClO2(g) treatment of 1 mg/L-3 hr at 70% RH reduced 4.9-6.8, 5.1-5.6, and 4.2-6.3 log CFU/g of STEC, L. monocytogenes, and Salmonella, respectively, on produce, with the highest reductions on baby-cut carrots. For almonds and peppercorns, ClO2(g) treatments under higher RH caused higher reductions. The treatment of 2 mg/L-9 hr or 3 mg/L-4 hr at 95% RH reduced >4.0 log of STEC and Salmonella on almonds, and 1 mg/L-5 hr at 85% RH achieved >5.0 log reductions on peppercorns. Applying moisture to the surfaces of almonds caused >4.0 log reductions using 1 mg/L-5 hr at 95% RH. This study identified effective ClO2(g) treatment parameters for achieving >4.0 log reductions of common pathogens on tomatoes, blueberries, baby-cut carrots, almonds, and peppercorns and showed that ClO2(g) generator is suitable for large-scale decontamination. These findings can be used for pilot-scale ClO2(g) decontamination of these products and for testing using ClO2(g) for commercial-scale decontamination trials.