The effectiveness of closed-circulation gaseous chlorine dioxide or ozone treatment against bacterial pathogens on produce

Abstract

The objective of this study was to examine the effectiveness of gaseous chlorine dioxide (ClO2) or ozone (O3) treatment against Shiga toxin-producing Escherichia coli (STEC), serovars of Salmonella enterica, and Listeria monocytogenes on baby-cut carrots, lowbush blueberries, and beefsteak tomatoes using a scaled-up closed-circulation treatment system. Dry ClO2 precursors were combined in-chamber to make 0.03, 0.06, and 0.12 mg ClO2/g produce for a 2.5 h exposure and 0.04, 0.07, and 0.15 mg ClO2/g produce for a 5.0 h exposure time. Ozone was generated through corona-discharge of a dry oxygen feed and either 0.86 or 1.71 μg O3/g produce concentrations were used to treat 2 kg of produce for 2.5 and 5.0 h.Overall, ClO2 treatment resulted in maximum bacterial reductions of >7 log observed on carrots and tomatoes and 3.7 log on blueberries. Exposure gaseous O3 resulted in observed reductions of 1.2, 1.8, and 1.6 log and simultaneously resulted in noticeable bleaching carrot and tomato tissue as well. These results reported here indicate that gaseous ClO2 can be a suitable treatment when implemented correctly to reduce bacterial pathogens in a storage setting.