Evaluation of chlorine dioxide gas against 4 salmonella enterica serovars artificially contaminated on whole blueberries

Authors: Annous, Bassam; Buckley, David; Burke, Angela - Mattrazzo

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary: Fresh produce, such as blueberries, continues to be a source of foodborne illness in the United States. Despite new practices and intervention technologies, blueberries and other produce are contaminated with foodborne pathogens, such as Salmonella spp. The Food and Drug Administration-approved chlorine dioxide gas treatments have been shown to be efficacious against Salmonella spp. and other foodborne pathogens on produce. The application of this gas to high-risk fresh produce provides several benefits, e.g. reduced water use and potential cross contamination with recycled wash-water. Given these challenges and chlorine dioxide gas’ potential, we sought to evaluate the efficacy of this gas against a highly prevalent foodborne pathogen, Salmonella spp., on an understudied fruit: whole fresh blueberries. Chlorine dioxide gas treatments reduced the pathogenic populations on blueberries in excess of 99.999%. These results indicate that this treatment could be a viable process to eliminate human pathogenic Salmonella on blueberries under a variety of relevant conditions. These findings will assist the blueberry industry in utilizing a viable process to eliminate pathogens, thereby decreasing the incidence of illness outbreaks.

Technical Abstract: Fresh produce, such as blueberries, continues to be a source of foodborne illness in the United States. Despite new practices and intervention technologies, blueberries and other produce are contaminated with foodborne pathogens, such as Salmonella spp. The aim of this study was to evaluate the efficacy of chlorine dioxide gas (CDG) against Salmonella enterica serovars Newport, Stanley, Muenchen, and Anatum artificially contaminated on whole fresh blueberries. Blueberries were dip inoculated into a 400 ml bath containing either ca. 6 or 9 log10 CFU/ml of a Salmonella serovar cocktail. Samples were dried for either 2 or 24 h before being treated with 1.5 or 3 mg CDG/L air to a final treatment of 3.55 to 6 ppm-h/g blueberry. Salmonella cells were recovered by stomaching, CDG-treated and non-treated control samples, with 0.1% peptone, and enumerated on xylose-lysine-Tergitol-4 agar. CDG treatments achieved up to a 5.63 log10 CFU/g reduction of the cocktail using 5.5 ppm-h/g while the least efficacious treatment, 4 ppm-h/g (1.5 mg/L), was still capable of a 4.45 log10 CFU/g reduction. Incubation time significantly (p < 0.001) impacted CDG efficacy against both inoculation concentrations. Additionally, all serovars responded similarly to CDG treatment when tested independently (p > 0.0691). Finally, the availability of a water reservoir during treatments did not have significant impact (p = 0.9818) on CDG efficacy in this study. Our results demonstrated that CDG can be an efficacious treatment option for whole blueberry decontamination.