Effectiveness of Aqueous Chlorine Dioxide in Minimizing Food Safety Risk Associated with Salmonella, E. coli O157:H7, and Listeria monocytogenes on Sweet Potatoes

Sodium hypochlorite (NaOCl) is a commonly used sanitizer in the produce industry despite its limited effectiveness against contaminated human pathogens in fresh produce. Aqueous chlorine dioxide (ClO(2)) is an alternative sanitizer offering a greater oxidizing potency with greater efficacy in reducing a large number of microorganisms. We investigated the effect of aqueous chlorine dioxide treatment against human pathogens, Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes seeded on sweet potatoes. Sweet potatoes were spot inoculated (4.2 to 5.7 log CFU/cm(2)) with multi-strain cocktails of Salmonella spp., E. coli O157:H7, and L. monocytogenes and treated for 10–30 min with 5 ppm aqueous ClO(2) or water. Aqueous ClO(2) treatment was significantly (p < 0.05) effective in reducing Salmonella with a reduction of 2.14 log CFU/cm(2) within 20 min compared to 1.44 log CFU/cm(2) for water treatment. Similar results were observed for L. monocytogenes with a 1.98 log CFU/cm(2) reduction compared to 0.49 log CFU/cm(2) reduction observed after 30 min treatment with aqueous ClO(2) the water respectively. The maximum reduction in E. coli O157: H7 reached 2.1 Log CFU/cm(2) after 20 min of treatment with aqueous ClO(2). The level of the pathogens in ClO(2) wash solutions, after the treatment, was below the detectable limit. While in the water wash solutions, the pathogens’ populations ranged from 3.47 to 4.63 log CFU/mL. Our study indicates that aqueous ClO(2) is highly effective in controlling cross-contamination during postharvest washing of sweet potatoes.