General Efficacy Data

The efficacy of gaseous chlorine dioxide to reduce parasite and bacterial burden in produce was studied. Basil and lettuce leaves were inoculated with Cryptosporidium parvum and Cyclospora cayetanensis oocysts, Encephalitozoon intestinalis spores, and a cocktail of two isolates of nalidixic acid–resistant Escherichia coli O157:H7. The inoculated samples were then treated for 20 min with gaseous chlorine dioxide at 4.1 mg/liter. Cryptosporidium had a 2.6 and 3.31 most-probable-number log reduction in basil and lettuce, respectively. Reduction of Encephalitozoon in basil and lettuce was 3.58 and 4.58 CFU/g respectively. E. coli loads were significantly reduced (2.45 to 3.97 log), whereas Cyclospora sporulation was not affected by this treatment.

Regular and excessive rates of chlorine dioxide (ClO2) and hydrogen dioxide (H2O2) were sprayed five times at 3-day intervals on eight bedding plant and nine shrub species to determine if plant damage would result. Marketability was judged to be reduced if >4% surface area of leaves and/or flowers were adversely affected. Rates of 5 and 50 ppm ClO2 and 900 and 2700 ppm H2O2 did not damage most plants tested and will likely control most common pathogen propagules. Rates of 100 ppm ClO2 and 5400 ppm H2O2 did not damage most plants tested if sprayed less than four consecutive times and should control some of the more chemical-tolerant pathogens.

Regular and excessive rates of chlorine dioxide (ClO2) and hydrogen dioxide (H2O2) were sprayed five times at 3-day intervals on eight bedding plant and nine shrub species to determine if plant damage would result. Marketability was judged to be reduced if >4% surface area of leaves and/or flowers were adversely affected. Rates of 5 and 50 ppm ClO2 and 900 and 2700 ppm H2O2 did not damage most plants tested and will likely control most common pathogen propagules. Rates of 100 ppm ClO2 and 5400 ppm H2O2 did not damage most plants tested if sprayed less than four consecutive times and should control some of the more chemical-tolerant pathogens.

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 scaledup 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 mg O3/g produce concentrations were used to treat 2 kg of produce for 2.5 and 5.0 h.