The efficacy of ozone gas in reducing foodborne pathogens and spoilage microorganisms has been studied on produce, including green peppers, carrots, black peppers, grapes, strawberries, and lettuce (Table 18.5). High concentrations (>1000ppm or 2 mg/l) of gaseous ozone treatments have been shown to be extremely effective in reducing E. coli 0157:H7  and bacillus spores  on filter paper. Han et al.  found that a greater than 5 log reduction (CFU/site) of E. coli 0157:H7 on green pepper surface could be achieved by a continuous ozone gas treatment at 5 mg/l for 25 minutes under > 70% RH and at 22°C. Sarig et al.  reported that microbial counts on grapes were significantly reduced after an 8 mg/l ozone gas treatment for 20 minutes. Zhao and Cranston  treated ground black peppers with 6.7 mg/l ozonized air (6 l/min). They found a greater than 3 log reduction of E. coli and Salmonella spp. after
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