Reduction of pesticides and bacteria on Napa cabbage by ozone microbubble water

Pesticide residues and microorganisms are major concerns when it comes to vegetable safety. Several techniques are employed to eliminate these contaminants, one of which is ozone microbubble water (OMB), known for its effectiveness. However, previous studies on OMB tested OMB's effectiveness on pesticides and microorganisms separately, using different operative parameters for each. Therefore, this study aimed to investigate the efficacy of OMB in removing frequently detected pesticides in Taiwan, namely chlorantraniliprole and dimethomorph, and Salmonella Typhimurium and Escherichia coli. Napa cabbages (Brassica rapa subsp. pekinensis) were inoculated with these contaminants and subjected to OMB treatment (10 min of microbubble activation and 3 min of washing). The control groups included unwashed, municipal water, ozone treatment, microbubble treatment, and sodium hypochlorite washing. The concentrations of residual chlorantraniliprole and dimethomorph after OMB treatment were found to be 16.10% and 19.39%, respectively, of those washed with municipal water. Treatments with only ozone or microbubble showed higher residual concentrations (40.89% and 22.19% for chlorantraniliprole, and 59.37% and 35.47% for dimethomorph, respectively). Using water washing as the baseline, OMB reduced S. Typhimurium and E. coli by 2.11 and 2.31 log CFU g⁻¹, respectively, whereas the reduction achieved by ozone or microbubble treatments alone was lower (∼1 log CFU g⁻¹). Finally, there were no significant differences in the physical characteristics of the leaves (breaking force, cutting force, and color) between OMB and water washing. This study is the first to demonstrate the effective removal of pesticides and bacteria using OMB with the same operative parameters.