Application of underwater dielectric barrier discharge as a washing method for reduction of Salmonella Typhimurium on perilla leaves

• Underwater DBD was used as an alternative washing method for fresh produce.
• Suspended S. Typhimurium was effectively inactivated by underwater DBD treatment.
• Reduction level on perilla leaf by underwater DBD was comparable to chlorine washing.

To develop an alternative washing method for sanitizing fresh produce, a submerged plasma reactor of dielectric barrier discharge (underwater DBD) was evaluated. Salmonella Typhimurium in suspension was reduced by 4.3 log after underwater DBD treatment for 1 min. Membrane damage was apparent in S. Typhimurium that was exposed to underwater DBD based on scanning electron microscopic analysis. DNA electrophoresis analysis revealed that the amount of genomic DNA that was purified from S. Typhimurium cells decreased after underwater DBD treatment. These results suggest that DNA might be released from the cytoplasm due to the membrane damage induced by underwater DBD treatment. The reduction of S. Typhimurium-inoculated perilla leaf was 2.5 log after the underwater DBD treatment, which was similar to chlorine washing (100 ppm). The color parameters did not show significant changes after underwater DBD treatment (p > 0.05). In conclusion, underwater DBD could potentially be used as a washing method to reduce the amount of pathogenic bacteria on fresh produce.