Post-harvest Quality Changes in Lettuce Treated with Plasma-activated Water via Spraying and Soaking

Abstract:

At present, research on the post-harvest quality of fruit and vegetables treated with plasma-activated water (PAW) focuses mainly on soaking treatments, with little attention paid to spray treatments. In this study, lettuce was soaked in or sprayed with PAW, and post-treatment changes in the surface total microbial count, weight loss rate, color, chlorophyll content, and metabolites in the lettuce were investigated. The results show that the total microbial counts on the lettuce surface were significantly reduced by 1.54 and 2.82 log CFU/g, respectively, after PAW spraying and soaking (P<0.05). Furthermore, PAW spraying had a less substantial effect on the weight loss rate and chlorophyll content. Metabolomics analysis indicated that a higher flavonoid content was maintained in the lettuce sprayed with PAW than that in the control group. Compared to the control group, the lettuce soaked in PAW showed more active membrane lipid metabolism. In summary, PAW spraying effectively reduced the microbial count on lettuce in the early stage of storage and maintained lettuce quality during storage.