Cold plasma enhances the efficacy of aerosolized hydrogen peroxide in reducing populations of Salmonella Typhimurium and Listeria innocua on grape tomatoes, apples, cantaloupe and romaine lettuce

摘要

In the present study, we investigated whether cold plasma activation affected the efficacy of aerosolized hydrogen peroxide against S. Typhimurium and L. innocua. Stem scars and smooth surfaces of grape tomatoes, surfaces of Granny Smith apples and Romaine lettuce (both midrib and upper leaves) and cantaloupe rinds were inoculated with two-strain cocktails of S. Typhimurium and 3-strain cocktails of L. innocua. The inoculated samples were treated with 7.8% aerosolized H_2O_2 with and without cold plasma for various times. For all fresh produce items and surfaces, cold plasma significandy (P < 0.05) improved the efficacy of aerosolized H_2O_2 against Salmonella and L. innocua. Without cold plasma activation, H_2O_2 aerosols only reduced populations of Salmonella by 1.54-3.17 log CFU/piece while H_2O_2 with cold plasma achieved 2.35-5.50 log CFU/piece reductions of Salmonella. L innocua was more sensitive to the cold plasma-activated H_2O_2 than Salmonella. Cold plasma activated H_2O_2 aerosols reduced Listeria populations by more than 5 log CFU/piece on all types and surfaces of fresh produce except for the tomato stem scar area. Without cold plasma, the reductions by H_2O_2 were only 1.35-3.77 log CFU/piece. Overall, our results demonstrated that cold plasma activation significantly enhanced the efficacy of H_2O_2 mist against bacteria on fresh produce.