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

Authors: SONG, YUANYUAN - Jiangnan University; Fan, Xuetong

Submitted to: Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2019
Publication Date: 11/23/2019
Citation: Song, Y., Fan, X. 2019. 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. Food Microbiology. https://doi.org/10.1016/j.ijfoodmicro.2017.03.004.
DOI: https://doi.org/10.1016/j.ijfoodmicro.2017.03.004

Interpretive Summary: Controlling and inactivating foodborne pathogenic microorganisms on fresh produce remains a formidable challenge. In the present study, we passed aerosolized hydrogen peroxide through a cold plasma arc to inactivate bacteria on four types of fresh produce items and investigated the interaction of the plasma arc and hydrogen peroxide mist against Salmonella and Listeria. Our results demonstrated that passing hydrogen peroxide mist through a cold plasma arc significantly enhanced the efficacy of hydrogen peroxide against bacteria on fresh produce, resulting in more than 99.99% reduction of Salmonella and Listeria. The information will be of interest to the produce industry which is seeking more effective intervention technologies to enhance the microbial safety of fresh produce.

Technical Abstract: Effective decontamination technologies are urgently needed to enhance the microbial safety of fresh produce. In the present study, we optimized the conditions for the cold plasma-activated aerosolized hydrogen peroxide (H2O2) treatment for the inactivation of Salmonella Typhimurium on four types of fresh produce items and 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 H2O2 with and without cold plasma for various times. On the smooth surfaces of tomatoes and apples, an 8 second treatment followed by 30 minute dwell time achieved more than 5 log CFU/piece reduction of Salmonella. On other fresh produce items, the treatment, when applied for a longer time period, achieved up to a 3.6 log reduction of Salmonella. For all fresh produce items and surfaces, cold plasma significantly (P<0.05) improved the efficacy of aerosolized H2O2 against Salmonella and L. innocua. Without cold plasma activation, H2O2 aerosols only reduced populations of Salmonella by 1.54-3.17 log CFU/piece while H2O2 with cold plasma achieved 2.35-5.50 log CFU/piece reductions of Salmonella. L. innocua was more sensitive to the cold plasma-activated H2O2 than Salmonella. Cold plasma, H2O2 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 H2O2 were only 1.35-3.77 log CFU/piece. Overall, our results demonstrated that cold plasma activation (ionization) significantly enhanced the efficacy of H2O2 mist against bacteria on fresh produce, and the technology may be used to enhance microbial safety.