Cold Plasma-activated hydrogen peroxide aerosol inactivates Escherichia coli 0157:H7, Salmonella Typhimurium, and Listeria innocua and maintains quality of grape tomato, spinach and cantaloupe

Authors: JIANG, YUNBIN - Tianjin University Of Science And Technology; Sokorai, Kimberly; PYRGIOTAKIS, GEORGIOS - Harvard University; DEMOKRITOU, PHILIP - Harvard University; LI, XIHONG - Tianjin University Of Science And Technology; Jin, Zhonglin; Mukhopadhyay, Sudarsan; Fan, Xuetong

Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2017
Publication Date: 3/10/2017
Citation: Jiang, Y., Sokorai, K.J., Pyrgiotakis, G., Demokritou, P., Li, X., Jin, Z.T., Mukhopadhyay, S., Fan, X. 2017. Cold Plasma-activated hydrogen peroxide aerosol inactivates Escherichia coli 0157:H7, Salmonella Typhimurium, and Listeria innocua and maintains quality of grape tomato, spinach and cantaloupe. International Journal of Food Microbiology. 249:53-60.

Interpretive Summary: Microbial safety of fresh produce continues to be a concern for producers, processors, and consumers. Currently used methods of sanitizing produce surfaces with aqueous chemicals have limited effectiveness. In this study, we applied hydrogen peroxide, in the form of aerosol activated by high electric field, to inactivate E. coli, Salmonella and Listeria inoculated onto spinach leaves, tomato, and cantaloupe. Result showed that populations of the bacteria on the surfaces of the fresh produce items could be reduced by more than 99.99% depending on types of inoculated bacteria and produce items. The technology represents a novel method to enhance microbial safety of fresh produce.

Technical Abstract: The purpose of this study was to investigate the efficacy of aerosolized hydrogen peroxide in inactivating bacteria and maintaining quality of grape tomato, baby spinach leaves and cantaloupe. Stem scar and smooth surfaces of tomatoes, spinach leaves, and cantaloupe rinds, inoculated with Escherichia coli O157:H7, Salmonella Typhimurium and Listeria innocua, were treated for 45 sec followed by additional 30 min dwell time with hydrogen peroxide (7.8%) aerosols activated by atmospheric cold plasma. Non-inoculated samples were used to study the effects on quality and native microflora populations. Results showed that two ranges of hydrogen peroxide droplets with mean diameters of 40 nm and 3.0 um were introduced into the treatment chamber. The aerosolized hydrogen peroxide treatment reduced populations of the three bacteria on the smooth surface of tomatoes to non-detectable levels (detection limit 0.6 log CFU/fruit). However, on the stem scar area of tomatoes, the reductions of E. coli O157:H7, S. Typhimurium, and L. innocua were only 1.0, 1.4, and 1.2 logs, respectively. On the cantaloupe rind, the treatment reduced populations of E. coli O157:H7, S. Typhimurium and L. innocua by 4.9, 1.3, and 3.0 logs CFU/piece, respectively. Under the same conditions, reductions achieved on spinach leaves were 1.5, 4.2 and 4.0 logs for E. coli O157:H7, S. Typhimurium and L. innocua, respectively. The treatments also significantly reduced populations of native aerobic plate count, and yeasts and mold of tomato fruits and spinach leaves. Furthermore, firmness and color of the samples were not significantly affected by the aerosolized hydrogen peroxide. Overall, our results showed that the efficacy of aerosolized hydrogen peroxide depended on types of inoculated bacteria and produce items, and aerosolized hydrogen peroxide could potentially be used to sanitize fresh fruits and vegetables.