Purpose: The purpose of this study was to investigate the efficacy of aerosolized hydrogen peroxide in inactivating bacteria, while maintaining the quality of grape tomato, baby spinach leaves, and cantaloupe.
Methods: 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 s followed by an additional 30 min dwell time with hydrogen peroxide (7.8%) aerosols activated by atmospheric cold plasma. Populations of surviving bacteria were recovered and enumerated.
Results: Two sizes of hydrogen peroxide droplets (mean diameters of 40 nm and 3.0 mm) were produced. The treatment reduced populations of the three bacteria on the smooth surface of tomatoes to nondetectable levels (detection limit 0.6 log CFU/fruit). However, on the stem scar area of tomatoes, the reductions of E. coli O157:H7, Salmonella 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, Salmonella 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, Salmonella Typhimurium, and L. innocua, respectively. The treatment, also, significantly (P<0.05) reduced populations of native aerobic plate count and yeasts and mold on tomato fruits and spinach leaves. Furthermore, firmness and color of the samples were not significantly (P>0.05) affected by the treatment.
Significance: Our results showed that the efficacy of aerosolized hydrogen peroxide depended on types of inoculated bacteria and produce. This technology could potentially be used to sanitize fresh fruits and vegetables.