Hydrogen peroxide (H 2 O 2 ) has long been studied as an aqueous sanitizer to enhance microbial safety of fresh produce. Recently, we demonstrated that cold plasma-activated H 2 O 2 aerosols, hereafter referred to as ionized hydrogen peroxide (iHP), reduced populations of Salmonella, Listeria, and E. coli by up to 5.5 logs on surfaces of various produce items. However, the amount and fate of H 2 O 2 residue left on fresh produce after treatments have not been evaluated. In the present study, H 2 O 2 residue levels on apples, tomatoes, cantaloupe, and Romaine lettuce were analyzed after treatments with 7.8% iHP at conditions that had been optimized and tailored for Salmonella reductions and each produce items. Results showed that higher residue levels were found on lettuce than on cantaloupes, tomatoes and apples immediately after treatments. During storage at 10 and 22°C, H 2 O 2 levels decreased rapidly and fell below <1 mg/kg within 1 day after treatments for all fresh produce items. Furthermore, the decrease was faster at 22°C than at 10°C. Most importantly, the levels of H 2 O 2 residue on the fresh produce items were lower than those after wash with 1% H 2 O 2 for 1 min. Overall, our results demonstrated that levels of H 2 O 2 residue on fresh produce surfaces decomposed rapidly after treatment with iHP and did not appear to pose a safety concern after 1 day of storage.
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
