ABSTRACT

Hydrogen peroxide (H2O2) has long been studied as an aqueous sanitizer to enhance microbial safety of fresh produce. Recently, we demonstrated that cold plasma–activated H2O2 aerosols, hereafter called ionized hydrogen peroxide (iHP), reduced populations of Salmonella, Listeria, and Escherichia coli by up to 5.5 log on surfaces of various produce items. However, the amount and fate of H2O2 residue left on fresh produce after treatments have not been evaluated. In the present study, H2O2 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 item. Results showed that higher residue levels were found on lettuce than on cantaloupe, tomatoes, and apples immediately after treatments. During storage at 10 and 22°C, H2O2 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 H2O2 residue on the fresh produce items were lower than those after wash with 1% H2O2 for 1 min. Overall, our results demonstrated that levels of H2O2 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.

HIGHLIGHTS
  • Apples, tomatoes, lettuce, and cantaloupe were treated with cold plasma–activated H2O2.

  • The highest level of H2O2 residue was detected on cut lettuce.

  • H2O2 levels decreased rapidly after treatment and depended on temperature.

  • Levels of H2O2 residue after iHP treatment were lower those after washing with 1% H2O2.

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