Sterilization effect and mechanism exploration of a mode-combination method on Staphylococcus aureus in thick ice layers in a large sealed freezer

Cold-chain transport is a crucial cross-regional transmission pathway for severe acute respiratory syndrome coronavirus 2 and other microorganisms. In this study, the mode-combination method is adopted for sterilization in a 1.138 m³ freezer by mixing effluent gases of NO_x and O₃ mode air discharges. The mixed gas can effectively inactivate Staphylococcus aureus in 10 mm ice within 3 h, which significantly surpasses O₃ gas. Moreover, the inactivation effect of the mixed gas can penetrate deep into ice, contrasting with the surface effect of O₃ gas. This disparity is linked to the difference in penetration depth of strong oxidizing long-lived reactive species. This study validates the sterilization efficacy of cold atmospheric plasma in practical cold-chain environment, critical for curbing infectious disease transmission.