Regulatory Effects of Nitric Oxide Hypobaric Fumigation on Cold Storage Quality and Antioxidant Capacity in Postharvest Flat Peaches

To investigate the regulatory effects of different concentrations of nitric oxide (NO) hypobaric fumigation on postharvest cold storage quality and antioxidant capacity of flat peaches, this study used flat peaches as experimental material. After pre-cooling to a core temperature of 6±1 ℃, the fruits were treated using a laboratory-developed hypobaric fumigation preservation system. The control group (CK) received no treatment, while experimental groups were fumigated with 30, 60, and 90 µL/L NO for 2 hours under 3 kPa pressure. The effects on quality parameters and antioxidant-related indicators during cold storage were evaluated. Results demonstrated that NO hypobaric fumigation effectively maintained fruit firmness, soluble solid content (SSC), and ascorbic acid (AsA) content, reduced weight loss and decay rates, and delayed the respiratory peak by 6 days. After 48 days of storage, the decay rates in the 30, 60, and 90 µL/L NO treatment groups were 8.3%, 11.7%, and 6.7% lowered than the control group, respectively. Furthermore, the 60 µL/L NO treatment significantly inhibited polyphenol oxidase (PPO) activity while enhancing the activities of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT), thereby effectively suppressing the superoxide anion (O₂·⁻) production rate and hydrogen peroxide (H₂O₂) accumulation. At day 36 of storage, the superoxide anion (O₂·⁻) production rate and hydrogen peroxide (H₂O₂) accumulation in the 60 μL/L NO hypobaric fumigation treatment group were 46.28% and 21.05% lower than those in the control group, respectively. At the end of the storage period, the cell membrane permeability and malondialdehyde (MDA) content in the 60 µL/L NO treatment group were 24.56% and 25.25% lowered than the control group, respectively. In conclusion, 60 µL/L NO hypobaric fumigation can activate the endogenous antioxidant enzyme system in flat peaches, inhibit membrane lipid peroxidation, delay the postharvest ripening and senescence processes, and extend the refrigerated shelf life.