Melatonin and 1-Methylcyclopropene Improve the Postharvest Quality and Antioxidant Capacity of ‘Youhou’ Sweet Persimmons during Cold Storage

ABSTRACT The objective of this study was to identify the effects of 100 μM melatonin (MT), 1 μL/L 1-methylcyclopropene (1-MCP), and their combination treatments on the postharvest characteristics, nutritional quality, and antioxidant capacity of ‘Youhou’ persimmons during cold storage at 0°C. Compared with the control fruit, all three treatments suppressed ethylene production and respiration rate, leading to delayed softening, reduced peel discoloration, and soluble solid content loss. These treatments increased plasma membrane stability by inhibiting lipoxygenase activity and decreasing H2O2, electrolyte leakage, and malondialdehyde concentrations, resulting in higher tolerance to chilling injury (CI). At the end of storage, the CI index of fruit treated with MT, 1-MCP, and MT+1-MCP respectively exhibited 54.67%, 14.57%, and 5.54%, which were significantly lower than the control ones (78.36%). In addition, the phenolics, flavonoids, and ascorbic acid contents were also improved by the above treatments, which contributed to higher antioxidant activity than the control fruit at the late stage of storage. The combination of MT and 1-MCP treatment was more effective in improving the postharvest quality and preserving high antioxidant ability levels than either treatment alone, indicating a promising measure to preserve sweet persimmons up to 70 d.