Effects of Sodium Dehydroacetate Treatment on Delaying Postharvest Browning and Enhancing Antioxidant Activity of Litchi

This study aimed to explore the regulatory effect of sodium dehydroacetate (SD) on the quality, browning, and antioxidant activity of litchi during postharvest storage. ‘Guiwei’ litchi fruits were treated with 0.5 g/L SD solution and subsequently stored at (25 ± 1) ℃ for 7 days. Changes in quality attributes, browning degree and antioxidant parameters were evaluated during the storage period. The results indicated that the 0.5 g/L SD treatment effectively maintained the postharvest quality of litchi, delayed the decrease in peel color parameters (L*, a*, and b* values), suppressed the increase in decay incidence and the relative electrical conductivity of the peel during the late storage stage (P < 0.05), lowered the respiratory peak, and significantly mitigated the decline in total soluble solid (TSS), soluble sugar and VC contents. Moreover, the SD treatment markedly inhibited pericarp browning, resulting in a 45.66% decrease in browning index after 7 days of storage compared with the control group (P < 0.001). This treatment also delayed the degradation of total anthocyanins and significantly inhibited the activities of polyphenol oxidase (PPO) and laccase (LAC). Furthermore, the 0.5 g/L SD treatment significantly enhanced the antioxidant capacity of litchi by inhibiting the accumulation of reactive oxygen species (ROS) metabolites such as malondialdehyde (MDA), hydrogen peroxide (H₂O₂) and superoxide anion radical. It also significantly alleviated the decrease in total phenols and flavonoids during the late storage stage (P < 0.05). Throughout the storage period, the activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) remained consistently higher than those in the control group. In conclusion, the 0.5 g/L SD treatment effectively delays the postharvest senescence of litchi by preserving the storage quality, suppressing browning, and enhancing the antioxidant capacity. These findings provide a theoretical basis and practical reference for optimizing postharvest preservation techniques for litchi.