Impact of Chlorine Dioxide Slow-releasing Preservative on Quality and Key Anthocyanins of Litchi during Low Temperature Storage

Litchi is prone to deterioration in quality after harvest due to degradation of anthocyanins and respiratory metabolism, and chlorine dioxide (ClO₂) has multiple effects on color protection and respiratory inhibition. In this study, 0.1 g (T1), 0.4 g (T2), and 1.2 g (T3) of ClO₂ slow-releasing preservatives were used to treat lychees with 0 g (CK) as the control to evaluate the preservation effect by quality index, color index and anthocyanin, and correlation analysis was applied to explore the association between them. The results showed that the litchi of the T1 showed the optimal qualities. On the 7th day, the total soluble solids and a^* values of litchi in the T1 were significantly (P<0.05) increased by 2.93% and 10.13%, respectively, while the respiration rate was significantly (P<0.05) decreased by 34.54% compared to the CK group in the same period. On the contrary, the relative conductivity of the T3 litchi reached the highest value of 35.84% on the 7th day, and a^* decreased to the lowest value of 18.38, indicating significant damage to cell structure, bleaching, and the worst storage quality. To further investigate the relationship between color changes and anthocyanins, 10 key anthocyanins were selected from litchi, including 7 proanthocyanins, which accounted for 66.96% of the total. The correlation analysis showed that the correlation coefficients between a^* value and cyanidin-3-O-galactoside in the T1, T2, and T3 groups were 0.980, 0.548, and 0.360, respectively, and the correlation coefficients with cyanidin-3-O-glucoside were 0.985, 0.488, and 0.402 during storage. The T1 maintained the best color, possibly due to the slower decomposition of the two key red anthocyanins above, while the T3 accelerated the decomposition of anthocyanins. This study could provide valuable insights for enhancing the postharvest quality of litchi.