Effects of chitosan grafted with gallic acid treatment on the postharvest physiology and biochemistry of Saimaiti apricots

Traditional cold storage methods may not adequately preserve the flavor of apricot fruit, impacting its overall edible quality. Chitosan-gallic acid derivative membranes can address the insufficient antioxidant and antibacterial properties of chitosan alone, thereby better preserving the aroma of apricots. In this study, Xinjiang Saimaiti apricots were treated with chitosan (CS, 0.5% and 1%) and CS grafted with gallic acid (GA-g-CS, 0.5% and 1%) during storage at 1 °C ± 0.5 °C. The effects of GA-g-CS treatment on postharvest physiology, aromatic volatile content, amino acid content, and fatty acid content of apricots were analyzed. These results showed that 1% GA-g-CS derivatives effectively maintained fruit firmness, soluble solid content (SSC), and titratable acid (TA); postponed the rise in weight loss, fell in respiratory rate, and inhibited the release of ethylene. GA-g-CS derivatives could restrain the accumulation of malondialdehyde (MDA) and increase the relative electrical conductivity. The results demonstrated that reducing polyphenol oxidase (PPO) activity and improving peroxidase (POD) activity could delay fruit browning and aging. The application of 1% GA-g-CS effectively preserved the levels of esters and ketones in Saimaiti apricots throughout the storage period. Moreover, it decelerated the decline in aldehyde content and efficiently decreased the production of ethanol during storage. The correlation analysis revealed significant positive correlations between aspartate, alanine, linoleic acid, and α-linolenic acid and the main aroma components. Conversely, stearic acid exhibited a significant negative correlation with the main aroma components. To sum up, chitosan-gallic acid derivatives can be used as a new type of edible film for fruit and vegetable preservation. And it can extend the shelf life of Saimaiti apricots by 12 days, compared to traditional refrigeration.