Improved preservation effects of litchi fruit by combining chitosan coating with ascorbic acid treatment during postharvest storage

Pericarp browning and aril decay of litchi fruits shorten post-harvest storage and thus reduce market value. Effects of chitosan coating and ascorbic acid (AsA) on litchi fruits storage were investigated in this paper. Based on the fact that AsA increases anti-oxidation capacity and chitosan inhibits dehydration and microbial attack, the novel strategies of combining chitosan with AsA treatment were developed to improve litchi storability. By treating harvest fruits with 40 mmol/l AsA and 1.0% (w/v) chitosan solution, parameters of browning index and relative leakage rate and activities of polyphenol oxidase (PPO) and peroxidase (POD) in pericarp were markedly lowered in treated fruits. Moreover, increased activities of super oxide dismutase (SOD) and catalase (CAT) and contents of AsA and glutathione were observed in pulp of treated fruit, thus leading to lowered contents of hydrogen peroxide (H2O2) and malondialdehyde (MDA). Correspondingly, total soluble solids, soluble sugar and titratable acidity were significantly increased and thus lowered decay rate was achieved. It was suggested that chitosan and AsA play active roles in inhibiting pericarp browning, dehydration and microbial attack and maintaining membrane integrity, thus improved litchi storability being achieved.