Phenyllactic acid maintains the postharvest quality of winter jujube fruit via activating ascorbic acid metabolism

Quality deterioration is the main factor that causes economic losses of winter jujube fruit during logistics. Winter jujube fruit was applied as the material to study the impacts of phenyllactic acid (PLA) dipping on postharvest quality and ascorbic acid (AsA) metabolism during storage at ambient conditions. Results demonstrated that PLA dipping effectively postponed the decline in soluble sugar and chlorophyll contents, as well as the increase of weight loss. Additionally, it significantly reduced malondialdehyde content and preserved the surface color of the fruit. PLA also enhanced the enzymatic activities and gene expressions of L-galactose-1,4-lactone dehydrogenase, L-galactose dehydrogenase, ascorbate peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase, and glutathione reductase in winter jujubes. Conversely, it led to a reduction in ascorbate oxidase activity. Moreover, PLA up-regulated the expressions of ZjGPI, ZjPMI1-like, ZjGMP, and ZjGGP1 involved in AsA synthesis, thereby enhancing the accumulation of AsA and glutathione. All these findings collectively suggest that PLA treatment has the potential to maintain higher quality of winter jujube fruit via stimulating AsA metabolism.