Physiological and Metabolic Analysis of Winter Jujube after Postharvest Treatment with Calcium Chloride and a Composite Film

Background: Zizyphus jujube Miller cv. Dongzao is extremely susceptible to reddening, browning, nutritional loss and perishability after harvest. In this study, we evaluated the mechanisms of calcium chloride and chitosan/nano-silica composite film treatments on the quality, especially in reddening by physiological and metabolomic assays.

Results: The treatment delayed the decline of phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), and chalcone isomerase (CHI) activities. Meanwhile, the treated groups retarded the increases in anthocyanin and quercetin contents by inhibiting the gene expressions of flavonol synthase (FaFLS), dihydroflavonol 4-reductase (FaDFR) and anthocyanidin synthase (FaANS), while promoting leucoanthocyanidin reductase (FaLAR) expression, which leads to retardation of fruit reddening. Anthocyanins were found to be responsible for post-harvest winter jujube reddening through principal component analysis (PCA). Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) results indicated that the treated group delayed the decline of the quality of Dongzao and extended its shelf life.

Conclusion: The treatment induced the heightening of flavonoids metabolism. They enhanced the nutritional value and the ability to resist stress by delaying the decline of PAL, CHS, and CHI activities. Meanwhile, the treated groups retarded the increase in anthocyanin and quercetin contents by inhibiting the gene expressions of FaFLS, FaDFR and FaANS and promoting FaLAR expression, which leads to retardation of fruit reddening. Anthocyanins is to be responsible for post-harvest winter jujube reddening. Coating treatment effectively delayed the decline of winter jujube quality. This article is protected by copyright. All rights reserved.

Keywords: coating film; enzyme activity; flavonoid pathway; gene expression; quality; winter jujube.