Abstract Water fennel is vulnerable to a loss in quality during storage. To improve postharvest quality, fresh-cut water fennel was treated with 37.04 mg m-3 ozone for 15 minutes every 5 days, and then stored at 5 °C for 20 days, and the related quality and antioxidant capacity indexes were determined. The results showed that compared with the control group, the ozone-treated water fennel had better sensory quality, color (L*, a*, ΔE, Chroma ) and firmness after 20 days of storage, and the weight loss decreased by 47%, malondialdehyde content decreased by 41%, soluble solids content decreased by 20%.The ozone treatment also effectively inhibited the increase of respiratory rate and phenolic substances during storage of fresh-cut water fennel. Meanwhile, ozone treatment maintained the content of ascorbic acid, inhibited the activity of polyphenol oxidase and induced an increase of peroxidase, catalase, ascorbate peroxidase and superoxide dismutase, but reduced the content of reduced glutathione. Water fennel after ozone treatment maintained the appearance, texture characteristics and high commercial value during storage. Therefore, ozone treatment may be used as an effective preservation technology for postharvest storage and circulation of water fennel.

Abstract Melatonin is known to influence various physiological processes, including plant ripening; however, the effect of melatonin on postharvest blueberry fruit softening is unknown. Herein, the effects of melatonin at different concentrations (100, 300, and 500 μmol L-1) on the quality parameters, cell wall substances, cell-wall-degrading enzymes, and cell wall ultrastructure of blueberry fruits were investigated during low-temperature storage. Melatonin treatment was found to effectively delay the decline in fruit firmness, slow the loss of soluble solids and titratable acids, and decrease the respiration rate and decay rate of blueberry fruits. The blueberry fruits treated with 300 μmol L-1 melatonin exhibited the best quality. Melatonin treatment promoted anthocyanin accumulation, delayed ascorbic acid degradation, maintained a low relative membrane permeability in pulp, inhibited increases in lipoxygenase (LOX) activity, and reduced membrane lipid peroxidation. Moreover, melatonin controlled the formation of soluble pectin by inhibiting the activities of pectin methylesterase (PME), polygalacturonase (PG), cellulase (Cx), and β-glucosidase (β-Glu) while maintaining high contents of protopectin and cellulose. These results indicate that melatonin can effectively improve blueberry fruit quality and antioxidant capacity as well as and delay fruit softening by inhibiting the degradation of cell wall substances.