UV treatment improved the quality of postharvest fruits and vegetables by inducing resistance

Significant product losses of fresh fruits and vegetables occur in the postharvest storage due to rapid senescence and diseases. The traditional postharvest preservation technology is mostly based on cooling and chemical preservation technology. As a residue-free physical sterilization and preservation method, UV treatment has recently been applied to the field of postharvest storage of fruits and vegetables by numerous scientists. This article reviews recent applications of UV-A, -B and –C in postharvest storage of fruits and vegetables, including the effect on disease occurrence, phenolic metabolism and important quality indicators, finds that UV treatment as an acceptable abiotic stress can induce plants to produce defense systems to activate the signalling molecules in advance of the host, including ROS, polyamines, ABA, ethylene, etc, this directly leads to an increase in the resistance of fruits and vegetables to diseases, senescence, and chilling injury during storage. This review mainly focuses on the relationship between fruit antifungal properties induced by UV treatment and changes in the ultrastructure of the cell wall, and summarises the effect of UV treatment on ethylene production, respiration rate, firmness, chlorophyll metabolism, enzymatic antioxidant system and non-enzymatic antioxidant system. Particular findings are that the initial fluctuating effect of UV-B treatment on the metabolism of phenolic substances in fruits and vegetables is mainly caused by flavonoids, not non-flavonoids and that flavonoids are the major substances involved in the defence systems of fruits and vegetables when they are exposed to UV stresses.