Effects of melatonin treatment on the enzymatic browning and nutritional quality of fresh-cut pear fruit

•Surface browning, the contents of MDA and H2O2 were reduced by melatonin treatment.•Melatonin inhibited the growth of microorganism and delayed the ascorbic acid loss.•Melatonin increased total phenolic content and antioxidant capacity.•Melatonin increased PAL and CHS activities and decreased the PPO activity.•Melatonin down-regulated the expression of genes participating in enzymatic browning. The effects of exogenous melatonin treatment on the enzymatic browning and nutritional quality of fresh-cut pear fruit were investigated. Fresh-cut fruit soaked with 0, 0.05, 0.1 and 0.5 mM melatonin were stored at 4 °C. Our results showed that 0.1 mM melatonin treatment was optimal for reducing the surface browning and maintaining the titratable acidity of the fresh-cut fruit, which significantly decreased MDA and H2O2 contents and the growth of microorganism, enhanced total phenolic content and antioxidant capacity, and delayed the reduction of ascorbic acid. Furthermore, melatonin treatment at 0.1 mM decreased the expression of genes involving in enzymatic browning pathway including POD, PPO1, PPO5 and LOX1, and reduced PPO activity. Moreover, this treatment increased the expression of PAL and CHS, and enhanced PAL and CHS activities. These results showed that melatonin treatment might be a promising strategy to alleviate browning and improve the nutritional quality of fresh-cut pear fruit.