Abstract: The inhibitory effect of ultraviolet-C (UV-C) treatment on enzymatic browning of fresh-cut apples was investigated and correlated with the metabolism of reactive oxygen species (ROS). Variations in ROS levels, antioxidant enzyme activities, the content of the antioxidant VC and non-enzymatic antioxidant properties were evaluated during the storage of UV-C-treated apples. The results showed that UV-C treatment significantly inhibited surface browning of fresh-cut apples during storage, accompanied by lowering the production rate of superoxide anion radical, and H2O2 and malondialdehyde (MDA) contents. Furthermore, UV-C treatment enhanced the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), increased VC content, slowed down the decrease in non-enzymatic antioxidant properties such as scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals and ferric reducing antioxidant power (FRAP) in fresh-cut apples during storage. Pearson correlation analysis and principal component analysis revealed that browning index (BI) was significantly positively correlated with ROS and MDA levels (P < 0.05) and negatively with enzymatic and nonenzymatic antioxidant activities (P < 0.05, P < 0.01). UV-C treatment improved ROS metabolism of fresh-cut apples as compared to the control. Collectively, these findings suggest that UV-C treatment could enhance ROS metabolism in freshcut apples, thereby alleviating lipid peroxidation and inhibiting surface browning.

Key words: fresh-cut apples, ultraviolet-C, browning, reactive oxygen species metabolism