短波紫外线控制鲜切苹果褐变与其活性氧代谢的相关性

为研究短波紫外线（ultraviolet-C，UV-C）处理对鲜切苹果褐变控制与活性氧（reactive oxygen species，ROS）代谢的相关性，分析贮藏过程中UV-C处理后鲜切苹果的ROS水平、抗氧化相关酶活力、抗氧化物质（VC）含量以及非酶抗氧化能力的变化。结果表明：UV-C处理能够有效抑制鲜切苹果的褐变，降低超氧阴离子自由基产生速率和H2O2、丙二醛（malondialdehyde，MDA）含量；同时，UV-C处理能够有效提高抗氧化相关酶（超氧化物歧化酶、过氧化氢酶、抗坏血酸过氧化酶和谷胱甘肽还原酶）活力以及VC含量，减缓鲜切苹果非酶抗氧化能力（1,1-二苯基-2-三硝基苯肼自由基、2,2’-联氮-双(3-乙基苯并噻唑-6-磺酸)阳离子自由基清除能力和还原能力）在贮藏过程中的下降；相关性分析与主成分分析结果显示，鲜切苹果褐变程度与ROS水平和MDA含量呈显著正相关（P＜0.05），与抗氧化酶活力和非酶抗氧化能力呈显著（P＜0.05）或极显著（P＜0.01）负相关，且UV-C处理组鲜切苹果的ROS代谢能力高于对照组。因此，推测UV-C处理可能通过调节鲜切苹果的ROS代谢进而控制其贮藏过程中的褐变。

Correlation between Enzymatic Browning Inhibition by UV-C Treatment and Reactive Oxygen Species Metabolism of Fresh-Cut Apples

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.