臭氧精准处理提高采后草莓抗氧化酶活性和酚类物质含量

臭氧处理被认为是一种有效而无污染的贮藏保鲜方式,而臭氧的强氧化性也被认为对于采后果蔬的活性氧清除系统存在影响。该研究以天津市种植最广泛的"京桃香"草莓为试材,探讨了不同浓度的臭氧(0、2.144、6.432、10.72、15.008 mg/m~3)处理对草莓采后活性氧起抑制作用的非酶促、酶促清除系统的影响。总酚(total phenols,TPC)、总类黄酮(total flavonoids,TFC)和抗坏血酸(ascorbic acid,ASA)为非酶促抗氧化关键代谢物指标,以超氧化物歧化酶(superoxide dismutase,SOD)、过氧化物酶(peroxidase,POD)和抗坏血酸超氧化物酶(ascorbic acid superoxidase,APX)为关键酶活指标进行检测。结果表明,整个贮藏期间,对于非酶促清除系统,采后草莓总酚类物质在2.144、6.432、15.008 mg/m~3的臭氧处理组具有一定的累积效果,但低于对照组的含量;黄酮类物质在2.144、15.008 mg/m~3处理组中的含量不断下降,而6.432mg/m~3处理组中的含量为先下降后上升,但3个处理组中的含量均低于对照组;ASA含量在对照组中的变化不大,但在2.144、6.432、15.008 mg/m~3处理组中不断减少,且15.008 mg/m~3的臭氧处理组的下降幅度最大。而相较于对照组和其他3个不同浓度的臭氧处理组,10.72 mg/m~3的O_3处理能够显著促进酚类化合物和抗坏血酸的生成,维持总黄酮含量在较高水平。对于酶促清除系统,高浓度的O_3处理能够快速诱导草莓果实POD活性的升高。但是随着贮藏时间的延长,15.008mg/m~3处理组迅速出现降低的变化趋势。相较于对照组,2.144 mg/m~3浓度O_3处理组的酶活变化不大,但6.432 mg/m~3处理组却存在一定的抑制作用。10.72 mg/m~3的O_3处理能够显著提升SOD活性(P﹤0.05),使其最大值提前,能够提升APX活性,刺激POD酶活的活性提高,并推迟POD活性出现高峰的时间。总体来说,10.72 mg/m~3浓度的臭氧处理能够增强采后草莓氧化还原系统相关酶促反应酶活,促进非酶促反应抗氧化物质的生成,对于采后草莓的抗氧化物质积累具有积极作用,有利于提高草莓的食用价值和经济价值。

Ozone treatment improving antioxidant enzyme activity and phenolic content of postharvest strawberry

Abstract: Ozone treatment is considered as an effective and non-polluting method of storage and preservation, and the strong oxidizing effect of ozone is also considered to have an effect on the active oxygen scavenging system of harvested fruits and vegetables. The inhibition of reactive oxygen species of non-enzymatic, enzymatic scavenging system of post-harvest ''Jing Tao Xiang'' strawberry, which are wide-planted in Tianjin, treated with different ozone concentrations (0, 2.144, 6.432, 10.72 and 15.008 mg/m3) was investigated in this study. Post-harvest strawberries were treated for 5 h every 7 days in an ozone preservation device independently developed by the National Preservation Engineering Technology Research Center (Tianjin), and then quickly transferred to a 0 °C cold storage. Total phenols content (TPC), total flavonoids content (TFC), and ascorbic acid (ASA) were detected as key non-enzymatic antioxidants, while superoxidase (SOD), peroxidase (POD), and ascorbate peroxidase (APX) were detected as key enzymes in the enzymatic antioxidant system. Results showed that for non-enzymatic antioxidant system, the total phenolics of post-harvest strawberry in the ozone treatment group of 2.144, 6.432 and 15.008 mg/m3 had a certain accumulation during the whole storage period, but lower than the control group. The content of flavonoids in the 2.144 and 15.008 mg/m3 treatment groups decreased continuously throughout the storage period, while the content in the 6.432 mg/m3 treatment group decreased and then increased, but the contents in the three treatment groups were lower than the control group; the ASA content did not change much in the control group, but decreased continuously in the 2.144, 6.432 and 15.008 mg/m3 treatment groups, and the 15.008 mg/m3 ozone treatment group had the largest decline. Compared with the control group and other three different concentrations of ozone treatment group. However, 10.72 mg/m3 ozone treatment significantly promoted the formation of phenolic compounds and ascorbic acid, maintained the total flavonoid content at a higher level, and which was conducive to the formation and accumulation of non-enzymatic antioxidant nutrients. For the enzymatic antioxidant system, high concentrations of O3 treatment rapidly induced an increase in POD activity in strawberry fruit. However, as the storage time prolonged, the decreasing trend appeared rapidly in the 15.008 mg/m3 treatment group. Compared with the control group, the enzyme activity of the 2.144 mg/m3 concentration O3 treatment group did not change much, but the enzyme activity of the 6.432 mg/m3 treatment group was inhibited. However, the SOD activity of 10.72 mg/m3 ozone treatment group was significantly increased (P<0.05), and the maximum value was advanced, the activity of APX was also enhanced. The activity of POD enzyme activity of 10.72 mg/m3 O3 treatment group was stimulated, and the peak of POD activity was delayed. Overall, ozone treatment at a concentration of 10.72 mg/m3 could enhance the enzymatic reaction activity of the redox system of postharvest strawberry and increase the content of non-enzymatic reaction substances, which had a positive effect on the accumulation of antioxidants in postharvest strawberries and was conducive to improving the edible value and economic value of post-harvest strawberries.