贮温对龙眼果肉采后衰老中的抗氧化能力及相关酶的影响

Effects of Storage Temperature on the Oxidation Resistance and Relevant Enzymes During the Postharvest Senescence of Longan Aril

以石硖龙眼Dimocarpus longana Lour. cv. Shixia为试材,研究了不同贮温下3种抗氧化能力(总抗氧化能力TAOC、抑制超氧阴离子能力、抑制羟自由基能力)、相关酶[过氧化物酶(POD)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)]及氧化产物[丙二醛(MDA)、过氧化氢(H2O2)]在龙眼采后果肉衰老过程中的变化规律及相互关系.结果表明:在4和20℃2种贮温下,龙眼果肉均经历了一个不可逆的衰老过程,且高温下的衰老速度远超过低温;氧化产物、3种抗氧化能力和相关酶因贮藏温度不同而出现变化规律和作用水平差异;在较高贮温下,龙眼果肉更易遭受活性氧自由基的伤害,且POD、SOD和CAT对自由基的诱导反应比低温下更加积极.3种抗氧化能力指标在2种贮温下彼此之间均无显著相关性;4℃下,SOD在龙眼果肉低温衰老过程中的抗氧化作用不明显,POD和CAT发挥了主要作用;20℃下,CAT抗氧化作用不明显,而SOD和POD与抑制O2-.能力以及MDA、H2O2含量密切相关,且发挥了主要作用。

The variation and inter-relations between the three kinds of antioxidant capacity （ total oxidation resistance, the capacity to inhibit superoxide anion and hydroxyl radical）, relavant enzymes [ peroxidase （ POD）, superoxide dismntase （ SOD ） and catalase （CAT） ], and the oxidation products [ malonalde-hyde （MDA）and （H202 ）] during the postharvest senescence of longan （cv. Shixia） aril stored at 4℃ and 20℃ were studied. The results showed that the longan aril suffered a process of irreversible senes- cence during the storage at high and low temperatures, and the senescence progress at high temperature far shorter than that at low temperature. The variation and effect levels in the peroxide products, three kinds of antioxidant capacity and relevant enzymes varied with the different storage temperatures. Further-more, longan aril was more subject to the damage from free oxygen radicals at high storage temperature than low temperature, and POD, SOD and CAT were more positive to be induced by free oxygen radicals. The correlation analysis showed that there were no significant differences between the three oxidation resistance. POD and CAT played a more important role than SOD in anti-oxidation during the senescence of longan aril at 4℃, while SOD and POD were closely related to the capacity to inhibit superoxide ani-on, MDA and H202 contents and played a more important role than CAT.