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

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 dismutase （SOD）and catalase （CAT）］, and the oxidation products ［malonaldehyde （MDA）and （H₂O₂）］ 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 senescence 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. Furthermore, 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 anion, MDA and H₂O₂ contents and played a more important role than CAT.