Active Oxygens Generation and the Formation of Scavenging System with Maturation and Senescence in Fruit and Vegetables

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Active oxygens generation and the formation of scavenging system with maturation and senescence in sweet pepper and broccoli were studied.1. The floret yellowing was inhibited in heat-treated (50℃, 2 hrs) broccoli. Hydrogen peroxide content in heat-treated broccoli showed higher level than the control. The activities of the enzymes involved in an ascorbate - glutathione cycle showed higher levels in heat-treated broccoli than those in control. Cytosolic ascorbate peroxidase (cAPX) activity in heat-treated broccoli increased slightly during storage at 15℃. Moreover, the cAPX mRNA level in heat-treated broccoli was detected greatly during storage.2. Superoxide dismutase (SOD) activity in sweet pepper increased from green (G) to yellow/green (Y/G) stage of maturation. A number of Cu, Zn-SOD isozymes increased at green/yellow (G/Y) and Y/G stages. SOD activity was mainly found in cytosol. APX activity increased from G to Y/G stage. A number of cAPX isozymes increased from G/Y to Y/G stage and the activity was present chiefly in the cytosol. The enzyme activities involved in the ascorbate-glutathione cycle showed a change with maturation.