Effects of Wound Stress by Slicing Sweet Pepper Fruits on Ascorbic Acid Metabolism

Abstract

The effects of wound stress by slicing sweet pepper fruits 'Golden Bell' on ascorbic acid metabolism were invesetiged.
1. The ascorbic acid contents in sliced tissue of mature green and ripe yellow pepper fruits stored at 20 °C were not changed by wounding; although the dehydroascorbic acid contents increased after wounding, that level was maintained constant during the subsequent storage period.
2. The level of hydrogen peroxide in sliced tissues stored at 20 °C was slightly lower than that of whole fruit; thereafter the hydrogen peroxide content in sliced tissues increased to the equal that in whole fruit within 24 hours of storage.
3. In both mature green fruit and ripe yellow fruit, the activities of ascorbate peroxidase were not influenced by wounding. The activities of monodehydroascorbate reductase in sliced yellow ripe fruit tissues stored at 20 °C increased during 12 hours after wounding, thereafter they decreased. On the other hand, the activities of monodehydroascorbate reductase in sliced mature green fruit tissues stored at 20 °C were not influenced by wounding. The activites of dehydroascorbate reductase in sliced tissue prepared from mature green fruit and ripe yellow fruit increased during 12 hours after cutting, and then decreased during the subsequent storage period.
4. The activities of catalase, glutathione reductase, and L-galactono-γ-lactone dehydrogenase in sliced tissues prepared from mature green fruit and ripe yellow fruit increased after cutting, and then decreased during subsequent storage period.
Our results suggest that wound stress by cutting activates the biosynthesis of ascorbic acid and reductases on ascorbic acid metabolism, so that the level of ascorbic acid in sweet pepper fruits remains high.