Ascorbate metabolism during maturation of sweet pepper (Capsicum annuum L.) fruit

Abstract

Changes in ascorbate metabolism during maturation of sweet pepper (Capsicum annuum L.) fruit 'Golden Bell' were investigated. The mature fruits were divided into four stages, based on changes in peel color from green to yellow; Green=100% green, Green/Yellow=10~20% yellow, Yellow/Green=50~60% yellow, Yellow=100% yellow. 1. Ascorbate content in sweet pepper fruit increased during maturation, whereas dehydroascorbate content remained at 1% throughout the maturation. 2. L-Galactono-γ-lactone dehydrogenase activity increased during maturation, the highest activity was occurring at Yellow stage. 3. Ascorbate peroxidase activity was highest at Green/Yellow or Yellow/Green stage and lowest at the Yellow stage. 4. Dehydroascorbate reductase activity was almost constant during maturation, whereas monodehydroascorbate reductase activity increased from Green to Yellow stage. From our results we attribute the increase of ascorbate contents during maturation to the increase in L-galactono-γ-lactone dehydrogenase and monodehydroascorbate reductase activities.