Ascorbic Acid Content in Relation to Ascorbic Acid Oxidase Activity and Polyamine Content in Tomato and Bell Pepper Fruits During Development, Maturation and Senescence

Tomato (Lycopersicum esculentum Mill, cv. XPH-1251) and bell pepper (Capsicum annuum, cv. New ace) plants were grown in a greenhouse in controlled hydroponic conditions, and fruits were harvested at different intervals from 18 to 94 days from fruit set. Total ascorbic acid was higher in bell pepper than in tomato fruit. In pepper fruit, the level increased rapidly during its development, reaching a maximum of 136.1 mg/100 g at 51 days from fruit set and then decreased suddenly, reaching a minimum of 65.5 mg/100 g at 64 days. Ascorbic acid in tomato fruit increased slowly reaching a maximum of 94.9 mg/100 g at 74 days and then declined slowly. The decrease in ascorbic acid coincided with the initiation of ripening, as indicated by color change, and with an increase in the activity of ascorbate oxidase. There was more putrescine in bell pepper than in tomato fruit. No major changes were observed in spermine and spermidine in bell pepper and in spermidine in tomato fruits. However, putrescine in bell pepper fruit and spermine in tomato fruit increased very early until about 30-38 days and then decreased. We conclude that ascorbic acid decreases in tomato and bell pepper fruits after 74 and 51 days, respectively, and this decrease coincided with an increase in ascorbate oxidose, as well as a decrease in putrescine in pepper and spermine in tomato fruit.