Changes in Antioxidant Activity, Total Phenolics and Ascorbic Acid Content during Fruit Ripening in Korean Cultivars of Rubus coreanus

Rubus coreanus is a perennial shrub distributed in the southern part of Korea. Its unripe fruit has been used in traditional herbal medicine for the treatment of diabetes mellitus and sexual disinclination. The fruit of R. coreanus was also found to have antioxidant activity. While there are some data on the constituents and biological activities of R. coreanus fruits, there are no studies on the chemical composition and antioxidant activity of R. coreanus fruits during ripening. Therefore, changes in the overall antioxidant properties of R. coreanus fruit during ripening are studied. Correlations between total phenolic content and ascorbic acid were also examined. R. coreanus fruits of three clones (S-13, S-14, and S-16), grown in the Korea Forest Institute (Suwon) were utilized. The antioxidant activities of the fruit 5 days after fruit set of three clones (S13, S14, and S16) were 59.9, 75.8, and 81.2% at the concentration of 125µg/ml. Total phenolic content in fruit of 5 days after fruit set of three clones (S13, S14, and S16) were 260.5, 254.3, and 235.5µg/g, respectively. When fruits were 5 days old, vitamin C content were 572.4, 541.2, 574.4µg/g for S13, S14 and S16, respectively. Total phenolic content of R. coreanus fruits (S-13, S14, and S16) was correlated with antioxidant activity (R ²=0.87, 0.97, 0.94).