Sugars, organic acids, phenolic compositions and antioxidant activity of Grapefruit (Citrus paradisi) cultivars grown in Turkey

This research was undertaken to determine the sugars, organic acids, phenolic compositions and antioxidant capacities of grapefruits (cvs. Rio red, Star ruby, Ruby red and Handerson) grown in Turkey. High-performance liquid chromatographic methods were used to identify and quantify three sugars (sucrose, glucose and fructose) and five organic acids (oxalic, citric, ascorbic, malic and succinic acids). The major organic acid was found as citric acid. With regard to sugars, sucrose was present in the largest amounts for grapefruit juices. The sum of sugars ranged from 75.81 to 85.43 g L−1 and the sum of organic acids ranged from 22.50 to 26.78 g L−1. A total of 15 phenolic compounds were identified and quantified in grapefruit juices, including hydroxybenzoic acids (4), hydroxycinnamic acids (5), and flavanones (6) compounds. Total phenolic content ranged from 441.09 (Ruby red) to 725.71 mg L−1 (Star ruby) and antioxidant activity (AE) ranged from 34.51(Ruby red) to 128.37 × 10−3 (Star ruby).