Evaluation of the antioxidant properties of fruits

Twenty-eight different fruits were analysed for antioxidant activities using two different methods, one that determines the inhibition of ascorbate/iron-induced peroxidation of phosphatidylcholine, by means of thiobarbituric acid-reactive substances (TBARS) measurement, and another that evaluates the scavenging of the radical cation of 2,2′-azinobis (3-ethyl-benzothiazoline-6-sulphonate) (ABTS) relative to Trolox C, a water-soluble vitamin E analogue. The values of the antioxidant capacities of the analysed fruits were in a wide range from 50 g to more than 5 mg for the IW50 (dry weight causing 50% inhibition of lipidic peroxidation) and from it 406 μmol/g for the TEAC (μmol Trolox equivalents g−1). There was no significant correlation between antioxidant activity (IW50 and TEAC) and the contents of flavanol of the samples. The antioxidant activities of the analysed fruits cannot only be attributed to their flavanol contents, but to the result of the action of different antioxidant compounds present in the fruits and to possible synergic and antagonist effects still unknown.