Antioxidant capacities, total phenolic and ascorbic acid content of fruit available in New Zealand

Abstract

Methods: Antioxidant capacities, total phenolic and ascorbic acid contents of 40 fruit available in New Zealand were quantified using ABTS and ORAC, Folin­-Ciocalteu and titration assays respectively. The fruits contained a wide range of these activities. Results: These ranged from 122.3 to 13,631.6 µmol Trolox equivalents (TE)/100 g FW for ORAC; 19.5 to 6045.9µmol TE/100 g FW for ABTS; 27.4 to 2731.9 mg gallic acid equivalent (GAE)/100 g FW for total phenolic concentrations and 6.2 to 201.3 mg ascorbic acid/100 g FW. Berries showed the highest antioxidant capacities along with high total phenolics and ascorbic acid contents. Both antioxidant capacities, ORAC and ABTS were significantly correlated to the total phenolic concentrations (p < 0.001) while no relationship between ascorbic acid and ABTS and only a weak correlation between ascorbic acid and ORAC (p < 0.05) were found. The calculated contribution of ascorbic acid to ORAC values was less than 20% for all fruits except green kiwifruit (40.5%), golden kiwifruit (37.5%), tamarillo (29.7%), persimmon (24%) and pineapple (23.4%). Conclusion: Together these correlations suggest that phenolic compounds are primarily responsible for the free radical scavenging ability of fruit, while ascorbic acid plays a lesser role.