Antioxidant, free radical scavenging activities and total polyphenolic content of aqueous extracts from seven blueberry cultivars grown in New Zealand

Abstract

ABSTRACT Antioxidant activity in blueberries or other fruits is an appealing characteristic to consumers and food industries. The antioxidant properties of aqueous extracts prepared from the berries of five rabbiteye (Vaccinium ashei) and two highbush (V. corymbosum) cultivars of blueberry grown in New Zealand, were studied using ferric reducing antioxidant power (FRAP) and scavenging DPPH (2, 2-diphenyl-1-picrylhydrazyl) free radical assays. Their ferrous ion chelating activities and total polyphenol contents (TPC) were also determined. Significant differences were found in antioxidant/antiradical activities and TPC among various cultivars of blueberries. The results showed that the highest TPC among the highbush cultivars were detected in the extracts from the berries of Jersey while the lowest TPC were detected in the extracts from the berries of Dixi. Similarly, the antioxidant/antiradical activity was significantly higher in Jersey than in Dixi cultivar which indicates that the antioxidant activity is related to the total phenolic contents. Among the rabbiteye cultivars, Centurion had the highest TPC followed by cultivars Maru, Rahi, Tifblue, and Ono. Regarding the antioxidant activity among the rabbiteye cultivars, it was in accordance with the results of TPC for all cultivars studied in that Centurion had the highest FRAP value and Ono cultivar had the lowest. A similar trend of activity was observed regarding the DPPH radical scavenging capacities. This may confirm that the phenolic compounds found in the blueberry extracts are the main contributors of the antioxidant/antiradical activities. In general, rabbiteye cultivars had significantly higher TPC (P < 0.01), higher antioxidant (P < 0.05) and free-radical scavenging activity (P < 0.05) than highbush cultivars.