Phenolic profiles and chemical- or cell-based antioxidant activities of four star fruit (Averrhoa carambola) cultivars

The objectives of this study were to investigate the phytochemical profiles and antioxidant activities of four cultivars of star fruit (Averrhoa carambola). The free, bound and total phenolic contents of the four cultivars were 162.5–286.8, 6.4–19.7, and 174.5–293.1 mg gallic acid equivalents per 100 g fresh weight (FW), respectively. The free, bound and total flavonoid contents were 100.7–234.0, 1.1–7.8, and 104.4–235.1 mg catechin equivalents per 100 g FW, respectively. The cellular antioxidant activity (CAA) values with or without a phosphate buffered saline wash protocol ranged from 25.80 to 63.29 and from 32.41 to 68.96 μmol quercetin equivalents per 100 g FW, respectively. The Taiguo cultivar had the highest phytochemical content and antioxidant activity among the four cultivars tested. High performance liquid chromatography analysis revealed the presence of gallic acid, syringic acid, p-coumaric acid, epicatechin, isoquercetin and procyanidin B2 in Averrhoa carambola. The type of cultivars influenced the phytochemical profile and extractability, antioxidant activity, and ultimately health-promoting potential of star fruit.