Phenolic content and antioxidant capacity of tropical highland blackberry (Rubus adenotrichus Schltdl.) during three edible maturity stages

Tropical highland blackberry (Rubus adenotrichus Schltdl.) is a good source of antioxidants and contains appreciable levels of phenolic compounds, mainly ellagitannins and anthocyanins. This study examined the influence of three ripening stages on phenolic contents. Major anthocyanin pigments increased from 0.20 (red fruit) to 1.34 mg g ^-1 fresh weight (FW) (fully ripe fruit), whereas ellagitannins and ellagic acid derivatives dropped from 3.8 to 2.2 mg ellagic acid equivalents g ^-1 (FW). Flavonols also dropped from 5.1 to 2.0 mg quercetin equivalents 100 g ^-1 (FW). Consequently, values for total phenolic compounds ranged from 5.8 to 5.2 mg gallic acid equivalents g ^-1 (FW), showing no specific trend. Antioxidant activity (H-ORAC) increased from 38.29 to 64.00 μmol of Trolox equivalents g ^-1 (FW) during ripening. When compared with other commercial cultivars, R. adenotrichus stands out for high H-ORAC value, although comparatively it possesses low anthocyanin content and average total phenolic content.