Compositions of anthocyanins in blackberry juice and their thermal degradation in relation to antioxidant activity

Abstract

This study investigated the compositions of anthocyanins in blackberry juice and the effect of heating (70, 80, and 90 °C) on individual anthocyanins, as well as its impact on antioxidant activity. The results showed that five anthocyanins were identified, including cyanidin (Cy)-3-O-glucoside (1), Cy-3-O-arabinoside (2), Cy-3-O-malonyl-glucoside (3), Cy-3-O-dioxalyl-glucoside (4), and the Cy derivative (5). The degradation rates of individual anthocyanins (1–4) followed the first-order reaction kinetics. Unexpectedly, the amount of the Cy derivative (5) was observed to slightly increase in temperature. At the same temperature, the half-lives (T 1/2) values of each anthocyanin (1–4) significantly differed (P < 0.05). Maximum of the T 1/2 values were observed with Cy-3-O-dioxalyl-glucoside (T 1/2 values ranged 9.48–3.54 h) and exhibited relatively resistant stability. Moreover, the T 1/2 values of Cy-3-O-glucoside were higher than Cy-3-O-arabinoside and Cy-3-O-malonyl-glucoside. The antioxidant activity of blackberry juice reduced with the decreasing of total anthocyanins. These results demonstrated that the time dependency of anthocyanins degradation and antioxidant capacity were strongly correlated in blackberry juice.