Gallic acid as a copigment enhance anthocyanin stabilities and color characteristics in blueberry juice.

The aim of this study was to evaluate the influence of adding copigment gallic acid (GA) on the stability of anthocyanin and color in blueberry juice, and assays were carried out with different anthocyanin:GA molar ratios (1:0, 1:1, 1:3, 1:5) in accelerated experiments (40 °C for 10 days). Results showed that the addition of GA made blueberry juice to appear more crimson color tonality, color saturation and anthocyanins stability. The most obvious hyperchromic effect appeared in juice with 1:5 of anthocyanin:GA molar ratios, and in this ratio, total anthocyanin content (137.67 mg/L) and main anthocyanin peonidin-3-glucoside content (51.68 mg/L) of the blueberry juice were higher than juice without copigment (total anthocyanin of 116.96 mg/L and peonidin-3-glucoside of 34.2 mg/L). Furthermore, anthocyanins in blueberry juice copigmented with molar ratios 1:5 of anthocyanin:GA were more stable at 4 °C than that at 25 °C and 40 °C. Thus, the addition of gallic acid at appropriate levels might be a promising juice process technology to obtain juices with high color quality and anthocyanin stability.