Juice Yield and Anthocyanins Stability during the Processing of Blueberry

In this study, the effect of pectinase treatment on the yield of juice during the processing of blueberry fruits was studied. The pectinase-catalyzed processing conditions of blueberries were optimized. The effects of pH, temperature, light, metal ions, and additives on the stability of anthocyanins in blueberry juice were also explored. The results showed that the opt imal conditions for hydrolyzing blueberry pulp were found to be hydrolysis at 35 ℃ for 2 h with an enzyme dosage of 0.06%(m/m). Under these optimal conditions, the yield of blueberry juice was 82.1%, showing a 24.6% increase over controls. The anthocyanins in blueberry juice were stable at pH 3 or less, but sensitive to light and high temperatures. Vitamin C could increase the stability of these anthocyanins, but sodium benzoate and sucrose had no obvious impact on their stability. K+, Na+, Ca2+, Cu2+ and Fe2+ had no obvious impact on their stability. Fe3+ and 0.1 mol/L Mg2+ were harmful to the stability of the anthocyanins, but Mg2+ at concentrations less than 0.05 mol/L could increase the stability of the anthocyanins.