Study on Anti Enzymatic Browning in Blueberry Cloudy Juice Processing

Blueberry is enriched with polyphenol oxidase(PPO) which is very active to react with polyphenolics,resulting in deteriorative change of juice.Preventing enzymatic browning before pressing blueberries can improve the quality of juice efficiently.Two kinds of methods,VC addition and steam blanching,were used to prevent browning in this work,and their effects on juice quality were studied.Adding 0.05% VC could inhibit PPO and protect the color of juice,but almost had no effect on the recovery of anthocyanins pigments and total polyphenolics.Blanching blueberry for 2 min was able to inactivate PPO completely,avoid browning,increase anthocyanins and total polyphenolics contents significantly.Furthermore juice from blanched fruits exhibited better blue color and the color was more stable.