混浊苹果汁储藏过程中色泽稳定性的研究

通过HPLC等方法分析果汁中酚类和VC等物质在储藏中的变化，发现混浊苹果汁在储藏中发生的非酶褐变主要是由酚类的氧化聚合而引起，可通过低温储藏加以控制。聚原花色素、表儿茶素、绿原酸和VC的损失以及果汁的褐变随储藏时间的延长和温度的升高而加剧。果汁颜色变化先快后慢，L值降低，a值升高，b值变化较小。氮基酸也参与了褐变反应，但Maillard反应不显著。缩合单宁的平均聚合度随储藏时间的延长和温度的升高而变大。粒径分析表明储藏过程中有新的颗粒产生。

Studies on Color Stability during Storage of Cloudy Apple Juice

Non-enzymatic browning during the storage of cloudy apple juice was caused by the oxidation and polymerization of polyphenols and could be avoided by adding 0.006% VC(W/V)to juice or by storing at lower temperature.The degree of non-enzymatic browning and the loss of polymeric proanthocyanidin,epicatechin,chlorogenic acid and VC of juice increased with the increase of storage time and storage temperature.The color of juice changed much at the initial period of storage and then little.L value decreased,a value increased and b value changed little of the juice.The change of juice color is caused mainly by the oxidation and polymerization of polyphenols and degradation of VC.Free amino acids also contribute to the browning whereas Maillard reaction has little to do with it.The mean dgree of polymerization for polymeric proanthocyanidin also increase with increase of storage time and storage temperature.