热协同超高压加工的鲜榨桃汁在贮藏过程中的稳定性变化

Color Stability of Fresh Peach Juice Prepared by Heating at High Pressure during Storage

通过HPLC等方法分析用热协同超高压加工的鲜榨桃汁中酚类和Vc等物质在贮藏中的变化,发现果汁在贮藏中发生的非酶褐变主要是由酚类的氧化聚合而引起,可通过低温贮藏加以控制。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贮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。氨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贮藏时间的延长和温度的升高而变大。粒径分析表明贮藏过程中有新的颗粒产生。

Contents of several compounds （polyphenols, Vc, etc.） in fresh peach juice made by heating at high pressure during 120-day storage were analyzed by HPLC, It was found that the oxidation and polymerization of polyphenols mainly accounted for the non-enzymatic browning of peach juice during the storage, which could be avoided by low-temperature storage of the juice. The non-enzymatic browning of the juice was enhanced and the loss of polymeric proanthocyanidin, epicatechin, chlorogenic acid and Vc in the juice increased by increasing the storage time and temperature. During the storage of the juice, L^＊ value decreased, a^＊ value increased and b value changed little. Free amino acids also contributed to the browning of juice. Besides, the mean degree of polymerization for polymeric proanthocyanidin increased as improving the storage time and temperature. The size distribution analysis showed that new particles formed during the storage of juice.