温度和质量浓度对茶多酚水溶液稳定性的影响

从色差、透光率、吸光度、pH值、电位和儿茶素含量变化探讨质量浓度和温度对茶多酚水溶液稳定性的影响。结果表明：不同质量浓度和温度贮存的茶多酚溶液稳定性差异都较大，其变化趋势主要表现为灭菌、贮存过程中，茶多酚溶液的亮度、透光率逐渐下降，溶液色泽和吸光度逐渐加深和增大，儿茶素含量和pH值呈现显著下降，且茶多酚质量浓度越高变化趋势越明显；25 ℃贮存时，色差、透光率、吸光度、pH值和儿茶素含量的变化程度均明显高于4 ℃贮存时；茶多酚溶液的电位绝对值随着质量浓度的增加逐渐减小，说明质量浓度低的茶多酚溶液较稳定。从变化趋势可判断出茶多酚质量浓度为400～800 mg/L，4 ℃贮存时，茶多酚稳定性相对较好，更适合保存和开发利用茶多酚。

Effect of Concentration and Temperature on the Stability of Tea Polyphenols in Aqueous Solution

The stability of tea polyphenols in aqueous solution as a function of concentration and temperature was
investigated with respect to the changes in color difference, transmittance, absorbance, pH values, zeta potential and
catechins contents. The results showed that the stability of tea polyphenols greatly varied with different concentrations
and temperatures. During the sterilization and storage, aqueous solution of tea polyphenols exhibited a gradual decrease
in lightness and transmittance, a darkened color appearance and consequently an increase in absorbance at 425 nm,
and a considerable reduction in catechins contents and pH. These changes were more marked at higher concentrations.
Significantly higher changes in color different, transmittance, absorbance, pH and catechins contents were observed when
stored at 25 ℃ than at 4 ℃. The zeta potential was negatively related to the concentration of tea polyphenols, suggesting that
these compounds were more stable at lower concentrations. Based on the above results, we conclude that tea polyphenols in
aqueous solution at concentrations between 400 and 800 mg/L are relatively stable when stored at 4 ℃.