双水相纯化湖南黑茶茶多酚工艺优化

Optimization of Purification Technology of Tea Polyphenols from Hunan Dark Tea by Aqueous Two-phase System

选用PEG-(NH4)2SO4双水相体系对湖南黑茶茶多酚进行分离纯化.通过单因素实验考察PEG的平均分子量与质量分数、硫酸铵质量分数、提取液体积、体系pH值和温度等多种因素对茶多酚纯化的分配系数以及萃取率的影响,并选择正交实验对茶多酚纯化工艺条件进行进一步优化.实验表明,双水相纯化湖南黑茶茶多酚的最佳工艺条件为:10.0 g双水相体系中,选用平均分子量为600、质量分数为30%的PEG,质量分数为21%的(NH4)2SO4,体系的提取液体积为2.7 mL,pH=5.5,温度为25℃.在此最优工艺条件下,可得双水相纯化湖南黑茶茶多酚的分配系数为34.50,萃取率可达97.57%.

The tea polyphenols from Hunan Dark Tea were separated and purified by PEG-(NH4)2SO4 aqueous two-phase system. The effects of the average molecular weight and mass fraction of PEG, the mass fraction of ammonium sulfate, the volume of extraction liquid, the pH and temperature of the system on the partition coefficient and extraction rate of tea polyphenols were investigated by single factor experiment. Orthogonal experiments were selected to further optimize the purification conditions of the tea polyphenols. The experiments showed that the optimum technological conditions for the purification of the tea polyphenols from Hunan Dark Tea by aqueous two-phase method were as follows: in 10.0 g aqueous two-phase system, PEG with an average molecular weight of 600 and a mass fraction of 30% was selected, and the mass fraction was 21%(NH4)2SO4, the volume of extraction liquid was 2.7 mL, the pH was 5.5, and the temperature was 25 ℃. Under the optimal purification conditions, the partition coefficient of tea polyphenols purified by aqueous two-phase method was 34.50, and the extraction rate was 97.57%.