天然茶叶染料的提取及其稳定性的研究

用水煮法提取了天然茶叶染料,研究了茶叶色素的吸收光谱。对固液比、提取温度、浸提剂酸度、反应时间等提取条件进行了研究,并测定了色素在不同pH、温度等条件下的稳定性。结果表明,提取茶叶色素的最佳工艺条件为固液比1∶20,在沸煮(100℃)的条件下提取50分钟。该色素受pH影响较明显,对氧化剂、还原剂较敏感,但耐热稳定性较好。金属离子Ca2+、Cu2+、Zn2+、Mg2+、Na+、K+、Pb2+、Sn2+、Ni2+的存在对色素色泽基本无影响,Al3+、Fe2+、Fe3+的存在对色素有不良影响。茶叶色素易溶于水、乙醇、低浓度乙酸等极性溶液,不溶于苯、丙酮、氯仿、乙醚等非极性溶剂,属水溶性色素。

A Study on Extraction and Stability of Natural Tea Dyes

Natural tea dyes were extracted from tea by boiling water method and the absorption spectra of tea dyes were studied.The extraction conditions,including solid-liquid ratio,extraction temperature,acidity of extractant and reaction time were studied and the stability of dyes were determined in different pH and different temperature conditions.The results showed that the optimum extraction conditions of tea dyes were the solid-liquid ratio 1∶20 and extracting for 50 minutes in boiling water（100℃）.The dye was significantly affected by pH value,oxidant and reductant,but its thermal stability was good.Metal irons such as Ca2＋,Cu2＋,Zn2＋, Mg2＋,Na＋,K＋,Pb2＋,Sn2＋and Ni2＋ had no effect on the color,but Al3＋,Fe2＋and Fe3＋ had harmful effect.Tea dye is a water-soluble dye,easy to dissolve in water,ethanol,low concentration acetic acid and other polar solvents,and it is undissolved in benzene,acetone,chloroform,ether and other non-polar solvents.