从茶叶中提取茶色素的研究

目的]研究低档绿茶中茶色素的提取并确定其最优提取工艺。方法]用有机溶剂提取法从茶叶中提取茶色素,以茶色素产率为指标,对提取时间、乙醇浓度和溶液pH值进行3因素3水平正交试验以优化工艺条件。通过溶解性试验和稳定性试验分析该茶色素对光、热的稳定性。结果]最优工艺条件为:将浸提的茶汁调pH值至6.5~7.0,用95%乙醇提取10 min,得茶色素产率为6.89%。茶色素为水溶性、醇溶性物质,但在1%醋酸溶液中的溶解度较纯水小,在0.5%氢氧化钠溶液中的溶解度比纯水大。该茶色素在酸性条件下可作棕黄色色素,中性条件下可作黄棕色色素,碱性条件下可作棕红色色素,并且其颜色稳定。茶色素水溶液对光比较稳定且有很强的耐热性。结论]茶色素是一种非常优良的天然色素。

Research on Extracting Tea Pigment from Tea Leaves

Objective] The purpose was to study the extraction of tea pigment from low-grade green tea and confirm its optimum extraction technology.Method] The tea pigment was extracted from tea leaves by organic solvent.With the yield of tea pigment as index,extraction time,ethanol concentration and pH value of solution were conducted for orthogonal experiment with 3 factors and 3 levels to optimize technical conditions.The light and heat stability of the tea pigment was analyzed through solubility and stability experiments.Result] The optimum technical conditions were moving pH value of tea extracts to 6.5～7.0 and extracting with 95% ethanol for 10 min.Under the conditions the obtained yield of tea pigment was 6.89%.Tea pigment was water-soluble and alcohol-soluble matter,but their solubility was smaller in 1% acetic acid solution and bigger in 0.5% sodium hydroxide solution than that in pure water.The tea pigment could be used as brown yellow pigment under acidic conditions,as yellow brown pigment under neutral conditions and as brown red pigment under alkali conditions and its color was stable.The water solution of tea pigment was more stable to light and had very strong heat resistance.Conclusion] Tea pigment was a kind of very good natural pigment.