Study on color formation of green tea liquor caused by complexation of pigments with the other components.

铜、铁、铝离子对单糖芦丁水溶液有增色作用。儿茶素对溶液有减色作用，且没食子酸酯类儿茶素的作用大于非没食子酸儿茶素。儿茶素与单糖芦丁形成1：1的络合物。没食子酸酯类儿茶素的结合常数大于非没食子酸酯类儿茶素。这些结果表明，没食子酸型儿茶素与单糖芦丁之间的络合作用是导致单糖芦丁溶液变色的原因。加入表没食子儿茶素没食子酸酯后，金属-单糖芦丁混合溶液的颜色变浅，但比只加表没食子儿茶素没食子酸酯的单糖芦丁溶液颜色深。

Copper, iron, and aluminium ions caused hyperchromic effect to monoglucosyl rutin aqueous solution. Catechins caused hypochromic effect to the solution, and the effect of gallate-type catechins was greater than that of non-gallate-type catechins. Catechins formed 1:1 complexes with the monoglucosyl rutin. Binding constants were larger in gallate-type catechins than in non-gallate-type catechins. These results suggest that the complexation between gallate-type catechins and monoglucosyl rutin are responsible for the color change of the monoglucosyl rutin solution. The color of the metal-monoglucosyl rutin mixture solution became paler by adding epigallocatechin gallate to the solution, nonetheless, the color was deeper than that of the monoglucosyl rutin solution added epigallocatechin gallate only.