茶汤组分与金属离子的络合性能

用直接观察法、酒石酸亚铁法和铬黑 T 祛对绿茶茶汤组分与23种金属离子的络合性能进行了研究,结果表明,有22种金属离子可与茶汤组分发生络合或还原络合反应,其中有10种金属离子参与了茶多酚的络合。钙离子可与茶汤组分生成低溶解度的络合物,其溶解度及稳定性可随反应溶液 pH 升高而下降。钙络合沉淀中的主要茶汤组分是茶多酚,其中以酯型儿茶素含量最高。

Complex of Tea Infusion Components With Metal lons

The complex properties of the green tea infusion components with 23kinds of metal ions were investigated by the methods of direct observation,or using ferrous tartrate and Eriochrome Black T as indicators.It was co-nfirmed that 22 kinds of metal ions reacted with the tea infusion compone-nts,of them,10 reacted with the polyphenols.Ca~(2+)-complex of lower solu-bility could be easily obtained.The water solubility and the stability ofCa~(2+)-complex decreased with the increasing of pH value.By using pure teacomponents to react with Ca~(2+)ions,it was confirmed that under the sameconditions as tea infusion,amino acids,caffeine,and carbohydrates didn'treact with Ca~(2+)to form the precipitation of complex.The main tea compo-nents in the Ca~(2+)-complex precipitation Were polyphenols,and the highestones were(-)-EGCG and(-)-ECG.