钙离子对不同发酵程度茶汤沉淀形成的影响

摘要

In order to investigate the effect of Ca2+ on sediment formation in tea infusion, which was prepared by dissolving different instant tea powders with the water containing different concentrations of Ca 2+, the amount and chemical components contents of tea sediment were analyzed. The results showed that, the amount of tea sediment increased with the increasing concentration of Ca2+(5 to 40 mg·L-1) in green tea infusion and there was significant positive correlation (r=0.98,P<0.01) between the amount of tea sediment and Ca2+concentration. The contents of polyphenols (r=0.95,P<0.01), total sugars (r=0.99,P<0.01), caffeine (r=0.82,P<0.05) were also found to be highly correlated with the amount of tea sediment. Under the treatment of the same Ca 2+ concentration, the amount of tea sediment of green tea, Tiguanyin tea, Wuyi tea, black tea and Pu′er tea were significant different. With the deepening of fermentation degree of different teas, the amount of sediment in different tea infusion increased. However, the effect of Ca2+on tea sediment formation decreased. After analysis, there was a significant correlation (r=0.78,P<0.05) between the polyphenols contents in tea infusions and the increasing rates of tea sediments. It indicated that Ca2+could improve tea sediment formation by affecting the behavior of polyphenols.%用含钙离子水冲泡速溶茶粉，研究了不同浓度钙离子对绿茶茶汤沉淀形成的影响，以及钙离子对不同发酵程度茶类茶汤沉淀形成的影响。结果表明，随着钙离子质量浓度（5~40 mg·L-1）的增加，绿茶茶汤的沉淀量呈逐渐增加趋势，钙离子质量浓度与绿茶沉淀量之间具有显著正相关（r=0.98，P＜0.01），而沉淀中的茶多酚（r=0.95，P＜0.01）、总糖（r=0.99，P＜0.01）和咖啡碱（r=0.82，P＜0.05）含量也与沉淀量呈显著正相关。相同钙离子浓度下，绿茶、铁观音、武夷岩茶、红茶、普洱茶茶汤沉淀形成量差异较大。随着茶叶发酵程度的加重，茶汤沉淀量呈增加的趋势，而钙离子对茶汤沉淀形成的促进作用逐步降低。通过分析发现，钙离子促进沉淀形成的增长率与茶汤中茶多酚所占的比率有显著相关性（r=0.78，P＜0.05），说明钙离子可能是主要通过影响茶多酚的络合作用来促进茶汤沉淀的形成。