Effect of Ca~(2+) on Sediment Formation in the Tea Infusion under Different Fermentation Degree

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 Ca2+, 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,P0.01) between the amount of tea sediment and Ca2+ concentration. The contents of polyphenols(r=0.95,P0.01), total sugars(r=0.99,P0.01), caffeine(r=0.82,P0.05) were also found to be highly correlated with the amount of tea sediment. Under the treatment of the same Ca2+ 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,P0.05) 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.