Abstract: The conditions of extraction of tea-polyphenols(TP)from tea dusts by precipitation method using metal ions Ca²⁺,Mg²⁺,Ba²⁺,Fe³⁺,Zn²⁺and Al³⁺ as precipitating agentshave been investigated.The influences of pH value,temperture,time,type and content ofbasic solutions used to regulate the pH value on the extraction rate of TP were examined.Itis shown that the extraction rate of TP could reach 10.5% and the content of the effective ingredients of TP could reach 99.5% by the proposed method.

Key words: tea-polyphenol, metalion, extraction, precipitation method