为研究绿茶浓缩汁中不可逆沉淀的化学组成及其形成过程，本文分析了茶浓缩汁中不可逆沉淀与可逆沉淀的主要化学组成，及低温条件下不同贮藏阶段（0~20 d，20~180 d，180~250 d）不可逆沉淀与可逆沉淀的形成情况。研究结果表明，不可逆沉淀含有大量金属元素和草酸根离子，而可逆沉淀主要由茶多酚、碳水化合物、咖啡碱、蛋白质及黄酮化合物组成；浓缩汁沉淀以可逆沉淀为主，不可逆沉淀较少；随着贮藏时间延长，沉淀量逐渐增加，但大部分可逆与不可逆沉淀都在0~20 d形成；元素Mg、Mn、Ga、Ni和Zn主要是在0~20 d参与不可逆沉淀形成，Fe和Cu主要在20~180 d，而Al和Ca主要是在180~250 d。另外，本文还验证了鞣花酸能与蛋白质结合产生不可逆沉淀。本文结果说明绿茶浓缩汁不可逆沉淀主要是不溶性草酸盐。

In order to study the chemical constitutes and forming process of irreversible sediment in green tea concentrate, the main chemical components and the forming of irreversible and reversible sediment at different storage periods (0~20 d, 20~180 d, 180~250 d) under low-temperature conditions were studied and compared. The results showed that irreversible sediment contained large amounts of mineral elements and oxalic ion, while reversible sediment was comprised of polyphenols, carbohydrates, caffeine, protein and flavones. Most of sediment in green tea concentrate was reversible tea sediment. During storage of green tea concentrate, sediment contents increased, and most of the reversible and irreversible tea sediment were formed during 0~20 d. Elements as Mg, Mn, Ga, Ni and Zn mainly were participated in the formation of irreversible sediment during 0~20 d, Fe and Cu were during 20~250 d, and Al and Ca were during 180~250 d. In addition, the combination of ellagic acid and protein were also confirmed to form irreversible sediment. This research revealed that irreversible sediment was mainly composed by insoluble oxalates.

国家自然科学基金项目（31070615）；浙江省茶产业技术创新战略联盟专项资金项目（2010LM201-16）及浙江省茶叶加工工程重点实验室开放课题（2010K1004）