茶叶中微量元素Cr、Cu、Fe、Mn、Ni、Zn的溶出率及化合态研究

Study on the chemical form and extraction rate of Cr,Cu,Fe,Mn,Ni and Zn in tea

用电感耦合等离子体—光发射光谱法 (ICP- OES)测定了市售茶叶中 Cr、Cu、Fe、Mn、Ni、Zn等微量元素的含量及各元素沸水溶出率 ,平均溶出率分别为 Cr 39.8%、Cu 42 .5 %、Fe 8.6 %、Mn 45 .5 %、Ni87.1%、Zn71.0 %。溶出率随浸泡次数增加而降低 ,总溶出量中 80 %的 Cr、Cu、Mn、Ni、Zn及 6 0 %的 Fe在第一次浸泡中被溶出。另外测定了 6种元素在茶水中的化学形态 ,其中有机态与无机态的比率分别为 Cr 0 .33、Cu0 .0 2 2、Fe0 .18、Mn0 .0 0 2、Ni0 .0 1、Zn0 .18。实验所得数据用于评估饮茶对 6种微量元素的实际摄入量 。

The content of Cr,Cu,Fe,Mn,Ni and Zn in the tea comm only available in China market were measured by inductivity coupled plasm a- optical emission spectrometry (ICP- OES) .The extraction rates of the six elements in tea leachate were measured.The solubilitied were39.8% for Cr,42 .5 % for Cu,8.6 % for Fe,45 .5 % for Mn,87.1% for Ni and 71.0 % for Zn.The process of m aking tea leachate affects the elem ents extraction rates.The content of the microelements in tea leave extracts decreasesgradually with the processing. About 80 % of Cr,Cu,Mn,Ni and Zn and 6 0 % of Fe were in the first infusion of tea.Moreover,the chemical forms of six elements were determ ined.The ratios of organic to inorganic forms were 0 .33 for Cr,0 .0 2 2 for Cu,0 .18for Fe,0 .0 0 2 for Mn,0 .0 1for Ni and 0 .18for Zn.It is concluded thatthe six elements from the tea infusion extracted from5 g tea are too little to meetthe recommend dietary allowance (RDA) . Therefore,tea is not a rich food source of Cr,Cu,Fe,Mn,Ni and Zn.