电感耦合等离子体发射光谱法测定黑茶元素溶出特性

Determination of Dissolving-out Characteristics of Black Tea Elements by Inductively Coupled Plasma Atomic Emission Spectrometry

黑茶是采用茶叶为原料经杀青、初揉、渥堆及干燥等工序加工而成的后发酵茶,富含K、Ca、Mg、Zn等多种有益元素,是航天飞行过程中乘组补充多种元素的优良食材。为考察黑茶浸泡过程中元素溶出特性,分别对黑茶元素含量及泡茶水中相应元素进行测定。采用密闭高压微波消解法进行样品消化,避免了消化过程中元素的损失。采用电感耦合等离子体发射光谱法同时测定了黑茶中K、Mg、Al、Mn、Zn、Fe及Ca元素的含量。采用去离子水模拟泡茶程序,梯度浸泡5次,分别取茶水,基质匹配后上机测定。实验结果表明,方法回收率在96.4%-106.7%,首次浸泡茶水中K、Mg、Al、Mn、Zn、Fe及Ca溶出量占相应元素含量的百分比依次为45.35%,6.23%,2.16%,1.68%,7.8%,2.0%及0.4%,Ca溶出率最低,浸泡茶水中K、Mg、Al、Mn元素溶出率与浸泡次数呈指数关系,溶出方程分别为y=105.75e^-0.874 3x,y=9.949 3e^-0.969 5x,y=6.335 8e^-1.406 5x及y=4.247 7e^-1.339 4x,相关系数R2分别为0.986,0.928 3,0.950 7及0.926。

Black tea is produced by successive procedure such as cranking up of raw material,first rubbing,fermenting,and drying processes,which is rich in a variety of minerals,such as K,Ca,Mg,and Zn. Black tea is benefit for astronauts. In order to investigate the dissolving-out characteristics of black tea,elements of black tea powder and black tea soup were analyzed. The closed high-pressure microwave digestion method was used for sample digestion to avoid the loss of elements during the digestion procedure. The concentration of seven minerals including K,Mg,Al,Mn,Zn,Fe,and Ca were measured by inductively coupled plasma atomic emission spectrometry（ ICP-OES）. The tea soup was made using deionized water for 5 times. The results showed that the method recoveries ranged from 96. 4% to 106. 7%and the dissolving-out yields of K,Mg,Al,Mn,Zn,Fe,and Ca were 45. 35%,6. 23%,2. 16%,1. 68%,7. 8%,2. 0%,and 0. 4% respectively,in the first tea soup. There was an exponential relationship between the dissolving-out yields of K,Mg,Al,and Mn and soaking times. The exponential relationship equations between the dissolving-out rate for K,Mg,Al,and Mn in black tea and soak times were y = 105. 75e^- 0. 874 3x,y = 9. 949 3e^- 0. 969 5x,y = 6. 335 8e^- 1. 406 5x,and y = 4. 247 7e^- 1. 339 4x,respectively. The correlation coefficients were 0. 986,0. 928 3,0. 950 7,and 0. 926,respectively.