Wróbel K, Wróbel K, Urbina E M
Instituto de Investigaciones Científicas, Universidad de Guanajuato, Mexico.
Biol Trace Elem Res. 2000 Winter;78(1-3):271-80. doi: 10.1385/BTER:78:1-3:271.
Total aluminum, chromium, copper, iron, manganese, and nickel were determined in black tea, green tea, Hibiscus sabdariffa, and Ilex paraguariensis (mate) by electrothermal atomic absorption spectrometry after nitric/perchloric acid digestion. In each case, one ground sample of commercially available leafy material was prepared and three 0.5-g subsamples were run in parallel. The infusions were also analyzed and the percentage of each element leached into the liquor was evaluated. The obtained results indicated that hibiscus and mate contained lower levels of aluminum (272+/-19 microg/g and 369+/-22 microg/g, respectively) as referred to black tea (759+/-31 microg/g) or green tea (919micro29 microg/g) and suggested that mate drinking could be a good dietary source of essential micronutrient manganese (total content 2223+/-110 microg/g, 48.1% leached to the infusion). It was also found that the infusion of hibiscus could supply greater amounts of iron (111+/-5 microg/g total, 40.5% leached) and copper (5.9+/-0.3 microg/g total, 93.4% leached) as compared to other infusions. Moreover, it was found that the percentage of element leached to the infusion was strongly related to the tannins content in the beverage (correlation coefficients > 0.82 with the exception for nickel); for lower tannins level, better leaching was observed.
采用电热原子吸收光谱法，在经硝酸/高氯酸消解后，测定了红茶、绿茶、玫瑰茄和巴拉圭冬青（马黛茶）中的总铝、铬、铜、铁、锰和镍含量。每种情况下，均制备了一份市售叶状材料的磨碎样品，并平行测定了三个0.5克的子样品。还对浸出液进行了分析，并评估了每种元素浸出到茶汤中的百分比。所得结果表明，与红茶（759±31微克/克）或绿茶（919±29微克/克）相比，玫瑰茄和马黛茶中的铝含量较低（分别为272±19微克/克和369±22微克/克），这表明饮用马黛茶可能是必需微量营养素锰的良好膳食来源（总含量为2223±110微克/克，48.1%浸出到浸出液中）。还发现，与其他浸出液相比，玫瑰茄浸出液能提供更多的铁（总含量为111±5微克/克，40.5%浸出）和铜（总含量为5.9±0.3微克/克，93.4%浸出）。此外，还发现元素浸出到浸出液中的百分比与饮料中的单宁含量密切相关（除镍外，相关系数>0.82）；单宁含量较低时，浸出效果更好。
