[Study on the chemical form and extraction rate of Cr, Cu, Fe, Mn, Ni and Zn in tea].
The content of Cr, Cu, Fe, Mn, Ni and Zn in the tea commonly available in China market were measured by inductivity coupled plasma-optical emission spectrometry (ICP-OES). The extraction rates of the six elements in tea leachate were measured. The solubilitied were 39.8% 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 making tea leachate affects the elements extraction rates. The content of the microelements in tea leave extracts decreases gradually with the processing. About 80% of Cr, Cu, Mn, Ni and Zn and 60% of Fe were in the first infusion of tea. Moreover, the chemical forms of six elements were determined. The ratios of organic to inorganic forms were 0.33 for Cr, 0.022 for Cu, 0.18 for Fe, 0.002 for Mn, 0.01 for Ni and 0.18 for Zn. It is concluded that the six elements from the tea infusion extracted from 5 g tea are too little to meet the recommend dietary allowance (RDA). Therefore, tea is not a rich food source of Cr, Cu, Fe, Mn, Ni and Zn.
Gao
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Hygiene and Anti-Epidemic Centre of Chengdu, Chengdu 610021, China.
Tao
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D010936:Plant Extracts / Q000032:analysis; D013662:Tea / Q000737:chemistry*; D014131:Trace Elements / Q000032:analysis*; D015032:Zinc / Q000032:analysis*
D010936:Plant Extracts; D013662:Tea; D014131:Trace Elements; D015032:Zinc