State Higher Vocational School in Tarnow, Mickiewicza 8 St., 33-100, Tarnow, Poland.
Department of Food Chemistry and Nutrition, Medical College, Jagiellonian University, Medyczna 9 St., 30-688, Cracow, Poland.
Biol Trace Elem Res. 2018 Jun;183(2):389-395. doi: 10.1007/s12011-017-1140-x. Epub 2017 Sep 2.
Concentrations of selected metals (Cu, Mn, Zn, Cd) in tea leaves were investigated. Samples included black, green, and other (red, white, yellow, and oolong) teas. They were purchased on a local market but they covered different countries of origin. Beverages like yerba mate, rooibos, and fruit teas were also included in the discussion. Metal determinations were performed using atomic absorption spectrometry. In black teas, Mn/Cd ratio was found to be significantly higher (48,091 ± 35,436) vs. green (21,319 ± 16,396) or other teas (15,692 ± 8393), while Cd concentration was lower (31.4 ± 18.3 μg/kg) vs. other teas 67.0 (67.0 ± 24.4). Moreover, Zn/Cu and Cu/Cd ratios were, respectively, lower (1.1 ± 0.2 vs. 2.2 ± 0.5) and higher (1086 ± 978 vs. 261 ± 128) when comparing black teas with other teas. Intake of each metal from drinking tea was estimated based on the extraction levels reported by other authors. Contributions to recommended daily intake for Cu, Mn, and Zn were estimated based on the recommendations of international authorities. Except for manganese, tea is not a major dietary source of the studied elements. From the total number of 27 samples, three have shown exceeded cadmium level, according to local regulations.
研究了茶叶中选定金属（Cu、Mn、Zn、Cd）的浓度。样本包括黑茶、绿茶和其他茶（红茶、白茶、黄茶和乌龙茶）。这些茶叶是在当地市场购买的，但来自不同的原产国。讨论还包括马黛茶、路易波士茶和水果茶等饮料。金属测定采用原子吸收光谱法进行。在黑茶中，Mn/Cd 比值明显高于绿茶（21,319±16,396）或其他茶（15,692±8393），而 Cd 浓度较低（31.4±18.3μg/kg），低于其他茶（67.0±24.4μg/kg）。此外，与其他茶相比，Zn/Cu 和 Cu/Cd 比值分别较低（1.1±0.2 对 2.2±0.5）和较高（1086±978 对 261±128）。基于其他作者报道的提取水平，估算了从饮茶中摄入每种金属的量。基于国际权威机构的建议，估算了 Cu、Mn 和 Zn 的推荐日摄入量的贡献。除了锰，茶不是这些研究元素的主要膳食来源。在总共 27 个样本中，根据当地法规，有三个样本显示 Cd 含量超标。
