Determination of oxalate content in tea samples by high performance liquid chromatography

This study was conducted to determine oxalate content in tea samples and study the effect of steeping duration on the oxalate content. One-hundred and twenty samples of both leaf and bag forms of tea-white, green, oolong, and black teas from 40 brands-were purchased from markets in Thailand from February to June 2011. The oxalate content was measured by the high performance liquid chromatography (HPLC) method. The results showed that in leaf form, the highest oxalate content was found in black tea (2.32 ± 1.10 mg/g tea), then in oolong tea (1.62 ± 0.79 mg/g tea), green tea (1.41 ± 0.56 mg/g tea) and lowest in white tea (1.29 ± 0.33 mg/g tea). In bag form, the oxalate content in black tea (2.37 ± 0.80 mg/g tea) was higher than that of oolong tea (1.88 ± 1.04 mg/g tea). The amount of oxalate in green tea (1.24 ± 0.48 mg/g tea) was comparable with that of white tea (1.25 ± 0.45 mg/g tea). The forms (leaf or bag) of tea did not have significant influence on the amount of oxalate. Steeping the tea for a longer duration provided more oxalate content. People with high risk of kidney stones should avoid drinking high amounts of black tea. Steeping tea for a short duration is also recommended for limiting oxalate intake.本研究旨在测定茶叶样品中的草酸含量，并探究浸泡时长对草酸含量的影响。2011年2月至6月，我们于泰国市场采购了40个品牌的白茶、绿茶、乌龙茶、红茶的散叶与袋泡茶两类形态样品，共计120份。采用高效液相色谱法（High Performance Liquid Chromatography，HPLC）对样品草酸含量进行测定。结果显示：散叶茶形态下，草酸含量由高到低依次为红茶（2.32±1.10 mg/g茶叶）、乌龙茶（1.62±0.79 mg/g茶叶）、绿茶（1.41±0.56 mg/g茶叶），白茶草酸含量最低。袋泡茶形态下，红茶草酸含量（2.37±0.80 mg/g茶叶）高于乌龙茶（1.88±1.04 mg/g茶叶）；绿茶草酸含量（1.24±0.48 mg/g茶叶）与白茶（1.25±0.45 mg/g茶叶）相当。茶叶形态（散叶或袋泡）对草酸含量无显著影响。延长茶叶浸泡时长可提升草酸析出量。肾结石高风险人群应避免大量饮用红茶，同时建议缩短浸泡时长以限制草酸摄入。

搜集汇总

背景与挑战

背景概述

该数据集记录了采用高效液相色谱法（HPLC）测定泰国市场40个品牌120个茶叶样品（包括叶片和袋装形式）中草酸盐含量的研究结果。研究表明红茶草酸盐含量最高，且浸泡时间越长草酸盐溶出越多，为肾结石高风险人群提供了减少草酸盐摄入的饮食建议，如避免大量饮用红茶并缩短浸泡时间。