Determination of tea components with antioxidant activity
Determination of tea components with antioxidant activity
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DOI：
10.1021/jf0300801
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发表时间：
2003-07-16
影响因子：
6.1
通讯作者：
López, MC
中科院分区：
文献类型：
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作者：
Cabrera, C;Giménez, R;López, MC
具有抗氧化活性的基本元素的水平，以及儿茶素，没食子酸和咖啡因的水平，在西班牙商业化的不同茶的45个样品中进行了评估。铬，锰，硒，锌的测定与硝酸和V2 O 5矿化的样品中，使用ETAAS作为分析技术。通过分析经认证的参考物质来检查该方法的可靠性。观察到茶叶的微量元素组成变化很大。铬的含量范围为50.6至371.4纳克/克，锰的含量范围为76.1至987.6纳克/克，硒的含量范围为48.5至114.6纳克/克，锌的含量范围为56.3至78.6纳克/克。采用高效液相色谱法，采用光电二极管阵列检测器，同时测定表没食子儿茶素没食子酸酯（EGCG）、表没食子儿茶素（EGC）、表儿茶素没食子酸酯（ECG）和表儿茶素（EC）、没食子酸（GA）和咖啡因。在所有分析的样品中，EGCG范围为1.4至103.5 mg/g，EGC范围为3.9至45.3 mg/g，ECG范围为0.2至45.6 mg/g，EC范围为0.6至21.2 mg/g。这些结果表明，绿色茶的儿茶素含量高于乌龙茶和发酵茶（红茶和红茶）;茶叶制造过程中的发酵过程显着降低了儿茶素的水平。没食子酸含量范围为0.039至6.7 mg/g;发酵过程还显著提高了红茶中的没食子酸水平（平均水平为3.9 +/- 1.5 mg/g）。分析样品中咖啡因的含量范围为7.5至86.6 mg/g，在绿色茶和乌龙茶中检测到较低的值。本研究将有助于各种茶中微量元素和抗氧化成分的评价，也将对喜欢喝这种饮料的人感兴趣。
Levels of essential elements with antioxidant activity, as well as catechins, gallic acid, and caffeine levels, in a total of 45 samples of different teas commercialized in Spain have been evaluated. Chromium, manganese, selenium, and zinc were determined in the samples mineralized with HNO3 and V2O5, using ETAAS as the analytical technique. The reliability of the procedure was checked by analysis of a certified reference material. Large variations in the trace element composition of teas were observed. The levels ranged from 50.6 to 371.4 ng/g for Cr, from 76.1 to 987.6 mug/g for Mn, from 48.5 to 114.6 ng/g for Se, and from 56.3 to 78.6 ng/g for Zn. The four major catechins epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and epicatechin (EC)], gallic acid (GA), and caffeine were simultaneously determined by a simple and fast HPLC method using a photodiode array detector. In all analyzed samples, EGCG ranged from 1.4 to 103.5 mg/g, EGC from 3.9 to 45.3 mg/g, ECG from 0.2 to 45.6 mg/g, and EC ranged from 0.6 to 21.2 mg/g. These results indicated that green tea has a higher content of catechins than both oolong and fermented teas (red and black teas); the fermentation process during tea manufacturing reduces the levels of catechins significantly. Gallic acid content ranged from 0.039 to 6.7 mg/g; the fermentation process also elevated remarkably gallic acid levels in black teas (mean level of 3.9 +/- 1.5 mg/g). The amount of caffeine in the analyzed samples ranged from 7.5 to 86.6 mg/g, and the lower values were detected in green and oolong teas. This study will be useful for the appraisal of trace elements and antioxidant components in various teas, and it will also be of interest for people who like drinking this beverage.