Department of Chemistry, University of Warsaw, Warsaw, Poland.
J Sci Food Agric. 2012 Aug 30;92(11):2244-9. doi: 10.1002/jsfa.5611. Epub 2012 Feb 8.
Aromatised green teas are widely sold and popular owing to their fragrance. In this study the antioxidant activity of six commercial green tea infusions was assessed by three complementary assays.
In order to evaluate the tea infusions as antioxidant sources, their phenolic content (Folin-Ciocalteu assay), cupric ion-reducing antioxidant capacity (CUPRAC) and 2,2-diphenyl-1-picryhydrazyl (DPPH) radical-scavenging ability were determined. Their content of polyphenols was also determined by high-performance liquid chromatography/mass spectrometry (HPLC/MS) in negative electrospray ionisation mode. Some teas with citrus aroma, besides having a relatively high content of catechins, also contain other phenolic compounds such as naringin and hesperidin. The three assays used to evaluate the antioxidant capacity of the tea infusions gave different rank orders. Therefore an antioxidant index was calculated for better correlation of the results, and its highest value was obtained for Clear Green Mint tea infusion.
The studied teas, besides having a relatively high content of catechins, also contain naringin and hesperidin, which are not present in 'pure' green tea. It is important to run multiple assays to get a better estimate of the antioxidant capacity of a given sample.
调味绿茶因其香气而广受欢迎。在这项研究中，通过三种互补的方法评估了六种市售绿茶冲泡物的抗氧化活性。
为了评估茶冲泡物作为抗氧化剂的来源，测定了其酚类含量（福林-肖卡尔特法）、铜离子还原抗氧化能力（CUPRAC）和 2,2-二苯基-1-苦基肼（DPPH）自由基清除能力。还通过高效液相色谱/质谱（HPLC/MS）在负离子电喷雾模式下测定了它们的多酚含量。一些带有柑橘香气的茶，除了含有相对较高的儿茶素外，还含有其他酚类化合物，如柚皮苷和橙皮苷。用于评估茶冲泡物抗氧化能力的三种方法给出了不同的排序。因此，为了更好地关联结果，计算了抗氧化指数，其最高值为清爽薄荷绿茶冲泡物。
研究中的茶除了含有相对较高的儿茶素外，还含有柚皮苷和橙皮苷，而这些物质在“纯”绿茶中并不存在。为了更好地估计给定样品的抗氧化能力，运行多种测定方法非常重要。
