Dept. of Biological Sciences, Lehman College, Bronx, NY 10468, USA.
J Food Sci. 2010 Aug 1;75(6):C541-8. doi: 10.1111/j.1750-3841.2010.01705.x.
Recent investigations have associated white teas with anti-carcinogenic, immune-boosting, and antioxidative properties that may impact human health in a manner comparable to green teas. An in-depth chemical analysis of white tea types was conducted to quantify polyphenols and antioxidant potential of 8 commercially available white teas, and compare them to green tea. Extraction and HPLC protocols were optimized and validated for the quantification of 9 phenolic and 3 methylxanthine compounds to examine inter- and intra-variation in white and green tea types and subtypes. A sampling strategy was devised to assess various subtypes procured from different commercial sources. Variation in antioxidant activity and total phenolic content (TPC) of both tea types was further assessed by the 1-1-diphenyl-2-picrylhydrazyl (DPPH) and Folin-Ciocalteau (F-C) assays, respectively. Total catechin content (TCC) for white teas ranged widely from 14.40 to 369.60 mg/g of dry plant material for water extracts and 47.16 to 163.94 mg/g for methanol extracts. TCC for green teas also ranged more than 10-fold, from 21.38 to 228.20 mg/g of dry plant material for water extracts and 32.23 to 141.24 mg/g for methanol extracts. These findings indicate that statements suggesting a hierarchical order of catechin content among tea types are inconclusive and should be made with attention to a sampling strategy that specifies the tea subtype and its source. Certain white teas have comparable quantities of total catechins to some green teas, but lesser antioxidant capacity, suggesting that white teas have fewer non-catechin antioxidants present. Practical Application: In this investigation white and green teas were extracted in ways that mimic common tea preparation practices, and their chemical profiles were determined using validated analytical chemistry methods. The results suggest certain green and white tea types have comparable levels of catechins with potential health promoting qualities. Specifically, the polyphenolic content of green teas was found to be similar to certain white tea varieties, which makes the latter tea type a potential substitute for people interested in consuming polyphenols for health reasons. Moreover, this study is among the first to demonstrate the effect subtype sampling, source of procurement, cultivation, and processing practices have on the final white tea product, as such analysis has previously been mostly carried out on green teas.
最近的研究表明，白茶具有抗癌、增强免疫力和抗氧化的特性，可能会以类似于绿茶的方式影响人类健康。对 8 种市售白茶进行了深入的化学分析，以定量测定白茶和绿茶中的多酚和抗氧化潜力。优化和验证了提取和 HPLC 方案，以定量测定 9 种酚类和 3 种黄嘌呤化合物，以检查白茶和绿茶类型和亚型的内部和内部变化。设计了一种抽样策略来评估从不同商业来源采购的各种亚型。通过 1,1-二苯基-2-苦基肼（DPPH）和福林-科卡尔特（F-C）测定法分别评估了两种茶类的抗氧化活性和总酚含量（TPC）的变化。白茶的总儿茶素含量（TCC）范围很广，水提取物中从 14.40 到 369.60mg/g 干植物材料，甲醇提取物中从 47.16 到 163.94mg/g 干植物材料。绿茶的 TCC 也超过 10 倍，水提取物中从 21.38 到 228.20mg/g 干植物材料，甲醇提取物中从 32.23 到 141.24mg/g 干植物材料。这些发现表明，关于茶类中儿茶素含量等级顺序的说法尚无定论，并且应在采样策略中加以注意，该策略应指定茶类亚型及其来源。某些白茶的总儿茶素含量与某些绿茶相当，但抗氧化能力较低，这表明白茶中存在较少的非儿茶素抗氧化剂。实际应用：在这项研究中，白茶和绿茶以模拟常见茶制备方法的方式进行提取，并使用经过验证的分析化学方法确定其化学特征。结果表明，某些绿茶和白茶类型具有类似的儿茶素水平，具有潜在的促进健康的品质。具体而言，发现绿茶的多酚含量与某些白茶品种相似，这使得后者成为对健康有益的多酚有兴趣的人的潜在替代品。此外，这项研究是首次证明亚型采样、采购来源、种植和加工实践对最终白茶产品的影响的研究之一，因为以前这种分析主要是针对绿茶进行的。
