Paiva Lisete, Rego Clara, Lima Elisabete, Marcone Massimo, Baptista José
Chemistry and Engineering (DPCE) and Biotechology Centre of Azores (CBA), Department of Physics, University of Azores, 9500-321 Ponta Delgada, São Miguel, Azores, Portugal.
Institute of Agricultural and Environmental Research and Technology (IITAA), University of Azores, 9700-042 Angra do Heroísmo, Terceira, Azores, Portugal.
Antioxidants (Basel). 2021 Jan 27;10(2):183. doi: 10.3390/antiox10020183.
This study evaluates the polyphenol profiles as well as caffeine (dry weight basis), and antioxidant activities of green tea (GTs), white tea (WTs), and flowers (Fl) samples from Azorean varieties affected by different harvested and processing conditions. Epicatechins derivatives, determined by RP-HPLC/PDAD, presented higher values in GTs with respect to WTs, decreasing as follows: epigallocatechin-3-gallate > epicatechin-3-gallate ≫ epicatechin ≫ epigallocatechin, and higher values in summer and early autumn than in spring. This was also accompanied by an in consistent withering time pattern. Esterified catechins were higher in all samples (100.8-312.3 mg/g) with respect to non-esterified catechins (15.1-37.7 mg/g). Caffeine (6.2-27.7 mg/g) decreased as follows: WTs > GTs ≫ Fl, and inconsistent seasonal and withering patterns were observed among the WTs. Total phenolics (125.9-295.4 mg gallic acid equivalents/g dried extract) and total flavonoids (35.2-69.7 mg rutin equivalents/g dried extract), determined by Folin-Ciocalteu and colorimetric methodologies, were higher in GTs than in WTs and Fl. Concerning the antioxidant patterns, the free radical scavenging activity (FRSA) and ferric reducing antioxidant power (FRAP) presented EC values ranges from 3.6 to 17.3 µg/mL and 4.8 to 16.5 µg/mL, respectively, and ferrous ion-chelating (FIC) activity ranged from 47.1 to 82.8%, highlighting that FRSA was better than butylated hydroxytoluene (BHT). Tea leaves exhibited, in general, higher activities with respect to tea Fl, and the WT sample plucked in summer and withered for 23 h showed the highest FRAP and FIC activity. In conclusion, this study shows the characteristic variation of GTs, WTs, and Fl of two tea varieties and may support crop quality improvement and promote the valorization of tea Fl.
本研究评估了受不同采收和加工条件影响的亚速尔群岛品种绿茶（GTs）、白茶（WTs）和茶花花（Fl）样本中的多酚谱、咖啡因（以干重计）及抗氧化活性。通过反相高效液相色谱/光电二极管阵列检测法（RP-HPLC/PDAD）测定的表儿茶素衍生物，在GTs中的含量高于WTs，其含量递减顺序如下：表没食子儿茶素-3-没食子酸酯＞表儿茶素-3-没食子酸酯≫表儿茶素≫表没食子儿茶素，且在夏季和初秋时的含量高于春季。这还伴随着不一致的萎凋时间模式。所有样本中酯化儿茶素（100.8 - 312.3毫克/克）的含量均高于非酯化儿茶素（15.1 - 37.7毫克/克）。咖啡因含量（6.2 - 27.7毫克/克）递减顺序如下：WTs＞GTs≫Fl，且WTs中观察到不一致的季节和萎凋模式。通过福林-西奥尔特法和比色法测定的总酚（125.9 - 295.4毫克没食子酸当量/克干提取物）和总黄酮（35.2 - 69.7毫克芦丁当量/克干提取物），在GTs中的含量高于WTs和Fl。关于抗氧化模式，自由基清除活性（FRSA）和铁还原抗氧化能力（FRAP）的EC值范围分别为3.6至17.3微克/毫升和4.8至16.5微克/毫升，亚铁离子螯合（FIC）活性范围为47.1%至82.8%，突出表明FRSA优于丁基羟基甲苯（BHT）。总体而言，茶叶的活性高于茶花，夏季采摘并萎凋23小时的WT样本表现出最高的FRAP和FIC活性。总之，本研究展示了两个茶品种的GTs、WTs和Fl的特征变化，可能有助于提高作物品质并促进茶花的价值提升。
