Inarejos-Garcia Antonio M, Heil Julia, Guilera Bermell Sonia, Morlock Gertrud E
Department of Functional Extracts, ADM® Wild Valencia, 46740 Carcaixent, Spain.
Institute of Nutritional Science, Chair of Food Science and TransMIT Center for Effect-Directed Analysis, Justus Liebig University Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany.
Antioxidants (Basel). 2023 Dec 15;12(12):2121. doi: 10.3390/antiox12122121.
Commercially available tea extracts for dietary supplements and nutraceuticals are standardized to characteristic components of L., such as epigallocatechin gallate (EGCG) and total catechins or polyphenols. However, since most commercial tea extracts are highly concentrated into only one molecule such as EGCG, the comparatively less stable catechin, the oxidative stability of the extract during the 24-month shelf life was questioned. It was hypothesized that the overall oxidative stability is reduced for highly purified/concentrated tea extracts due to the absence of other natural antioxidants stabilizing the complex mixture. Via liquid chromatographic analysis, the individual chromatographic profiles of 30 commercial white, green, and black tea extracts were evaluated and compared regarding oxidative stability and functional properties. The contents of bioactive flavan-3-ols, theaflavins, and methylxanthines differed much from what was claimed by the suppliers. At the end of the product shelf life, most of the commercial green and black tea extracts showed a decrease in the flavan-3-ol content, the main bioactive components of tea. A high EGCG content to the detriment of other possibly stabilizing flavan-3-ols or antioxidants in tea was found to explain the lower oxidative stability of such tea extract products. A natural overall composition of molecular structures was found to be superior to a strong enrichment in just one molecule.
用于膳食补充剂和营养保健品的市售茶提取物是根据茶（L.）的特征成分进行标准化的，如表没食子儿茶素没食子酸酯（EGCG）以及总儿茶素或多酚。然而，由于大多数市售茶提取物高度浓缩为仅一种分子，如相对不太稳定的儿茶素EGCG，因此有人质疑该提取物在24个月保质期内的氧化稳定性。据推测，由于缺乏其他稳定复杂混合物的天然抗氧化剂，高度纯化/浓缩的茶提取物的整体氧化稳定性会降低。通过液相色谱分析，评估并比较了30种市售白茶、绿茶和红茶提取物的各自色谱图，以研究其氧化稳定性和功能特性。生物活性黄烷-3-醇、茶黄素和甲基黄嘌呤的含量与供应商所宣称的有很大差异。在产品保质期结束时，大多数市售绿茶和红茶提取物中的黄烷-3-醇含量下降，而黄烷-3-醇是茶的主要生物活性成分。研究发现，高EGCG含量以牺牲茶中其他可能具有稳定作用的黄烷-3-醇或抗氧化剂为代价，这可以解释此类茶提取物产品较低的氧化稳定性。分子结构的天然整体组成被发现优于仅一种分子的强烈富集。
