Dai Qianying, He Yuanyuan, Ho Chit-Tang, Wang Jing, Wang Shujuan, Yang Yue, Gao Liping, Xia Tao
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, 230036 Anhui China.
Department of Food Science, Rutgers University, 65 Dudley Road, New Brunswick, NJ 08901 USA.
J Food Sci Technol. 2017 Aug;54(9):2919-2928. doi: 10.1007/s13197-017-2730-5. Epub 2017 Jun 9.
Epigallocatechin gallate (EGCG) and flavonols are important phenolic compounds in green tea. These compounds are sensitive to thermal condition and their structural alteration results in making browning the green tea infusion. This study aimed to research the interaction between EGCG and flavonols during thermal infusion. EGCG and flavonols model solutions were prepared based on concentration in green tea infusion, and their colors appearance and attributes were analyzed in 10 h by thermal treatment. Results showed that kaempferol, quercetin, and myricetin accelerated the oxidation of EGCG and made the model solution browning. HPLC analysis revealed there was an obvious shift of a broaden peak in the mixed model solution of EGCG and flavonols after thermal treatment. This broaden peak was further purified on HPLC and solid phase extraction methods to yield colored complexes. The complexes showed the maximal absorption around 424, 442, and 482 nm. MS/MS analysis revealed that the complexes possessed of three components those were consisted of the interaction between EGCG and myricetin. These results indicated that the interaction between EGCG and flavonols might form complexes during thermal treatment, The complexes were contributed to make green tea infusion browning.
表没食子儿茶素没食子酸酯（EGCG）和黄酮醇是绿茶中的重要酚类化合物。这些化合物对热条件敏感，其结构改变会导致绿茶茶汤褐变。本研究旨在探究热浸过程中EGCG与黄酮醇之间的相互作用。根据绿茶茶汤中的浓度制备了EGCG和黄酮醇模型溶液，并通过热处理在10小时内分析了它们的颜色外观和属性。结果表明，山奈酚、槲皮素和杨梅素加速了EGCG的氧化，使模型溶液褐变。高效液相色谱（HPLC）分析显示，热处理后EGCG与黄酮醇的混合模型溶液中出现了一个明显变宽的峰的明显位移。通过HPLC和固相萃取方法对这个变宽的峰进行进一步纯化，得到了有色复合物。这些复合物在424、442和482nm左右显示出最大吸收。串联质谱（MS/MS）分析表明，这些复合物由三种成分组成，它们是由EGCG与杨梅素之间的相互作用形成的。这些结果表明，EGCG与黄酮醇之间的相互作用在热处理过程中可能形成复合物，这些复合物导致了绿茶茶汤的褐变。
