Department of Tea Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China.
Department of Tea Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China.
Food Res Int. 2022 Aug;158:111542. doi: 10.1016/j.foodres.2022.111542. Epub 2022 Jun 21.
Green tea cream, the precipitate formed in cooled green tea infusion, appears a negative effect on flavor. To explain the mechanism of green tea cream, complexations between four catechins (CATs) and caffeine (CAF) were engineered and characterized. Dynamic light scattering, high performance liquid chromatography, scanning electron microscopy, fourier-transform infrared spectroscopy, UV-visible absorption spectrum, and x-ray diffraction were used to reveal the differences between ester catechins and non-ester catechins in the dynamic complexation process, particle shape, and precipitate mechanism with caffeine. The results indicated that CATs and CAF affected each other's microenvironment in aqueous solution and Guanidine hydrochloride (GH) weakened the effect both in solution and precipitate. In addition, the 1:1 complex structure of EGC-CAF was first proved, the hydrogen bond, CH…π and π…π interaction were the forces of CAT-CAF complexes by XRD. These results provided a new perspective to the mechanism analysis of green tea cream.
绿茶乳，是冷却后的绿茶浸提液中形成的沉淀物，对风味有负面影响。为了解释绿茶乳的形成机制，对四种儿茶素（CATs）和咖啡因（CAF）之间的络合作用进行了设计和表征。采用动态光散射、高效液相色谱、扫描电子显微镜、傅里叶变换红外光谱、紫外-可见吸收光谱和 X 射线衍射研究了酯型儿茶素和非酯型儿茶素在动态络合过程、颗粒形状和与咖啡因沉淀机制中的差异。结果表明，CATs 和 CAF 在水溶液中相互影响彼此的微环境，盐酸胍（GH）在溶液中和沉淀中均减弱了这种影响。此外，首次证明了 EGC-CAF 的 1:1 络合结构，通过 XRD 证实了氢键、CH…π 和 π…π 相互作用是 CAT-CAF 络合物的作用力。这些结果为绿茶乳的形成机制分析提供了新的视角。
