摘要
利用不同分子截留量的透析袋可有效将茶褐素类物质分离。随分子量增大,茶黄素(TF)、茶红素(TR)、茶褐素(TB)、茶多糖(TPS)含量逐渐增加,分子量大于25 000Da的样品中TB含量最高。羧基和羟基含量随分子量增大而增加,特别是总羧基含量在分子量大于25 000Da的样品中增幅最大。AFM显示,不同分子量茶褐素粒子形貌并不均一,单分子呈岛屿状态或颗粒状聚集物结构。当粒子聚集较多时,呈线状链接且有较多分支或形成网状结构。CP-MAS NMR表明,在3 500～25 000Da的茶褐素属含有多苯环的苯多酚类高聚物,结合多糖、蛋白质残基,富含羧基、羟基、甲基等基团,具有酚类物质特性。其酸未水解物经CP-MAS NMR分析表明为多苯环高聚物,CP-GC/MS共鉴定出16种可能存在的化合物。
In the present study, we fractionated the main components of TB in Pu-erh tea by dialysis and investigated their compositions, structures and properties. TB in the Pu-erh tea was fractionated by dialyses using films with different pore sizes. Thehighest TB concentration was obtained in the fraction with molecular weight species 〉25 000 Da. The carboxyl and hydroxyl concentrations also increased in fractions where the molecular weight size selection was highest （i. e. , 〉25 000 Da）. AFM ima- ges revealed that TB particles with different molecular weights had different morphologies and the TB particles appeared as scat- tered islands or aggregates. CP-MAS NMR experiments revealed that the TB fraction with molecular weight species between 3 500 and 25 000 Da in size was characterized by a polymeric material of polyphenols. This pilyrnerie substance contained primarily multiple benzene rings, polysaccharides, protein residue groups and various other functional groups. After acidic hydrolysis, this fraction formed a black precipitate. CP-MAS NMR found that the precipitate was a polymeric material with multiple benzene rings. CP-GC/MS identified 16 candidate compounds from the pyrolysis produe_ts of the black precipitate obtained from the main fraction with molecular weight species between 3 500 and 25 000 Da.
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2012年第4期1051-1056,共6页
Spectroscopy and Spectral Analysis
基金
国家自然科学基金项目(30960241
30760152)资助
关键词
普洱茶
茶褐素
结构特征
光谱性质
Pu-erh tea
Theabrownin
Spectroscopic and structural characteristics
