Abstract: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. The highest 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 images revealed that TB particles with different molecular weights had different morphologies and the TB particles appeared as scattered 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 polymeric 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 products of the black precipitate obtained from the main fraction with molecular weight species between 3 500 and 25 000 Da.
Key words:Pu-erh tea;Theabrownin;Spectroscopic and structural characteristics
谭 超1,彭春秀2,高 斌1,龚加顺1* . 普洱茶茶褐素类主要组分特征及光谱学性质研究 [J]. 光谱学与光谱分析, 2012, 32(04): 1051-1056.
TAN Chao1, PENG Chun-xiu2, GAO Bin1, GONG Jia-shun1* . Spectroscopic and Structural Characteristics of the Main Components of Theabrownin in Pu-erh Tea . SPECTROSCOPY AND SPECTRAL ANALYSIS, 2012, 32(04): 1051-1056.
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