紅茶タンニンの研究 : (其の2)紅茶タンニンの分別

概要

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By the oxidation of tea catechins on the black tea fermentation, black tea tannin is red and weekly astringent. On the two dimensional paper chromatogram of black tea tannin, some catechins, which have not been oxidized, and oxidized tannin are detected (Fig. 1), and it is, therefore. supposed that the black tea tannin contains not only oxidized tannin but also some unoxidized catechins. By the method of the counter current distribution, the black tea tannin is fractionated as follows; ether soluble (I) (unoxidized catechins) and ether insoluble but ethyl acetate soluble (II) (oxidized catechins) and ethyl acetate insoluble fraction (III) (polymerized tannin) (Fig. 2, 3). Of these three fractions, I and II are dialyzable but III is not (Fig, 4, 5). Several qualities of these fractions are detailed in Table 1 and fraction II has good color and taste. From the results of this experiments, it is supposed that the formation of black tea tannin is as follows: Tea catechins oxidation→ Primary products oxidation and→condensation Secondary products↓polymerization Polymers