Separation and classification of the brown pigments of aqueous infusions of black tea

Abstract

Rapid thin‐film counter‐current dialysis of a typical infusion of black tea indicates that 10–12% of the soluble solids are non‐dialysable. the major components of this fraction are polysaccharides and a complex mixture which could not be separated into its protein and polyphenolic constituents. This latter complex accounts for 30–40% of the colour (E450) of the infusion. Solvent extraction of the infusion followed by dialysis of the various extracts reveals that the polyphenol‐protein complex may be approximately equated with ‘SII thearubigins’. Chromatography of infusions and various extracts thereof on alkylated Sephadex allows a partial separation of the coloured components largely owing to differences in molecular size. At least 7 distinct zones can be recognised.

Chemical characterisation of CTC black tea of northeast India: correlation of quality parameters with tea tasters' evaluation

“…When flavour is not an important factor, tea quality is positively related to TF content, which imparts the brightness of the liquor and the tone of the colour with milk 10. TR content also makes an important contribution to the total colour and its depth as well as the strength and mouthfeel of the tea liquor 12, 40, 41…”

“…Although there are contradictory views on the desirable level of CA (concerning health and benefit), according to Roberts and Smith,18 the briskness of tea infusion can be enhanced by increasing TF and CA levels. CA combines with oxidation products of polyphenols and determines the creaming properties of tea 41…”

Cream formation in a semifermented tea

“…Millin et al 21 showed that 7% of endogenous polysaccharides, especially polygalacturonic acid, took part in cream formation in black tea by forming loosely bound complexes with polyphenolic and proteinaceous materials. Although there is little information concerning the af®nity between polyphenols and polysaccharides, the complexation of pectin and other constituents is less important in cream formation in Paochung tea, because its presence was relatively low (2%) in the cream.…”

Nonvolatile components of black tea and their contribution to the character of the beverage

“…Nondiaiyzable Fraction. By employing the technique of thin film countercurrent dialysis (Craig and Stewart, 1965), we have shown that some 10 to 12% of the soluble solids of tea are nondiaiyzable (Millin et al, 1969). It includes the polysaccharide material mentioned above (34% by weight), smaller amounts of protein (6%) and nucleic acid (ca.…”