Tea cream formation: The contribution of black tea phenolic pigments determined by HPLC

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Abstract
Reverse‐phase HPLC of liquors prepared from a Lattakari Assam black tea was used to assess the contribution of black tea phenolic pigments to ‘tea cream’, a precipitate which forms routinely following caffeine complexation of the phenols when a strong infusion of black tea cools. In this study caffeine was added back to tea liquor fractions and reconstituted decaffeinated whole tea liquor, and the extent to which the theaflavins, thearubigins and flavonol glycosides were removed from solution in the form of insoluble complexes was monitored by HPLC. The poorly characterised thearubigins are shown to be the principal (≈ 86%) pigmented phenolic components of ‘tea cream’. Theaflavins (≈ 12%) and flavonol glycosides (≈ 2%) were also present. Evidence is presented for a synergistic interaction between theaflavins and thearubigins during cream formation. The use of caffeine precipitation is proposed as an aid to the fractionation and quantification of phenols including thearubigins in black tea liquors.

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