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

Authors

  • Christopher Powell,

    1. Food Safety Research Group, School of Biological Sciences, University of Surrey, Guildford, Surrey GU2 5XH, UK
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  • Michael N. Clifford,

    Corresponding author
    1. Food Safety Research Group, School of Biological Sciences, University of Surrey, Guildford, Surrey GU2 5XH, UK
    • Food Safety Research Group, School of Biological Sciences, University of Surrey, Guildford, Surrey GU2 5XH, UK
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  • Shaun C. Opie,

    1. Campden Food and Drink Research Association, Chipping Campden, Gloucestershire GL55 6LD, UK
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  • Michael A. Ford,

    1. Smith Kline Beecham, The Royal Forest Factory, Coleford, Gloucestershire GL16 8JB, UK
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  • Alastair Robertson,

    1. Campden Food and Drink Research Association, Chipping Campden, Gloucestershire GL55 6LD, UK
    Current affiliation:
    1. Safeway plc, 6 Millington Road, Hayes, Middlesex UB3 4AY, UK
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  • Cohn L. Gibson

    1. Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, UK
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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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