Black tea thearubigins—their HPLC separation and preparation during in‐vitro oxidation

Abstract A reverse phase, gradient elution HPLC method has been developed to separate black tea thearubigin compounds. Using diode array spectroscopy, spectral data are provided for the major pigment peaks. The analytical method has been used to monitor the formation of the thearubigin compounds during black tea fermentation. In‐vitro model fermentation systems using partially purified tea polyphenol oxidase and mixtures of six pure catechins have also been analysed. Data are presented to relate many of the thearubigins in black tea liquors to their catechin precursors. Manipulation of the in‐vitro model system conditions will be used to prepare various thearubigins for further structural studies.