The phenolic pigment composition of black tea liquors—part I: Predicting quality

Abstract

AbstractThe phenolic constituents of 95 black teas, representing nine countries, were analysed and assessed by HPLC. The procedure resolved 38 coloured phenolic components which were classified as theaflavins (4), thearubigins (23) and flavonol glycosides (11). The relative levels of these constituents were monitored by HPLC. One of the thearubigin constituents was unresolved chromatographically, but nevertheless quantified as a hump. The data set was statistically analysed using principal component analysis (PCA) and multiple regression PCA indicated that three of the quality attributes, quality/flavour, brightness/briskness and quality with milk, were strongly correlated with each other. The fourth attribute, colour/strength, was found to be the most effective in discriminating between teas, particularly between high strength teas from Assam and Tanzania and low strength teas from Sri Lanka and Malawi. Multiple regression was used to investigate the relationship between tasters' scores and the chemical constituents. The model established gives an R2 of 63% based on six components; five resolved thearubigins and the unresolved thearubigin hump. These results indicate the potential to develop objective chemical assessment procedures for determining the quality of teas and is the first report of the flavour impact of individual thearubigins constituents.