SENSORY EVALUATION OF BITTERNESS AND ASTRINGENCY OF 3R(-)-EPICATECHINAND 3S(-CATECHIN())

Bitterness and astringency of the monomeric flavan-3-ols (+)-catechin and (-)-epicatechin were rated using time-intensity (T-I) methodology. Three concentration levels (0.5, 0.9 and 1.2 g liter(-1)) of each com pound were assessed, and the parameters time to maximum intensity (TMA X), intensity at the maximum (IMAX) and total duration (TTOT) were ext racted from the T-I curves. No differences in TMAX for either bitterne ss or astringency were found between these chiral isomers or as a func tion of concentration within a compound. Epicatechin had a significant ly higher bitter IMAX than catechin at all three concentration levels, and had a significantly longer TTOT at the two higher concentrations. Epicatechin was more astringent than catechin, but this was only sign ificant at one concentration. Astringency TTOT was longer for epicatec hin, although this was nonsignificant at the lowest concentration. The three concentrations of catechin were significantly different for bot h bitterness and astringency IMAX and TTOT. Epicatechin showed evidenc e for the astringency response plateauing above the 0.9 g litre(-1) le vel. n-Propylthiouracil status had no effect on perception of either b itterness or astringency.