• bitterness;
  • astringency;
  • 3R(−)-epicatechin;
  • 3S (+)-catechin;
  • time-intensity;
  • phenolics


Bitterness and astringency of the monomeric flavan-3-o!s ( + )-catechin and (−)-epicatechin were rated using time-intensity (T-I) methodology. Three concentration levels (0.5. 0.9 and 1.2 g liter−1) oi each compound were assessed, and the parameters time to maximum intensity (TMAX), intensity at the maximum (IMAX) and total duration (TTOT) were extracted from the T-I curves. No differences in TMAX for either bitterness or astringency were found between these chiral isomers or as a function of concentration within a compound. Epicatechin had a significantly 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 significant at one concentration. Astringency TTOT was longer for epicatechin, although this was nonsignificant at the lowest concentration. The three concentrations of catechin were significantly different for both bitterness and astringency IMAX and TTOT. Epicatechin showed evidence for the astringency response plateauing above the 0.9 g litre−1 level. n-Propylthiouracil status had no effect on perception of either bitterness or astringency.