Taste and mouth-feel properties of different types of tannin-like polyphenolic compounds and anthocyanins in wine

The taste and mouth-feel properties of three different types of tannin-like polyphenolic compounds, representative of some of the tannin-like polyphenolic compounds found in red wines, were determined using descriptive sensory analysis. Ethyl-bridged flavanols were produced by reaction of (+)-catechin with acetaldehyde under acidic conditions. Red coloured tannin-like polyphenolic compounds from wine and from wine pomace were isolated by multi layer coil counter-current chromatography (MLCCC). Mouth-feel attributes and bitterness of the fractions dissolved in a model wine (MW) medium were rated while the fractions were held in the mouth and after expectoration. The sensory properties of the fractions described above were compared to those of apple procyanidins (tannins) with degree of polymerisation (dp) 3 and 9. Both wine and pomace-derived coloured tannin-like polyphenolic compounds were rated as significantly less astringent when compared to both the apple tannin fractions but were similar to the MW. The ethyl-bridged flavanols (with mean dp of 5) were rated significantly more bitter than both the apple procyanidin fractions. Astringency of the ethylbridged flavanols was lesser than the apple procyanidin fraction with dp9 and more than that with dp3. Highly purified grape anthocyanidin monoglucosides and monoglucoside coumarates, prepared either by solid-phase extraction or by multi layer coil counter-current chromatography were rated similarly to the MW indicating that free anthocyanins, like the coloured tannin-like polyphenolic compounds from wine and pomace, do not contribute astringency nor bitterness to wine.