Sensory variability associated with anthocyanic and tannic fractions isolated from red wines

Tannins and anthocyanins are important modulators of the intrinsic quality of red wines, playing a major role in consumer preference and appreciation. Tannins are chiefly responsible for the astringency in wines although their role in eliciting different astringent subqualities is still relatively unknown. On the other hand, the sensory contribution of anthocyanic fractions is even less clear. The main aim of the present study was to assess whether anthocyanic fractions from red wine elicit specific mouthfeel and taste attributes that differ from their tannin counterparts, and to evaluate the contribution of anthocyanic and tannic fractions to taste and mouthfeel of red wines. Isolation of tannin (F_tannin) and anthocyanin (F_antho) fractions from 20 wines involved reversed-phase semipreparative liquid chromatography followed by solid phase extraction. The 40 derived fractions subsequently underwent sensory characterisation using a labelled sorting task and a rate-K attributes method. Bitterness and dryness were the salient attributes differing among the sensory spaces of both F_antho and F_tannin. Likewise, other independent and non-correlated mouthfeel dimensions differed for both F_antho ("grainy" and mouthcoating") and F_tannin ("gummy"). A significant linear model predicting wine dryness from the "dry" intensity of F_antho and F_tannin was obtained, with tannic fractions presenting a higher contribution than anthocyanic fractions. These results not only confirmed that tannins have a major implication in red wine dryness but also unequivocally demonstrated a relevant implication of certain anthocyanins in this attribute. In contrast, bitterness of the original wines could not be directly related to the bitterness perceived in any of the two groups of fractions. The addition of an extremely bitter anthocyanic fraction to wines only increased bitterness in certain wines, suggesting that bitterness in wines may result from perceptual interactions and that some wines contain strong bitterness suppressors.