The aromas and more precisely the aromatic precursors primarily present in the skins are the principal compounds of interest.
Next come the anthocyanins which are present uniquely in the skins; and finally the tannins present in the skins and seeds. They have multiple forms and properties. Tannins play an essential role in the ageing of wines. The following tables summarize the properties of each component. Some studies are contradictory regarding the bitterness of tannins. The following properties are generally accepted:
4.1.5.a What compounds are of interest for extraction?
| | Oxygène | Amertume | Astringence | Autre |
|---|---|---|---|---|
| Tanins oligomères | Très réactif | Beaucoup | Beaucoup | |
| Tanins polymérisés | Peu réactif | Peu | Peu | |
| Tanins liés aux polysaccharides | Peu réactif | Aucune | Aucune | Gras et charnu |
| | Forme polymérisées % | Tanins associés aux polysaccharides % | Tanins oligomères % | Tanins astringents % | Réaction vis-à-vis de l’oxygène |
|---|---|---|---|---|---|
| Pellicules | 85 | 15 | 0 | 40 | Réaction lente et difficile |
| Rafles | 60 | 13 | 27 | 80 | Intermédiaire |
| Pépins | 40 | 5 | 55 | 80 | Réaction rapide et efficace |