The polyphenols are support molecules of the principal organoleptic properties of the wines.They are widely present in the wine, more present in the red wines than in the white . One finds them :
Tannins, in charge of the gustatory properties.
Astringency is due to tannins catechins (natural antioxidant phenol) which precipitate salivary proteins, involving this feeling of oral drought ;
Anthocyanins, these red pigments responsible for the color of the wine; flavones, these yellow dyes which give their color to the white wines.
These phenolic compounds come from the solid parts of grape, strips and pips. They are extracted during fermentation and from the maceration. More the grapes are mature, fresh and lively, and more they contain molecules interesting for the structure of the wine with consequently, more qualities. The polyphenols which are in general rather fragile, are preserved relatively well during the vinification. One especially finds them significantly amount in the red wines where them concentration can vary according to type of vine. Natural and organic red grapes are the bests !