Polyphenolics

What is there in wine? No-one knows exactly and ongoing research has identified over 600 components; there is some certainty, however, as regards the main factors responsible for the taste and color of the wine and these include the polyphenolics. The most important phenolics are the flavonols which account for the color of white wines, the catechins and the leucoanthocyans, which are responsible for instability in the color of white wines and the anthocyans for the red color.

These substances can react with acids in the wines, taking on more or less brilliant colors depending on the greater or lesser degree of acidity of the wine. They are also substances subject to oxidation, so the tone of the color of the wine can vary in depth, so that whites range from light yellow to brown, while reds vary from rosé to brown. The most important polyphenol is tannin. It comes from the skins, stalks and seeds, so it is present to a greater degree in red wines (between 1 and 5 parts per thousand), but in low quantities in whites or rosés which have had little contact with the skins and stalks (from 0.1 to 0.4 parts per thousand). Not all the tannins, however, have a positive influence on the wine; those of the pips, for example, are bitter and so it is advisable to use a press which does not break the pips.

It also depends on the grape variety. Certain varieties, usually those which are less highly prized, have acid, aggressive, sour tannins which have a negative influence on the taste and bouquet of the wine.

The best tannins, however, are the prerogative of the best cellars and are one of the most important elements in refining the taste of a wine. The higher the percentage of tannin the more sourness and roughness are accentuated and the taste is rather astringent. Tastes which, in the case of the best tannins, evolve over time, giving the wine the right balance, less astringency and a fuller taste and maintaining the red color in reds which are aged. The tannins serve an antibacterial role, protecting the wine and ensuring that it will have a long life.

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