The pigments which ensure the colour of red wines, also in terms of intensity and tone, are the anthocyanins derived from the grapes and the resulting products formed from reactions, during the vinification. With the exception of the grape varieties said to be “teinturiers”, the anthocyanins are located in the vacuoles of the cells making up the grape berry skin.
The tannins, which play a role in the stability of this colour, are found mainly in the seeds and skins. Recent studies by the INRA indicate the presence of tannins in low concentrations even in the pulp.
Since the compounds responsible for the colour are localized in the cells of the skin, the vinification and the choice of the techniques applied aim to open a path for the passage through the pulp. In fact, no extraction is possible through the “pruine”.
The temperature is a predominant physical factor but indirectly. It intervenes to favourize or create the extraction conditions by weakening the various elements which assure the resistance of the grape berry cells.
