Grapes

The clusters may be more or less voluminous, serrated or sparse, winged or half-winged, but they always consist of berries. They are placed on a small branch called a stalk or rachis that accounts for 3-5% of their weight. Rich in lignin and cellulose, the stalk contains a lot of water, resins and pectins, but mainly tannins and polyphenols. The tannins contained in the stalks, however, are short and simple molecules, poorly polymerised, which would give the wine a too hard and aggressive character as well as a strong sense of astringency. This is why the stalks are removed in the preliminary stage of vinification even in the production of red wine, with destemming carried out almost always before crushing.

The grape can be cone-shaped, oval, ellipsoidal, spherical and has different aromas and flavours and consists of skin, pulp and seeds. The least important elements are the pips, small seeds that account for about 5% of the weight, rich in woody and fatty substances. They have low polemirized tannins similar to those in the stalk, responsible for excessive astringency. The skin accounts for 10-15% by weight, but its composition is as important as that of the pulp. It contains water, pectins, cellulose, aromatic substances and polyphenols (decisive for the colour and tactile and gustatory characteristics of the wine). PRUIN: substance sometimes present on the skin that protects it from parasite attack, excessive heat and retains spontaneous yeasts.