Grapes grow in bunches of varying size, consistency and colour. The bunch has a stalk that makes up 3%-5% of its weight. For the purposes of winemaking, the grape has three essential components:
The skins (6%-10%)
The colour of a wine derives from the substances contained in the skins of the grape (yellow pigments are contained in both light and dark grapes; red pigments only in red grapes). The skins also contain tannins and yeasts, the mono-cellular fungi responsible for the fermention of grape juice.
The pulp (82%-90%)
The pulpy interior of the grape contains a juice composed of water, sugars, acids, mineral substances and vitamins.
The seeds (2%-4%)
The pips of the grape are rich in tannins and oils.