The fermentation phase, corresponds in the wine-making sector, to the period during which the juice becomes wine. during approximatively 15 days, the sugar is turned into alcohol thank to the work of yeasts .

Indeed, the sugar bu being in contact with yeasts being on the skin of grapes or in the air, is turning into alcohol progressively. During the fermentation, other components will be released such as carbonic gas, alcohol, glycerol, which brings smoothness to the wine, the succinic acid, acetic acid, but as well aromatic components.

The fermentation keeps going until all the sugar has been turned into alcohol or until the level of alcohol in the juice rises up around 50%. At this level of alcohol, the yeast dies naturally and residual sugars will be kept in the wine.