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Alcoholic fermentation

Fermentation is the transformation of sugar into alcohol by yeasts.
Alcoholic fermentation causes a rise in temperature and produces carbon dioxide.
At the end of the alcoholic fermentation, the grape juice becomes the new wine.

The fermentation can be total, the wine is then said to be “dry” or “without residual sugars”.
If the fermentation is partial, the wine is then “mellow”, “sweet”, or “syrupy” in ascending order of quantity of unfermented sugars.

During vinification, the cellar master monitors many parameters on a daily basis, in particular :

  • the temperature, which must be favorable to the development of the yeasts and allow a soft extraction of the tannins,
  • the density, which makes it possible to follow the evolution of the fermentation thanks to the mustimeter also called densimeter.

A daily tasting of each vat allows us to adjust the winemaking parameters (temperature, intensity of pumping over for the reds) and to make sure that there are no defects.

 

 Courbe de fermentation : évolution de la densité et de la température

An example of a fermentation monitoring curve in 2019