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The grapes are first destemmed and crushed and a small amount
of sulphur dioxide is added to neutralize harmful bacterial ferments.
Then the must is transferred to a fermentation vat.
Fermentation is the transformation of the must into wine. Wine-yeasts convert sugar into alcohol and carbon dioxide, a process that takes five to ten days.
- Once fermentation begins, the carbon dioxide forces any solid matter into a compact mass, called the cap or marc, and brings it to the surface.
During vatting, "remontage" -pouring must over the cap- is repeated several times in order to homogenize and aerate the must, stimulating fermentation and promoting even diffusion of the colouring matter.
- Vatting requires careful and constant attention to temperature. The proper temperature for fermentation is around 30°C. Wines intended for a long period of aging must be tannic, and undergo a long maceration (two to three weeks; at 25° to 30°C).
On the other hand, red wines that are to be drunk while young (such as primeur wines) must be fruity and tannic. Their maceration is limited to a few days.
- During devatting the wine is run off and separated from the marc, the solid residue composed largely of seeds and skins.
Devatting takes place when most of the sugar content has been converted into alcohol.
The wine that is run off is known as "free-run" wine (vin de goutte or grand vin), as opposed to "press" wine, which is the liquid still remaining in the marc. The free-run wine is put into another vat to await the addition of the press wine.
- Once the free-run wine and the press wine have been thoroughly blended and allowed to settle, the mixture is racked off into casks for the final stages of fermentation.
These are the basic steps for wine-making, but other methods (thermovinification, continued vinification, carbonic maceration ) can be used.
- Once fermentation begins, the carbon dioxide forces any solid matter into a compact mass, called the cap or marc, and brings it to the surface.