Vinification is adapted to the variety of wine we are looking for : red, white, rosé, dry or sweet, sparkling or still. But time is also key : sometimes less than two months for a fresh red wine, until two years and more for wines which are raised in oak barrels. A cellar master is in charge of all those processes. Chez Greg wants to to define you some essential notions to understand vinification and wine farming.
It is the transformation of grape’s sugar into ethanol thanks to yeasts. But others products appear, also important for flavours : esters, glycerol, carbonic dioxide…
Techniques change according the variety of wine
Red wine comes from maceration of solid parts of the grape (pips, skin of the grape…) in juice coming from scraped grapes. Winemaker keeps color, flavours and tannins.
White wine, most of the time, is only formed from the juice (not the solid parts) by direct pressing, then is clarified and fermented
Rosé wine is mixing the two last techniques. In fact, it can be produced :
- by bleeding : maceration like red ones, but juice and solid parts are early separated to get the wanted color.
- or by direct pressing like white ones, but with red grapes.
But other special wine-making techniques exist, like mutage (to stop fermentation),…
When vinification is over, wines are cloudy, full of carbonic dioxide. The cellar master has to be careful to clarify and stabilise them : this is the wine farming process. At the end of it, wine got its final style.
It can be realized :
- in vats : usually for younger wines
- in barrels : usually for wines to age
- or both can be used for the same wine
Role of sulfur
Sulfur additions protects against oxidization and bacteria without deteriorating the wine. But problems come from excess : too much sulfur causes headaches or allergies. That is why thresholds have been decided.
Organic vinification authorizes sulfur but with lower thresholds than in the conventional way. Wines without any sulfur also exist but are often more fragile.
To resume : three concepts to define a wine
- Color : white, red and rosé, obtained with different wine-making techniques
- Carbonic dioxide content : to distinguish sparkling and still wines
- Residual sugar content : to distinguish dry wines (sugar < 4 g/L) ; semi-dry (4-12 g/L) ; soft or « moelleux » (12-45 g/L) ; sweet or « liquoreux » (> 45 g/L)