When making white wines, the juice is separated from the grape skins immediately after the clusters have been crushed and destemmed, then it heads to fermentation. Skins can impart color and tannin that would overwhelm the white wine’s characteristically delicate flavors.
Yeasts are added to start the fermentation process, turning the juice’s sugar into alcohol. Vintners can then choose a number of paths to create the type of wine they desire. In fact, different winemaking practices can produce dramatically different wines from the same grape. For instance, wines can be fermented and aged in oak barrels, stainless steel tanks or a combination of both, all of which result in different flavors and characteristics. Fermentation, which is typically finished when the wine is “dry” (i.e. not sweet), can last anywhere from three days to three weeks.
In California, some varieties, particularly chardonnay, are allowed to sit on their lees (or spent yeast cells), which can give the wine a richer texture and often times greater complexity. Some vintners employ a secondary fermentation known as malolactic fermentation, which converts the wine’s malic acid to lactic acid, softening the wine and often giving an impression of “butteriness.”