So the grapes have been harvested and crushed, the final few steps in our series tell about how our favorite beverage is produced.
Fermentation is the age-old process of yeast converting sugar-laden grape juice into wine. Because of the myriad grape varieties that are grown, and the drive by winemakers to craft the finest wines in the world, fermentation techniques abound. With white wines, Chardonnay is often barrel fermented and goes through malolactic fermentation to create complex, creamy notes. Sauvignon Blanc and other light white varieties are fermented at cool temperatures in stainless steel to preserve primary fruit aromas and crisp acidity. Pinot Noir will typically sit on its skins for a few days before fermentation in a “cold soak” to extract more color from this thin-skinned, red variety. Cabernet Sauvignon and other high tannin red grape varieties, like Syrah and Petite Verdot, often spend time on their skins after fermentation to soften the tannins and create deeper color and a denser mouth feel in the resulting wine.
During the aging of their wines, winemakers use a wide spectrum of techniques to allow flavors to develop over several months or even a couple of years. Decisions on the use of stainless steel or French or American oak, the toasting level of the wood barrels, how to strike the balance between the stronger character of new oak versus the more neutral nature of previously used barrels, and innovative techniques such as aging in concrete vessels shaped like eggs, all affect the flavor of the final wine.
Determining when to bottle a wine is a very personal decision for the winemaker and is highly dependent on the vintage and character of the wine. For a light white wine like Riesling, it may require no further thought than allowing the wine to stabilize in the tank for a few months after fermentation. In contrast, for a barrel-fermented Chardonnay, a period of lees stirring in barrel over the course of a year might precede a settling period before bottling. For red wines, aging wine in oak for 18-24 months is not uncommon, and allows complex flavors and aromas to develop in the wine.