Wine Fermentation Explained: How the Process Affects the Flavor and Texture of Your Vino (Robb Report)
Wine has been made by humans for about 7,000 years, and experts agree that until quite recently it may not have tasted very good. For millennia wine has been the ultimate expression of agriculture, but once grapes are transported from the vineyard to the winery it is up to the winemaker to apply his or her hand to create the best beverage possible.
While cold fermentation is a relatively new technique, first introduced in the 1950s, many other practices are as old as winemaking itself. A lot of terms are casually tossed around by those in the know, so here is a quick explanation of some of the more common winemaking terms you may come across and how a wine is fermented will affect the final product.
Cold Fermentation
Wine, of course, is made by the process of fermentation: Yeast converts grape sugar to alcohol, and the end result is this glorious liquid we love. One of the byproducts of fermentation is heat, which left unchecked could cause temperatures to rise to the point that yeast dies and fermentation stops. Fermentation at higher temperatures can also create a wine with lighter aromatics, unpleasant flavors, and a lack of elegance or finesse.
A colder, slower fermentation preserves aromatics, fruit flavors and color. External cooling jackets or pipes filled with cold running water maintain temperatures within the tank, allowing the winemaker to control the speed of fermentation.
Barrel Fermentation
Wine may be fermented in a variety of containers, including stainless steel tanks, concrete vats or “eggs,” fiberglass tanks, terra cotta amphorae, or wooden barrels or vats. While stainless steel, concrete and fiberglass are considered neutral and do not impart flavor or texture to the contents within, fermenting in barrel adds flavor from the wood as well as a buttery or creamy texture.
This method leads to a richer mouthfeel and may bring flavors of vanilla, baking spice, coconut or coffee. It can be used for white wines such as Chardonnay or Verdejo as well as red wines like Cabernet Sauvignon, Merlot, Nebbiolo, or Tempranillo.