This is the process of fermenting grape juice in a large oak barrel instead of a stainless steel tank. Barrel fermentation is especially utilized with white wines. And as is often the case with Chardonnays, a winemaker may choose to ferment half of its pressed juice in an oak barrel and half in a stainless tank. Because white wines don’t have the tannic acids found in red wine, barrel fermenting the wine allows the tannic acid from the wood barrels to leach into the wines. This gives the “full mouthfeel” that Brynn loves so much in her Chardonnay.