Sous Vide Crème Fraiche

Why This Recipe Works

Traditionally crème fraîche is often left to culture—for at least 12 and up to 24 hours—in a warm place. Culturing crème fraîche in a regulated water bath removes the need to manage (or worry about) the temperature of its surroundings during that critical phase. While yogurt is made by culturing milk, crème fraîche starts with heavy cream. For our recipe, we combined a small amount of buttermilk with pasteurized heavy cream, and then we placed this mixture in a warm water bath to culture for 12 hours. We strongly recommend using pasteurized—not ultra-pasteurized—cream for this recipe. Ultra-pasteurized cream is treated at a higher temperature before packaging and thus produces crème fraîche with a more muted flavor. Crème fraîche is a traditional accompaniment for luxurious caviar, or it can be served with fresh berries as an alternative to whipped cream. It's a favorite cultured dairy product to stir into hot braises and stews because, unlike sour cream or yogurt, crème fraîche won't curdle. Curdling occurs when cooking heat causes dairy proteins to denature and form clumps. The high butterfat content of crème fraîche (30 to 40 percent versus 18 to 20 percent of sour cream and roughly 4 percent of yogurt) protects against this clumping by keeping the proteins, which coat the many fat globules, further apart.