Crème fraîche is a matured, thickened cream in which lactic acids and naturally occurring bacteria have been allowed to slowly develop a slightly tangy, nutty flavor and velvety rich texture.
French for “fresh cream,” crème fraîche is thought to have originated in Normandy and is used lavishly in sauces, drizzled over vegetables and spooned on fresh fruit. Its texture can range from that of sour cream to become almost as solid as room-temperature butter. Today, crème fraîche is still a specialty item, but is available in many U.S. food shops and specialty grocers.
To make crème fraîche, the cream is pasteurized and then seeded with a starter culture, much the way yogurt and cheese are made. The cream is then left until slightly soured and thick.
Crème fraîche is the ideal addition for sauces or soups because it can be boiled and reduced without curdling. Its tangy flavor and luxurious texture adds acidity and richness to sauces, desserts and baked goods. Crème fraîche is less acidic than buttermilk, yogurt and sour cream, is not as standardized as most other commercial dairy products, and will have the fat content of the cream from which it is made. In general, crème fraîche and sour cream can be used interchangeably in most recipes, but crème fraîche will not curdle if boiled and can be whipped.
Herbst, Sharon Tyler. Food Lover’s Companion, Third Edition. New York: Barron’s, 2001
McGee, Harold. On Food and Cooking. New York: Scribner, 2005