How to Thicken a Sauce

The creation of sauces, like all things culinary, began with French chefs. Today, a wide variety of thickening agents are still used with almost every sauce created, that is, unless the sauce in question is intended to be a jus. In fact, the main difference between a sauce - a liquid dressing or topping - and a jus - the juices from roasting - comes down to the use of thickening agents. Typically, which thickening agent chosen depends on the final usage, taste, and texture of the sauce required by a recipe.

By far, the most popular thickening agent remains the roux, a classic thickener used in white, blond, or brown versions. A roux is nothing more than a cooked mixture of flour and fat (traditionally clarified butter) that is used to thicken a soup or sauce. The color of the roux also dictates the intensity of flavor created such as with béchamel sauce, which is achieved with a barely-cooked white roux and a bit of nutmeg; sauce veloute, made with chicken stock and a blond roux that has a hint of nutty aromas; and gumbo, which is made with a deeply nutty and well-cooked brown roux.

As an alternative to using a roux, other options include using a slurry - a mixture of cornstarch and water that is added while cooking - or a beurre manie - a mixture of raw flour and soft butter that is not cooked as a roux, but rather, is simply added while cooking. Two other ways of thickening a sauce are to use a liaison, which is a mixture of cream and eggs, or a simple reduction, which relies not on adding something, but instead, allows the sauce to thicken on its own through the reduction of water that is within the sauce itself.