In culinary terms, what is a roux primarily used for?

Roux is primarily used as a thickening agent in cooking. It is a mixture of fat and flour that is cooked together to create a paste, which can then be added to soups, sauces, and gravies. When the roux is cooked, the flour undergoes a process called gelatinization, where the starches absorb liquid and swell, resulting in a thicker consistency once incorporated into a dish. This thickening property is essential in many classic sauces, such as béchamel and velouté, as well as in dishes like gumbo.

In contrast, while roux can contribute some flavor to a dish, its main purpose clearly lies in thickening rather than enhancing flavor. Cooking oil does not have the same properties as roux and is primarily used for frying or sautéing, while garnishes serve only to add visual appeal or a final touch to a dish, not to alter its consistency or texture.