What is commonly used as a thickening agent for sauces?

Cornstarch is a widely recognized thickening agent for sauces due to its ability to absorb liquid and swell when heated. When mixed with a cold liquid to create a slurry before being added to a hot mixture, cornstarch helps to thicken sauces efficiently by forming a stable gel-like consistency. This process works through the starch granules absorbing water and gelatinizing, which enhances the texture of the sauce without altering its flavor significantly.

Other ingredients like gelatin can provide thickness but are more suited for specific applications, such as desserts or aspics, as they require cooling to set. Brown sugar imparts sweetness and color rather than serving as a thickener, while nutmeg is a spice used to enhance flavor, not texture. Cornstarch's clarity and ability to create a smooth consistency make it the preferred choice for many culinary applications requiring thickening.