Which two starch-based thickening methods are commonly used in sauce preparation?

• A. Reduction and emulsification
• B. Beurre monté and beurre manié
• C. Roux-based sauces and cornstarch/arrowroot slurries
• D. Gelatinization and foaming

Answer: (C)

When thickening sauces with starch, the goal is to make starch granules swell and trap liquid as heat is applied, a process called gelatinization. The two most common ways to achieve this in sauces are by using a roux or by making a starch slurry.

A roux is flour cooked in fat (like butter or oil) to a chosen color, then liquid is whisked in to form a thick, smooth sauce. The fat-flour blend coats the starch and helps control the thickening, adding body and flavor that varies with how long the roux is cooked. This method provides a reliable base for many classic sauces.

A slurry combines starch—usually cornstarch or arrowroot—with cold water or another cold liquid, then this mixture is whisked into a hot sauce and heated until thickened. Cornstarch gives a glossy finish and strong thickening, while arrowroot tends to be clearer and works well with acidic ingredients.

Reduction thickens by evaporating water, not by starch; foaming and emulsification rely on other mechanisms rather than starch gelatinization. Beurre manié or beurre monté involve butter and flour or fat emulsions to adjust texture, but the standard starch-based thickening methods most commonly used are roux-based sauces and starch slurries.