Different kinds of thickening agents can be used in preparing sauces. Choosing the right type is critical.
Thickening agents, based on the gelatinization of starch, include Roux (a cooked mixture of equal parts melted butter and flour), uncooked Roux (otherwise known as a beurre manie, also equal parts butter and flour, which are kneaded together before being added), Arrowroot (a paste made from the roots of a tropical plant, providing a clear and stable solution) and Corn Starch Slurry (a paste made of corn flour and water, after which it is added to a boiling sauce).
Thickening agents, based on other methods include what is known as Reduction (the process of removing liquid from a sauce by applying heat and releasing steam), Liaison (prepared by mixing heavy cream and eggs, resulting in a smooth and creamy texture), Food Grade Gums (purpose produced agents that do not alter a sauce’s flavour or texture) or Puree (whereby finely mashed fruit or vegetables are added to the sauce).