The starchy product of a tropical tuber of the same name. The rootstalks are dried and ground into a very fine powder. Arrowroot is used as a thickening agent for puddings, sauces and other cooked foods, and is more easily digested than wheat flour. Its thickening power is about twice that of wheat flour. Arrowroot is absolutely tasteless and becomes clear when cooked. Unlike cornstarch, it doesn't impart a chalky taste when undercooked. It should be mixed with a cold liquid before being heated or added to hot mixtures. Some English and early American cookie recipes call for arrowroot flour, which is the same product. Arrowroot can be found in supermarkets, health-food stores and Asian markets.