Natural starch for thickening sauces. Steenbergs Arrowroot is a dry white powder of almost pure natural starch. Arrowroot is a neutral tasting and inodorous powder and used as a thickening agent for gravies, casseroles and jellies. It thickens at a lower temperature than flour or cornstarch to a perfect gel and is less likely to become sour during digestion than farinaceous foods, so is good for the sick and delicate.