Urban Platter Arrowroot Powder, 150g, Arrowroot thickens at lower temperatures unlike thickeners made with flour or cornstarch. It can be used in place of flour or cornstarch in various recipes. 1 tsp of arrowroot can be substituted for 1 tbsp of flour, and 2 tsp of arrowroot can be substituted for 1 tbsp of cornstarch. Lack of gluten in arrowroot flour makes it useful as a replacement for wheat flour in baking.