If you’ve ever read recipes that are plant-based, and gluten- or dairy-free, odds are you’ve seen the ingredient arrowroot starch. Often listed as a substitute for cornstarch, arrowroot starch is a thickening agent used in cooking and baking. Also known as arrowroot powder, it's neutrally flavored and works well in sauces, soups, and baked goods.
Most commonly obtained from the tropical plant Maranta arundinacea, arrowroot starch is native to Guyana and western Brazil and cultivated throughout parts of the Caribbean, Southeast Asia, Australia, and South Africa. To process arrowroot starch, the plant is harvested in its rootstock form, washed, peeled, and grated into a liquidy pulp. It is then dried and washed several more times to ensure it is pure. By the time it reaches consumers in the grocery store it is a fine, bright white powder that looks like cornstarch.
Since arrowroot starch is easily digested, it's often used over cornstarch by people who follow certain diets. Its extremely fine texture is more quickly absorbed by liquid, and therefore makes it a good choice when thickening a very delicate recipe, like a fruit sauce. While it will work beautifully in thickening ice cream too, arrowroot starch can turn slimy when cooked with other forms of dairy. It holds up more strongly than cornstarch in highly acidic recipes
Arrowroot starch (as well as cornstarch, tapioca starch, and potato starch) are often called for in gluten-free recipes along with gluten-free flours like rice, almond, chickpea, and coconut. Using a ratio of 1 part starch to 2 parts flour is the best way to make a gluten-free baked good mimic the texture of the real deal.
While arrowroot starch shouldn’t be substituted completely for flour in baked goods for flavor purposes, it can be used instead of flour to thicken sauces, soups, and gravies at a ratio of 1 teaspoon arrowroot for 1 tablespoon cornstarch. If you’d like to use arrowroot starch as a substitute for cornstarch, a good ratio is 2 teaspoons arrowroot for 1 tablespoon cornstarch.