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Cornstarch is made by grinding the endosperm part of the corn kernel into a white powder that is very starchy. This starch plays a key role in cornstarch being used as a thickening agent. Used as a thickener in soups, curries, desserts and even ice cream, cornstarch can also be used to easily substitute for agar flakes, another gelling agent that's relatively underrated.

What Is Agar Agar?

Agar agar is a thickening agent that’s derived from seaweed and used as a vegetarian-friendly alternative to gelatin. Made from a mixture of carbohydrates that are extracted from Red Sea algae, agar is used to thicken everything from soups and Jell-O to jams and ice cream.

Agar agar gelatin is free from animal products, which is why agar flakes are commonly used in vegetarian and vegan cooking. Best of all, agar flakes have no flavor and so do not affect the overall taste of the desserts or savory recipes they are used in. Agar agar gelatin is an alternative to traditional gelatin. They are very similar, except that recipes using agar tend to be firmer in texture than those using regular gelatin and are able to withstand heat rather well.

Agar agar is sold either as bars, in powder form or as agar agar flakes. Agar powder is very easy to work with and dissolves almost instantly. Flakes need to be blended to achieve a smooth, gelatin-like consistency. Bars are best if you need to buy agar agar in bulk; they can be turned into either agar flakes or powder by blending in an electric high-speed blender.

Substituting Agar Flakes With Cornstarch

If a recipe calls for the use of agar flakes, but you don’t have them available or can’t find them in the grocery store, you can always use cornstarch as an agar powder substitute. Substituting agar flakes with cornstarch is easy; all you have to do is use a simple 2:1 ratio of cornstarch to agar flakes. So, 1 tablespoon of agar flakes will use 2 tablespoons of cornstarch, the agar agar alternative.

If you're using agar powder, which is finer than agar flakes, it's fine to use a 1:1 ratio of cornstarch to agar flakes. So, 1 tablespoon of agar powder will use 1 tablespoon of cornstarch. When diluting with cold water to create a slurry – this should always be done before adding cornstarch to any heated liquid to prevent clumping – use a 1:2 ratio of cornstarch to water. So, for 1/2 tablespoon of cornstarch, dilute it with 1 tablespoon of water.

What Can You Use Instead of Agar Agar?

Well, for one, cornstarch. But if that’s not available, or if you suffer from a corn allergy, arrowroot powder (sometimes called flour or starch) is also a good thickener, especially in soups and liquids. It is the perfect agar agar alternative. This gluten-free flour is extracted from the root of the leafy, tropical plant, arrowroot, which is commonly grown in tropical countries around the Caribbean and also throughout India.

Another reason arrowroot is a great agar powder substitute is because it leaves no lingering aftertaste in thickened recipes and it also holds its consistency and texture when frozen, unlike cornstarch.

Like cornstarch, tapioca starch, which is also known as tapioca flour, is used as a thickening agent and an agar agar alternative. Tapioca flour is a starch that’s extracted from the cassava root, and like other thickening agents is gluten free and great for thickening soups, sauces and fillings. Tapioca flour is commonly used in baking.

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About the Author

Christabel Lobo

Christabel Lobo is a freelance writer focusing on all-things food, travel, and wellness. Her writing has appeared in Tenderly, SilverKris, Byrdie, Trivago, Open Skies, Fodor’s, London’s Evening Standard, Silkwinds, HuffPost, Barclays Travel, Pint Size Gourmets, and on her personal yoga & travel blog, Where’s Bel. Feel free to check out her design and writing portfolio: christabel.co