How to Substitute Cornstarch for Flour in Recipes

Cornstarch works well in sauces, gravy, pie fillings, and fried coatings

How to substitute cornstarch for flour in recipes. FotografiaBasica/Getty Images

Lots of recipes use flour as a thickener, a coating or another ingredient. If you're on the gluten-free diet because you have celiac disease or non-celiac gluten sensitivity, you obviously can't use wheat flour for this purpose, so you'll need to substitute cornstarch.

The good news is, it's pretty easy to substitute cornstarch for flour when your recipe calls for a thickener (as in a gravy, a sauce or a pie) or a coating for fried foods.

You can't use cornstarch as a substitute for flour in baked goods, but that's where cup-for-cup gluten-free flour blends shine. 

Here's a guide to substituting cornstarch for flour in recipes.

Thickening Gravy, Sauces or Pie Fillings with Cornstarch

Cornstarch works remarkably well as a thickener in sauces, gravy and pie fillings—in fact, I think it works even better than flour. Be aware that these foods will be more translucent (this occurs because cornstarch is pure starch, while flour contains some protein), and you won't be able to taste the cornstarch the way you sometimes can taste the flour.

But you can't use cornstarch as a tablespoon-for-tablespoon substitute for flour. Generally speaking, you should use 1 tablespoon of cornstarch for each cup of sauce/gravy of medium thickness. 

The most important things to remember when using cornstarch as a thickener in recipes:

  • Use half as much cornstarch as you would flour. For example, if the recipe calls for 2 tablespoons of flour, use 1 tablespoon of cornstarch. If the recipe calls for 1/4 cup of flour, use 1/8 cup of corn starch. (The same is true for other starches, such as arrowroot starch, potato starch, and tapioca.)
  • Don't add the cornstarch directly—it will clump up and form lumps in your sauce that will be very difficult to dissolve. To avoid this problem, first mix the cornstarch in a little cold water (1 tablespoon water to 1 tablespoon cornstarch) until it's dissolved, and then pour the water/starch mixture (known as a "slurry") into what you're cooking. Make sure the water you use is cold, and keep stirring as the mixture begins to thicken.
  • Cook over medium-low to medium heat, because high heat can cause lumping.
  • You might want to avoid freezing any sauces or gravy you make with cornstarch since they won't freeze well (they actually turn spongy).

Frying with Cornstarch Instead of Flour

You easily can use cornstarch instead of flour as a coating for fried chicken, fried fish or other fried dishes. Cornstarch actually will create a crisper coating that will hold up to sauces better and will absorb less of the frying oil (leading to a lower-fat meal).

Here are some tips for frying with cornstarch:

  • Make sure you have a light, even coating of cornstarch on the food you're frying. Heavier coatings can get gummy.
  • Consider a 50-50 blend of cornstarch and gluten-free flour—this will give you a coating that's closer to wheat flour-breaded fried chicken.

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