Can You Make A Roux With Cornstarch? | With 5 Alternatives

Roux can be used in many cooking applications as a thickening agent. From sauces and soups to casseroles, stews, and curries, roux is considered an indispensable ingredient. Making a roux is relatively easy and is accomplished by correctly combining equal parts of flour and fat. But what do you do when you set about making your roux and realize that you don’t have flour on hand?

It is possible to make a roux using cornstarch. However, the process and characteristics of the roux will be a little different from a flour-based roux. Four other flour alternatives include sweet rice flour, arrowroot, oat flour, potato flour, or all-purpose gluten-free flour.

People may look for alternatives for flour in a roux recipe for a number of reasons. They may not have flour on hand or have a gluten intolerance. 

Can You Make A Roux With Cornstarch?


For many purists, roux is made with equal quantities of a fat such as butter or vegetable oil with an equal amount by weight of flour. In their opinion, this is how a roux is made, and there is no other way. That is because flour offers flexibility that many substitutes cannot match.

Even so, there are several legitimate alternatives to flour in making a roux, and cornstarch is one of them. However, the preparation process will be somewhat different.

When making a flour roux, the mixture is cooked for varying amounts of time, depending on whether a white roux, blond roux or brown, or dark roux is required. Flour is actually required to change the color and enhance its flavor. As it is cooked, the taste profile is altered substantially. The longer it cooks, the nuttier the flavor of the roux.

You do not get this effect with cornstarch. However, using cornstarch is not without its advantages.

Advantages Of Using Cornstarch In A Roux

Making a roux with cornstarch has some advantages over a roux made with flour.

  • It is quicker to make- You do not need to take a lot of time to cook a cornstarch roux; it can be made in somewhat more quickly.
  • It makes a clear, shiny roux- Sometimes, you don’t want the roux to change the sauce’s color. A cornstarch roux is suitable for this purpose.
  • Subtle dish flavors shine through- Dishes with delicate flavors can become overwhelmed by a flour roux, but a cornstarch roux will allow delicate dish flavors to remain.
  • You need less roux- Cornstarch is a more effective thickener than flour, so you would need less roux for your dish.

Disadvantages Of A Cornstarch Roux

  • It does not keep in the refrigerator- You will not be able to store a cornstarch roux for later use, so only make the amount you need for the dish at hand.
  • It does not brown- Unlike a roux made with flour, a cornstarch roux will not darken with a longer cooking time. In fact, cooking it for a long time will reduce its thickening capability.
  • It does not have as much flavor- You will need to add flavor components such as black pepper or other herbs and spices to enhance the flavor of cornstarch roux.

Cornstarch is a much more effective thickening agent than wheat flour, but it also does not have as much flavor as a roux made with flour. This may require adding herbs and spices to a cornstarch roux to make it more flavorful.

Related Can You Make a Roux with Margarine? | A Culinary Exploration.

How To Make A Corn Starch Roux

The method of making a roux with cornstarch is different than the standard method used with flour. The quantities are different, as are some of the ingredients.

What you will need for this recipe:

  • 2 tablespoons of fat- The fat can be butter, drippings from the meat you have cooked, bacon fat, vegetable oil, or even margarine.
  • 1 tablespoon of cornstarch
  • 1 cup of liquid- This liquid can be milk, water, or stock, depending on what you want to use the roux for. Milk is used for cheese sauce or white sauce, whereas water or stock is better for gravies, stews, or soups.

Cornstarch roux process:

  • Step 1: Heat the fat in a saucepan over gentle heat, taking care not to burn it or brown it too much.
  • Step 2: Add ¾ of the liquid to the fat in the pan, stirring the mixture as you add the liquid.
  • Step 3: Place the other ¼ cup of liquid in a cup. Put the tablespoon of cornstarch into the cup and mix it thoroughly into a smooth paste. This will prevent lumps of cornstarch from developing in the roux.
  • Step 4: Spoon the cornstarch paste slowly into the pan little by little, stirring vigorously while you add it. This will prevent any lumps from forming as it thickens.
  • Step 5: Stir the roux for a few minutes on low heat until it reaches the desired thickness. Then remove it from the heat.
  • Step 6: This step is optional. You can add additional seasonings such as black pepper, a teaspoon or two of onion powder, or a sprinkling of chili flakes to enhance the flavor.

Voila! You can now add this roux to your stew, gumbo (please see the video below), soup, cheese sauce, white sauce, or gravy and it will add flavor as well as thicken your dish.

Pro Tip: If the roux is too thick, you can add a little more liquid to thin it out, stirring while you add it.

Here is a video I did showing the process of using cornstarch instead of flour to make a roux. I even do an experiment to show what would happen if you just pretended it was flour.

Using Cornstarch As A Thickener Rather Than A Roux

Sometimes, you may just need a thickener and do not want to go to the trouble of making a roux. Cornstarch is excellent for this application!

  1. Place two teaspoons of cornstarch in a cup and mix with a little cold water to create a viscous liquid, similar in consistency to honey. Do not use hot water to incorporate into the cornstarch; it will go lumpy!
  2. Pour half of this mixture into your stew, gravy, or soup, stirring while you do so. Continue to stir the dish for a few minutes to see if it achieves the desired thickness. If you still need more thickening, add the rest of the mixture and continue to stir the dish for a few minutes.

Important: If necessary, you can add more cornstarch if you need to. Just be careful and add slowly; you cannot remove it once you have added too much. It is best to add the cornstarch little by little since if you add too much, your dish will become gelatinous.

5 More Roux Flour Substitutes

Cornstarch is not the only substitute that can be made for flour in a roux, and the others mentioned here are, in some cases, a better alternative for a roux than cornstarch.

  1. All-purpose gluten-free flour- This is probably your best choice as a flour alternative in a roux, especially if you have an intolerance for gluten or suffer from celiac disease.
  2. Sweet rice flour- This rice flour makes an excellent substitute for flour in a roux made in the standard method.
  3. Oat flour- Oat flour can be substituted for flour in making a roux in the traditional flour-based process.
  4. Potato flour or potato starch- Potato starch has very similar characteristics to cornstarch and also makes a great thickening agent. To use potato starch as a substitute, use the same recipe as you would for cornstarch.
  5. Arrowroot- Arrowroot can be used in the cornstarch roux recipe as a cornstarch substitute. However, do not use arrowroot with dairy products such as milk or cheese. Arrowroot tends to take on a slimy consistency when used with dairy products.

Final Bite

In my experience, cooking is a very individual activity, and we all have our own experiences in what works and what doesn’t. You will find that some people are adamant that you cannot make a roux with cornstarch, and others that say it can be done. I am one of the latter folks.

I believe you can make a roux with a number of ingredients other than flour; my five alternatives are an example of this. Much of cooking is experimentation and personal experience, so if you have never make a roux with cornstarch, why not give it a try and tweak our recipe till you find ratios that work for you!

I hope this article has given you some ideas as to alternatives in the kitchen should you run out of your normal ingredients or have a guest around that cannot tolerate wheat-based ingredients.

Thanks for stoppin’ by!

Jelly Grandma

For more, don’t miss 8 Ways to Thicken Gravy Like A Pro.

Anne James

Anne James has a wealth of experience in a wide array of interests and is an expert in quilting, cooking, gardening, camping, mixing drinks (bartending), and making jelly. Anne has a professional canning business, has been featured in the local newspaper as well as on the Hershey website, and has been her family canner for decades. Anyone growing up in the South knows that there is always a person in the family who has knowledge of the “old ways,” and this is exactly what Anne is. With over 55 years of experience in these endeavors, she brings a level of hands-on knowledge that is hard to surpass. Amazingly, she doesn’t need to reference many resources due to her vast wealth of experience. She IS the source. Anne wants nothing more than to pass on her extensive knowledge to the next generations, whether that be family or anyone visiting her website, her YouTube channel, or

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