How to Thicken Soups

(a reader asks...)

How do I thicken soups when I can't use flour. I'm allergic to wheat so can't use the flour and water mix that so many recipes call for. I've looked at the ingredients on the commercial gravy mixes, but they have wheat, too. Any ideas on how I can get nice, thick soups without flour?

Coleen, the Soup, Stew, and Chowder Recipes editor replies:

Alternative Ways to Thicken Soup

One way is to mix cornstarch and cold water, then add it to the soup as you would the flour and water mix. It takes less cornstarch than flour to do the same amount of thickening. Use half as much cornstarch as you would flour.

Soups thickened with cornstarch can look just right and then seemingly all of a sudden look thin again. There are a few things that could cause that -- too much stirring, cooking for too long, having too much fat in the recipe, and not having enough liquid. Yes, that last ones sound contradictory, but cornstarch needs liquid to cause the particles to swell, and if there isn't enough liquid, it won't thicken correctly -- though with most soups this shouldn't be a problem. Enzymes will thin cornstarch thickened soups, also, so if you taste the soup and then put that spoon back in the soup, it will thin down quickly.

Another quick and easy way to thicken soup is to add instant mashed potato flakes. This works especially well for chowders where you want an opaque, white base.

Pureed vegetables another option. What kind depends on the type of soup you are making. Keep in mind that they will add color. That is often a good thing, but something you need to be aware of.

I've used cornmeal and mesa to thicken chili and stews. It works well for those that simmer for a longer time.

I've also unintentionally thickened soup with cooked rice. I added the cooked rice to soup that was to simmer for a couple of hours. Between the extensive cooking time and my stirring it, the rice broke up. Instead of having identifiable grains of rice, I had a thick soup.

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