Q: Can you use whole wheat flour to thicken a sauce?
You can use whole wheat flour the same way you’d use white flour, but you’ll probably need to use a little more.
To thicken a sauce with white, or refined, flour, you cook the flour in fat, making a roux, so the starch relaxes and absorbs liquid. That creates the silky texture we associate with gravies and flour-based sauces. Since the bran and wheat germ are removed, white flour is higher in starch, so it thickens liquids easily.
In whole wheat flour, the bran and wheat germ remain. It’s not as high in carbohydrates as refined white flour, so it takes a little more to thicken a sauce made with the same amount of liquid. Where you might use 2 or 3 tablespoons of white flour for 2 cups of liquid, you might need to use 4 or 5 tablespoons of whole wheat flour. The sauce made with whole wheat flour also might be a little darker with a nuttier flavor.
The bran and germ also make whole wheat flour get rancid faster. If you want to use it regularly, make sure you keep it in the freezer so it doesn’t get an off taste.