Cornstarch Vs. Flour: Which Is Better For Thickening Food?
There will come a day when you will probably need to thicken up a sauce. It might be a gravy for the Thanksgiving turkey or a rich sauce for an etouffee. Needless to say, you'll be looking in the pantry and asking the age-old question: cornstarch or flour? Cornstarch and flour are both great thickening agents, but they are also very different. A lot depends on the cuisine you are cooking and the time you have.
According to MyRecipes, making a flour roux takes more time than a cornstarch slurry. You'll also mix a roux first, whereas a cornstarch slurry is added into a recipe as a final step. Time and fat type will determine your roux, too. A quick roux made by cooking equal parts flour and butter together will create a blond roux, while slow cooking lard, oil or beef fat with equal parts flour for a longer period of time will create a brown roux that you could use in something like a Cajun gumbo. Roux are best if you're cooking something slow and you want the dish to have a rich, creamy gravy or sauce with it, such as with Thanksgiving gravy.
When to use cornstarch instead of flour for thickening sauces
Sometimes, you don't have the time for cooking a flour roux. Other times, you've already started cooking and then realize you need to thicken up a sauce. This is when cornstarch is your friend. Simply combine one tablespoon of cornstarch with one tablespoon of cold water in a bowl, making sure to whisk out any possible lumps. Then, add it to your cooking sauce in the final few minutes of cooking and you're left with a perfectly thickened sauce. Because cornstarch typically gets combined with water instead of fat, there's no flavor to it, making it work with a wide range of dishes, according to MyRecipes.
You'll find that you use less cornstarch than flour, too, since cornstarch is literally all starch, while flour is only partially starch. Why does this matter? Because starch is the ingredient in both that's responsible for thickening and expanding. What if you don't have corn starch or flour but still want to thicken up that sauce? Try arrowroot, potato starch, tapioca starch, or rice flour as substitutes.