We get a number of questions about gluten-free baking and using gluten-free flours in recipes, so I consulted with an expert on gluten-free baking. Gretchen Brown is a registered dietitian, gluten-free blogger, and the author of Fast & Simple Gluten-Free, a cookbook featuring family-friendly recipes that take 30 minutes or less.
Can you just use a regular recipe and replace the all-purpose flour with a gluten-free flour?
Purely subbing in gluten-free flour doesn't always work. Because gluten is a structural protein, the products are often very tender and even crumbly if you just replace the flour that’s called for in the recipe with gluten-free flour. However, in some baked products such as muffins or cookies, you can make that simple substitution. When you’re making muffins or cookies, even with wheat flour, you don't want to overwork the batter or dough because overworking results in too much gluten production and a tough product. I typically use a gluten-free flour for muffins and cookies and don't add any kind of binder for extra structure.
What about baking cakes and breads?
On the other hand, cakes, breads, scones, and other baked goods with a non-gluten flour require some structural assistance from a binder. Many people use xanthan gum as a binder, and most all store-bought gluten-free products also contain xanthan gum. Though I eat it in store-bought stuff I don't bake with it. It can make things gummy and can cause tummy issues for some people.
What do you use as a binder?
I use flaxmeal slurries: 1 part golden flaxmeal to 2 parts hot water
Do you need to add a binder if you use a store-bought gluten-free flour?
It depends on the specific brand. Some already contain xanthan gum or another binder and some do not. You can look on the package ingredient list and see if any binders are listed. For example, King Arthur Gluten-Free Multi-Purpose flour is a mix of white rice and brown rice flours, tapioca starch, and potato starch, and does not contain xanthan gum.
How much gluten-free flour do I need to use?
Most store-bought gluten-free all-purpose flour mixes are about 1:1 for all-purpose flour, So, if your recipe calls for 2 cups of all-purpose flour, you can substitute 2 cups of the gluten-free flour. If the gluten-free flour you are using does not contain a binder (look on the ingredient label), then you’ll also need to add a binder if you are making anything other than muffins, pancakes, or cookies. When you start choosing other flours, like coconut flour or tapioca starch, the weights and characteristics are so different it's hard to simply replace the amount cup for cup. In those cases, you’re probably better off to follow a recipe that has been specifically developed using those types of flours.
Tip: To get the best results, it’s good to weigh your flour on a kitchen scale instead of simply measuring it out in a measuring cup. One cup of all-purpose wheat flour weighs about 140 grams. So when you substitute in your gluten-free flour, keep the cup-for-cup gram weight the same.
More from Gretchen Brown on gluten-free recipes:
Recipe for Gluten-Free Hummingbird Cake
Kumquat (gluten-free blog with recipes)
Recipe in photo: Chocolate Layer Cake