There are several types of gluten flour, most derived from wheat. Gluten is a protein found abundantly in the endosperm of wheat that adds stickiness and sponginess to dough. When people cook with other whole grains, they may not have adequate gluten, and might need to use a bit of pure gluten in order to make breads and other baked goods lighter. There are a few ways to add extra gluten to dough, most of them employing some type of gluten flour to accomplish this.
Pure gluten flour or vital wheat gluten is flour that is treated so that wheat bran and starch are removed. This means it’s much lower in carbohydrates, and much higher in protein. A quarter cup (30g) of this flour can contain 23 grams of protein, though it’s seldom the case that you’ll use very much in a recipe. Gluten flour in small amounts is added to other whole grain flours, with some recipes calling for about a cup of it at most for a loaf of bread. It has become popular in low-carb foods because the removal of starch means only about 6 grams of carbohydrates remain in a quarter of a cup.
Another type of gluten flour is regular white or wheat flour with additional gluten added. This may be called high gluten or bread machine flour. The amounts of the wheat protein differ from brand to brand, but usually this type of flour contains about 12% protein. You can contrast this to the pure form, which is about 75% pure protein.
Many love using bread machine flour because it tends to result in much lighter and fluffier bread. Yet it’s not best if you’re trying to keep carbohydrates low. Though carbohydrate content is lower than in standard white flour, high gluten flour still holds about 54 grams of carbs per cup, as opposed to 24 grams of carbs per cup of pure gluten.
You’ll probably be able to find bread machine flour in most grocery stores. You may have to look a little harder to find pure or vital wheat gluten. Your local health food or natural foods store is usually the best bet, and you’ll probably even be able to find this in bulk form. You should note some people have sensitivity to wheat gluten, either in severe forms as with Celiac disease, or in mild forms. If people in your home seem not to tolerate wheat gluten well, you may need to stick to other less glutinous multi-grain flours.