Barley flour is made from milling pearl barley, or whole grain barley that's had its outer husk removed. You can use barley flour as a substitute for part of the flour in a baking recipe for health purposes and to achieve certain variations in texture. However, because of its low-gluten content, you shouldn't substitute barley flour for all of the flour called for in a recipe.
Barley flour is a healthier alternative to using white and wheat flour in baked goods. According to Coleen and Bob Simmons, authors of "Cooking with Grains," barley is a low-fat, low-cholesterol grain that's high in complex carbohydrates, fiber, protein, and certain vitamins and minerals. Although barley is significantly lower in gluten than other flours, like wheat flour, people with Celiac disease or an allergy to wheat should still use caution when using barley flour as a substitute in cooking, as it is not 100 percent gluten-free.
Barley flour lacks sufficient gluten for many baked good recipes. When making baked goods that require gluten, combine barley flour and wheat flour to comprise the total flour content the recipe calls for. The more the baked good needs to rise, the less barley flour should be used, proportionately. For loaves of yeast bread, the barley flour should only constitute about 20 to 25 percent of the total flour content. For flat breads, you can use a little more. For quick breads and cookies, you can use barley flour for up to half of the flour content. It's inadvisable to use much more than 50 percent barley flour in any baking recipe.
In baking, precise measurements are essential to achieve the desired results. Freshly ground barley settles after a few days, meaning that its volume appears greater immediately after grinding than after it's been sitting a while. Therefore, to accurately measure barley flour for a recipe, don't use freshly ground barley unless it's had a few days to settle. Otherwise, you may not have enough flour in your recipe. One way to help freshly ground barley flour settle faster is to tap the container firmly against the counter.
Baked goods made with barley flour, breads in particular, have a different consistency than those made with other kinds of flour. Barley flour makes baked goods moister than flour made from other grains. Barley flour also gives baked goods a cake-like texture as opposed to a bread-like one.