The word “gluten” is probably so well know these days because we are all so much more aware of people with gluten intolerances and products that are gluten free. Of course, this doesn’t really describe what gluten is. Gluten is protein in wheat flour and some other cereal grains. Gluten is elastic, and when combined with water, the proteins first come together in long strings. These networks of gluten are what allow breads to rise and give just about all baked goods their shape and texture. In addition to providing a soft, chewy texture to fresh breads, gluten is also responsible for the brittle texture of stale breads; when moisture leaves a baked loaf of bread (over the course of a few days), the gluten becomes less elastic and finally will crumble under pressure, as seen in a crumbly and stale loaf.
When the protein is isolate from the starches of the flour, it is brownish-grey, tough and rubbery. This may not sound that appealing in text, but in this state it is known as seitan and is frequently used as a meat-substitute in vegetarian or vegan cooking, and the chewiness of seitan is what makes it a very convincing faux-meat.
Wheat flour, rye and barley are probably the three most common grains that sources of gluten. At stores like Whole Foods, as well as at specialty baking stores, you can buy “vital wheat gluten” on its own. Vital wheat gluten is flour-less gluten and it can be added to breads – especially breads made with low-protein whole grain flours – to increase elasticity, giving the finished loaves a much higher rise and softer texture.