Gluten refers to the proteins found in wheat endosperm (a type of tissue produced in seeds that’s ground to make flour). Gluten both nourishes plant embryos during germination and later affects the elasticity of dough, which in turn affects the chewiness of baked wheat products.
Gluten is actually composed of two different proteins: gliadin (a prolamin protein) and glutenin (a glutelin protein).
Though “true gluten” is sometimes defined as being specific to wheat, gluten is often said to be part of other cereal grains — including rye, barley and various crossbreeds — because these grains also contain protein composites made from prolamins and glutelins.
The Big 3: Wheat, Barley, Rye
Wheat is commonly found in breads, baked goods, soups, pasta, cereals, sauces, salad dressings & roux.
Barley is commonly found in malt, food coloring, soups, malt vinegar & beer.
Rye is commonly found in rye bread, rye beer & cereals.