Gluten
The stretchy protein network that forms when wheat flour is mixed with water and worked.
Gluten forms when two groups of wheat proteins, glutenins and gliadins, meet water and are kneaded. The result is an elastic web that traps gas, which lets bread rise and gives noodles their chew. Barley and rye contain related proteins. People with coeliac disease must avoid all of them, because they damage the gut. Rice, maize, millet and buckwheat have no gluten. Washed free of starch, gluten becomes seitan, a meat substitute.