Gluten

A tough, elastic, brown, water-insoluble, non-starchy protein substance remaining when the flour of wheat, corn, rice, or other cereal grain is washed to remove starch. Gluten is composed of a mixture of 18 plant proteins. It is hygroscopic and will form an elastic dough when mixed with water. Gluten must be removed to make starch paste. Dilute aqueous mixtures of gluten have been used as adhesives. Prior to the 19th century, the term was used to refer to any of several adhesive materials.