Sentence:  Chew on a small piece of dough, and it becomes more compact but persists as a gum-like, elastic mass, the residue that the Chinese named “the muscle of flour” and that we call <WSD>gluten</WSD>. It consists mainly of protein, and includes what may well be the largest protein molecules to be found in the natural world. 
Meaning of the word marked with <WSD> tags:  The major protein in cereal grains, especially wheat; responsible for the elasticity in dough and the structure in baked bread. (from 19th c.)