What is gluten?

Gluten is a grayish, elastic, sticky substance found abundantly in the white of an egg, in grains, and in lean meat, etc. As a food it builds muscle. There are about eight pounds of gluten in one hundred pounds of wheat flour. It is the elastic gluten of wheat dough that enables the gas formed by yeast to make bubbles and leaven the dough. The gummy substance obtained by chewing a mouthful of wheat is nearly all gluten. The gluten of sound wheat gives flour and bread a slightly yellowish tinge, but it is not accountable for dark bread. Quite a controversy has arisen as to whether it is legitimate to whiten flour by "bleaching."