Four different types of protein are found in a wheat kernel - albumins, globulins, gliadins and glutenins. Albumins and globulins are water and salt-water soluble proteins, respectively. They are biologically active proteins and are responsible for starch breakdown and other enzymatic activity. Gliadins and glutenins are storage proteins and are collectively referred to as gluten. These are the proteins we commonly associate with wheat flours.
Gluten proteins are readily soluble only in alcohol or acidic or basic solutions.
When mixed with plain water, as in bread making, they do not dissolve and form a tough, spongy dough. This dough can trap air bubbles produced by yeast or other leavening agents. Gluten proteins can vary in quality. Wheat breeders have discovered that certain types have superior bread-making capability. These superior proteins can be identified through a laboratory procedure called electrophoresis.