Gluten refers to the proteins found in cereal grain’s endosperm (a type of tissue produced in seeds that are ground to make flour). Gluten both nourishes plant embryos during germination. Gluten is actually composed of two different proteins: gliadin (a prolamin protein) and glutenin (a glutelin protein). Though “true gluten” is sometimes defined as being specific to wheat, gluten is also found in barley and rye. Gluten is also found in hybrids of wheat such as spelt, kamut, and triticale.
When flour is mixed with water, the gluten proteins form a sticky network that has a glue-like consistency. This glue-like property makes the dough elastic, and gives bread the ability to rise when baked. It also provides a chewy, satisfying texture. The elasticity of gluten also allows dough to trap air bubbles when rising making baked bread light and fluffy.
Interestingly, the name glu-ten is derived from this glue-like property of wet dough.