Water and flour alone make a gluey mess, but with the heat of the oven, two different components of the flour exchange water molecules and in the process turn the dough into a sturdy, but spongy material we know of as bread. Starch granules and gluten molecules are both present in the wheat plant and are the two main players in the process of converting flour into bread. At room temperature, the starch in flour is contained in small, hard granules that don’t absorb very much water. Gluten at room temperature consists of long protein molecules curled up and interspersed with water molecules. But starting at around 140 degrees Fahrenheit, a change occurs.