Flour proteins are surrounded by water (hydrated) during the mixing of doughs and batters, thereby forming gluten strands. Gases that are formed during leavening are trapped by the thousands of small, balloonlike pockets that gluten forms. These gluten strands are highly elastic and allow the mixture to stretch as the trapped gases expand. When too much gluten develops, the mixture becomes tough. Sugar performs the extremely important role of tenderizing agent during the mixing process by attracting liquid, which in turn slows gluten development.