Gluten

Gluten is what gives bread dough its elasticity, structure, and oven-spring. Gluten is created when the two proteins in the flour—glutenin and gliadin—are combined with water. As the mixture is blended (kneaded), the two proteins bind with the water, and with each other, forming thin, stretchy sheets of gluten. These elastic sheets trap and hold the gases produced by yeast, making gluten essential for yeast-leavened breads but disastrous for quick breads and cakes, where a dough or batter without elasticity is desired. Hard flours have more protein and therefore produce more gluten; soft flours have less protein and produce less gluten.