Bread Flour

Bread flour — also called strong flour — is high-protein white wheat flour milled to build gluten. It is the same milled endosperm as ordinary all-purpose flour, but ground from harder, higher-protein wheat, so it carries roughly 11.5 to 13.5 percent protein against all-purpose's 9 to 11.5 percent. That extra protein is the whole point: hydrated and kneaded, the proteins glutenin and gliadin knit into more and stronger gluten, the elastic network that traps fermentation gas and lets a loaf climb high and hold its shape. Bread flour therefore gives the chewy, open crumb and tall rise of a good loaf, bagel or pizza base, where all-purpose would slump softer. On its own it is bland and faintly sweet, smelling only of dry cereal, with a soft, powdery, mealy feel — its magic is structural, not aromatic.