Unbleached Flour Has More Protein

• Unbleached all-purpose flour is off-white flour that hasn't been chemically whitened, although it may still contain maturing agents and chemicals to improve dough. All-purpose flour has a protein content ranging between 8 and 11 percent. More protein means the flour has more capacity to make gluten when mixed with water. Gluten forms the sticky strands in the dough that capture the carbon dioxide bubbles caused by leavening. The leavening process makes baked goods rise up as the air bubbles expand when heated during baking, causing the dough to lift and then set. Unbleached all-purpose flour works well for achieving good rise in yeast bread, strudel, Danish pastries and other sturdy baked goods because of its ability to create a strong structure.

Chemicals Whiten Bleached Flour

• Bleached flour undergoes an oxidation treatment that causes flour's yellow pigment to turn bright white. Chemicals permitted for bleaching flour include potassium bromate, benzoyl peroxide, chlorine dioxide and chlorine gas. The bleaching process breaks down some of the protein in the flour, thereby decreasing its capacity to make gluten. This lower gluten capacity in bleached all-purpose flour gives baked goods a finer grain and softer texture. Baked goods that don't require lots of rise, such as cookies, quick breads, pie crusts, pancakes and waffles, benefit from using bleached flour.

Downsides to Bleached Flour

• The downside to using bleached flour is the chemicals themselves. Some particularly sensitive people may complain they notice a bitter aftertaste to baked goods made with treated flour. Those concerned about chemicals in their food also resist using bleached flour, even though unbleached flour may also contain some chemicals. By law, all flour is required to list any chemical additives on its label, whether unbleached or bleached.

Flours for Bread or Cakes

• Nutritionally, unbleached or bleached all-purpose flour are virtually the same. They can be substituted for one another on a one-to-one basis in any recipe that calls for all-purpose flour. Two other types of flour that can be found in unbleached and bleached versions are bread flour and cake flour. Yeast breads may rise higher with unbleached bread flour, which has a protein content of 12 to 14 percent and therefore high capacity for gluten structure. Baked goods with lots of sugar, which tends to inhibit leavening, may rise better using bleached cake flour, a low-protein, fine-grain flour that offsets sugar's inhibition, therefore lifting better.