Gluten

• Gluten is the protein found in wheat and several other types of grain. Gluten is what gives bread dough its elasticity. It also makes other baked goods, such as cakes and pastries, tough and chewy.
  
  

Gluten Percentage in All-Purpose Flour

• All-purpose flour typically contains about 11 percent gluten, which is a suitable amount for baking a range of goods.
  
  

Gluten Percentage in Cake Flour

• Cake flour has a much lower protein, or gluten, content. It typically contains about 6 percent gluten.
  
  

Other Differences Between All-Purpose and Cake Flours

• Cake flour is always bleached, the process of which further breaks down the gluten. Cake flour is also ground much more fine than all-purpose, which allows it to readily absorb fats in a recipe.
  
  

Why Use Cake Flour

• Of course, you could just use all-purpose flour for everything. However, using cake flour when called for will result in a lighter, fluffier cake than one made with all-purpose flour.