The worst thing when making a recipe is when you stumble upon an ingredient that you don't have. Maybe you just skimmed over it before and read "flour," but it actually says bread flour, and all you have is all-purpose flour. So what really is the difference between all purpose vs bread flour? Why is your recipe calling for bread flour instead of all-purpose flour? Well, you're about to find out.
Where does flour come from?
Baking flour comes from the wheat berry of the wheat plant, which consists of three parts: the bran, endosperm, and germ. The bran is the hard outer shell. Once this is broken, it adds small pieces of bran to the milled flour. These small pieces are fiber.
The endosperm is the inside of the wheat berry and makes up most of the mass of the wheat berry. Only the endosperm is used to mill white flours.
The germ is the very inside of the wheat berry. This is used when milling whole wheat flour.
What is all-purpose flour?
All-purpose flour says it right in the name, it's best to use in all sorts of everyday foods. The protein content of all-purpose flour averages at about 11%, so it is a median amount of protein compared to bread and cake flour. This means that it works well with breads and cakes.
What is bread flour?
Bread flour is specialized for using in yeasted breads. It has a protein content of around 14%, which is much higher than that of all-purpose flour. This larger amount of protein helps develop more gluten in the bread to create a higher rise.
Protein content determines how much gluten can be formed by that particular flour. The more protein in the flour, the more gluten can be formed, and the denser and chewier the texture will be. This is why you use a high-protein flour for chewy breads and a low-protein flour for light, airy cakes.
Can you substitute one for the other?
In a pinch, it's okay to substitute one for the other in a one-to-one proportion. However, for the best results, you should use the flour called for in the recipe. As learned above, they call for that flour for a reason.
So in sum, what really is the difference between all purpose vs bread flour? Bread flour has a higher protein content, so it makes denser, chewier bakes like bread. All-purpose flour has a median amount of protein and is good for making most all baked goods.