What's the Difference Between Bread Flour and All Purpose Flour?
Pro tip: It's the protein
For the longest time, I didn't have bread flour in my house. Even though I'm a passionate home baker, I wasn't really into bread. I live in Chicago, where we have truly spectacular bakeries, so bread is both readily available and inexpensive. But then Pilou came to live with us. Pilou is my sourdough starter. A few years ago a dear friend gifted me a small bit of her starter, and while I was a skeptic, I took in the small bubbly blob and fed it and soon discovered that I had a sort of a pet. And there was going to be no reason to keep him if I wasn't going to make bread.
Sourdough is my favorite style of bread, so it didn't take long until I became a bit obsessed with figuring out how to use Pilou to his greatest advantage. I joined sourdough boards on social media, watched sourdough videos on YouTube and read articles and cookbooks on baking with a natural starter. I suddenly became a regular bread baker. And I started buying bread flour ten pounds at a time.
All the breads I had ever made before just used all-purpose flour. But all of the recipes I was seeing for sourdough called specifically for bread flour. Which made me wonder, what is the difference, really?
Turns out, it is all about protein. Protein in flour is one of the main components in getting gluten to develop. Which in bread, especially breads like sourdough, is awfully important for structure. Without enough gluten development, breads can't be shaped properly, and you end up with sad flat loaves like Frisbees.
All-purpose flour, on the other hand, has less protein, so it is a more versatile flour, because while you will get enough gluten development for softer breads or enriched breads, it won't have too much gluten develop for other baked goods, like cakes and cookies, which you wouldn't want to have that elastic feel in them. This is why pastry flour or cake flour is called for in especially tender baked goods, since that flour has only about half amount of protein that you find in bread flour, so almost no gluten development will occur.
So, if you are looking to bake some rustic loaves with crunchy crusts and that good elastic crumb, or if you want to experiment with some of the chewier baking like homemade bagels or soft pretzels or pizza dough, invest in some bread flour. It will make all the difference.