Many people use all purpose flour in bread making instead of bread flour. I started wondering what the difference is. It turns out that the difference is gluten.
Gluten is a type of protein found in flour. More gluten in the flour makes the bread slightly heavier, but more importantly it makes it stronger. That means that as the yeast ferments the bread will hold the carbon dioxide and rise. If it’s not strong then the carbon dioxide will escape and the bread won’t rise as high.
Bread flour has more gluten than all purpose flour. However the amount of gluten in particular brands of flour varies. In general, all purpose flour has a gluten content of 9% to 12%. Bread flour typically has a gluten range of 10% to 13%. Note the overlapping areas.
If you’re using all purpose flour in your bread machine and it works for you, that’s great. It may be that your brand of flour is in the upper, and perhaps overlapping, range of the gluten levels.
Here’s more information on flour: