Baking homemade bread isn't exactly rocket science, but there's still a lot going on inside even the simplest loaf. The yeast itself is a living organism, which makes it pretty unpredictable, and other ingredients like sugar and fat can totally change the way the dough behaves. One of the most important ingredients is flour, and the kind you choose makes a big difference. Most recipes work fine with all purpose flour, but some make a point of demanding bread flour instead. If that's not something you keep on hand, you can fake it by converting your all purpose flour.
What's the Difference Between Flours?
There are all kinds of flours on your supermarket shelf, and what sets most apart is their level of protein. There are two specific proteins in wheat called glutenin and gliadin, and when you put them together and add water, they form gluten. Gluten is long, elastic strands of protein that give your dough its ability to stretch, but it's a mixed blessing.
In breads and other things made from yeast doughs, you want lots of gluten. It traps the bubbles of carbon dioxide the yeast produces, making the equivalent of millions of little balloons inside your dough. When they blow up, your bread rises up light and perfect. In biscuits, pies and cake dough, you want to avoid gluten. The same stretchiness that works to your advantage in bread is your enemy here, because it makes your baked goods tough and chewy. That's why cake and pastry flour have low levels of gluten, and bread flour has lots of it. All purpose flour, the one you probably keep in your pantry, is a compromise that falls somewhere in the middle. You can use it for any kind of baking, but it has limitations.
All Purpose Flour Is Variable
The thing about all purpose flour is that it's variable. It's made by blending so-called hard wheats, which have lots of gluten, with soft wheats, which don't. Each milling company has its own blend, and there are regional differences, as well. If you grew up in the Northeast or the Midwest where hard wheat is common and people bake a lot of bread, your all purpose flour probably has 10 to 12 percent protein. If you're from the South, where soft wheat is the staple and biscuits are king, your all purpose flour might have only 9 percent protein. That's a big change, and it can mean the difference between a pretty good loaf and one that's dense and disappointing. That's one reason why recipes often specify bread flour, with its consistently high protein level.
Upping the Gluten Content Manually
If you don't want to commit to keeping both bread flour and all purpose flour in your pantry, but still want to enjoy the light, high loaves you'd get with bread flour, there's an easy answer. Just keep on hand a small bag of concentrated gluten flour, also known as vital wheat gluten. You can sometimes find it in the specialty section of your supermarket, or you can order it online if need be. It's very high in gluten, about 75 or 80 percent, so adding just a little will crank up the protein content in your all purpose flour. If you live in an area where the all purpose flour is already relatively high in protein, adding a teaspoon of gluten per cup of flour will do the job. If you're in the South, make it a tablespoon per cup.
Using the Gluten for Other Things
You can also use gluten to make a lighter loaf with whole wheat or rye flour, which tend to not rise as well as white flour. A tablespoon per cup is about right for those, too. You can even use gluten with non-wheat flours. That's handy if you're low-carbing, or baking things for someone who is. If you add vital wheat gluten to the low-carb flour mixture, you end up with something that behaves pretty much like regular flour. If you buy a big bag, you can even use the gluten flour to make vegetarian seitan, or "wheat meat."