I’m a whole grain enthusiast, but even I’ll admit that there are times when the bran can get in the way.
If you’re unsure what bran is there’s a particularly nice graphic here.
I notice the bran interfering the most when I’m making whole-grain pasta. Even on the finest setting on my home mill (which is quite fine!), a few sizable pieces of bran sneak through. If I try to roll whole-grain pasta too thinly, these bits of bran get caught in the rollers causing the dough to rip.
There are other reasons you might want to bolt (remove the bran from) your flour and luckily with a home mill it’s quite easy to do, especially if you’re okay with a little bit of bran making it through. Just follow these few steps!
Set your mill to a coarse grind and place a fine mesh strainer in a bowl beneath the exit chute of your mill.
Run the grain through your mill.
Gently tap the strainer against your wrist while holding it over the bowl to separate the large parts of bran from the rest of the flour.
(optional) repeat this process with the sifted flour with a finer mesh strainer to remove even smaller pieces of bran.
Run the sifted flour that collected in the bowl through the mill again, this time on the fine setting (or whatever setting you desire).
Don’t discard the bran that you’ve removed! Sometimes I will coat a shaped loaf of bread with bran before the final proof. It creates a beautiful crust. You can also make bran muffins or whatever you usually make with store-bought wheat bran.
One final note: the bran contributes a nonnegligible weight to grain, so if you need 100g of bolted flour, you’ll need to start with more than 100g of grain. You should experiment with your own set up to see how much bran you typically remove. For reference, when I bolt wheat I find that I’m removing between 20% and 30% of the total weight depending on how coarsely I grind.