In order to turn your spent grain into a suitable flour with which to make bread, you'll need a few things:
- Spent grains, of course
- Cooking trays
- Oven with low heat settings
- Grain mill (or food processor)
- Mason jar (or other storage container)
Step 1: Dry the Grain
Since you just made beer, your spent grain will be wet, so the first step is to dry your grain. Spread the grain on your cooking tray about half an inch thick.
Turn your oven on to the lowest heat setting available. My oven goes down to 170 ºF, but lower works as well. You want to dry the grain without burning it. Make sure to leave your oven door cracked open to let the moisture out.
This drying process should only take a couple of hours. Stir the grain periodically and check how damp it is. When the grain is dry, it will be lighter weight, and crumble in your fingers.
Step 2: Mill the Grain
Now that your grain is dry, it's time to mill it. If you are using a mill, adjust to the coarseness you want. If you are using a food processor, you'll have to keep an eye on it and stop when it's at the desired coarseness. Some people (or bread recipes) prefer coarser grain for texture, but you can also grind it very fine and use it in place of your whole grain flour.
Using a mill is arguably more fun, but most certainly a lot more work! I ended up milling my grain twice to get it fine enough to use a flour, so I ended up doing twice as much work as I should have.
Step 3: Store and Use the Grain
Congratulations, you made flour from spent grain! Now store it in an airtight container and use it next time you bake bread. Some people also store their flour in the freezer so it lasts longer.
Happy spent grain bread making!