What is "spent grain"? Where do I get it, why should I use it, and HOW do I use it?
Brewers soak grain in hot water for a fairly long time to extract the malt sugars from the grains into the water. Then they strain off the malty sugary water, boil it with hops, and use yeast to turn the boiled malty, hoppy, sugary water into beer.
The left over grains are called "spent grains" because the malty sugars have been removed from them. While from the brewe's point of view the goodness in the grain has been spent, they still have lots of fiber, flavor, and protein. Many breweries sell their spent grains to hog farms.
The flavor is the key here - these grains can add a real flavor boost to your breads or crackers.
Because the grains were soaked in water, they are wet (*doh*). And that means that they will grow undesirable organisms very quickly. So, if you want to use spent grains, call your local brewery and ask if you can have some grain. If they say yes, ask when they brew and go there on the brewing day. Bring along some clean waterproof containers to transport the grain. You should treat the grains as you would any perishable food - keep it above 140F or below 40F, keep it protected from insects and other pests.
Once back at your home or bakery, put about a pound of grain on a half-size sheet pan, spread it around and put it in a 250F oven. Stir it up every 15 minutes or so until the grain is very dry. Once dry, you may cool it and use it, or freeze it in your favorite freezer containers. Some papers we've seen suggest an upper limit of about 10% spent grain, as a baker's percentage. Our experiments bear this out - beyond 10% the grains start becoming annoying. If you want less crunch, you can mill the dehydrated spent grain into a flour.
Should you use ground spent grains or coarse ones? It's really a matter of taste. I like crunchy coarse breads, so I like to use the spent grains just dried. If you prefer a more homogeneous bread, or cracker, go ahead and grind them - in a flour mill, a blender, a food processor, or even a mortar and pestle.