Acorn flour is one of the most nutritious (and delicious) of forgeable foods out there––high protein, high mineral content. It is admittedly a fair amount of work, depending on your help and your equipment, but think of it this way: you didn’t have to weed, cultivate or plant anything to get them. You are literally just harvesting and processing. So in terms of work, it is probably equally time intensive, or perhaps less time intensive, than your average cultivated grain.
Acorns are the seeds of oak trees. They can be found in parks, rest areas, cities and farms––by the boatload in masting years. Depending on region and tree species, acorns come in many different shapes and sizes. For us, we have several large white oak trees around that often give fat, healthy acorns. They start to drop sometime in the October, though I recommend waiting until after the first frost to harvest, because the first acorns that drop are often the less viable nuts. To make it easy, harvest acorns without holes in the side. The holes are from a tiny grub that eats, and ruins, the acorn. Once you have harvested all you would like, do a float test to check the rest of your acorns by pouring water over the group, and removing the floating nuts. Then stir and repeat. You will still find bad ones, but markedly less than without the float test.
Spread the acorns out on a baking sheet (or ten), then place them somewhere warm and well-ventilated to dry. We dry our either above our stove or in the greenhouse. Leave them for at least two to four weeks depending on heat and air flow.
I hesitate to recommend our first shelling method, but you can find what works for you. Or maybe you have a method you’d like to recommend. Some people run it over with their cars, but without cement that wouldn’t work for us as our driveway is dirt (or mud). Before we got a nutcracker through the KSU small farmers’ grant, we cracked each acorn individually with a garlic press. This goes surprisingly quick, though it’s a lot of work when dealing with five gallons of nuts. After we have cracked them all, we go back through and remove the nut. I enjoy this part of the process as it’s another chance to remove bad nuts. It will take a couple days per bucket of acorns this way, but, you know, it’s winter so what else do we have going on?
Leaching is the process by which you use water to remove a mineral, nutrient or chemical. In the acorn’s case, it’s tannins you want to remove. Acorns are practically inedible before leaching, like eating underripe persimmons (voice of experience here). And there are many different ways to do it. I’ll give you the two we know. First, there is the creek method––the lazy method. Stuff all the nuts into a permeable sack (pillow cases work), tie it to a tree in a clean creek or spring and let it sit there submerged for a month, checking on it regularly for holes. There is also cold-leaching which is essentially letting the nuts (or ground flour, which we do after leaching, but some do before) soak in cold water that is changed every few days, or percolated if you’re fancy. Taste the nuts periodically to test for tannins––when you can tolerate it, you’re good to go. As for hot leaching, I hear it’s fast, but like most fast things in food, sacrifices flavor and texture so we don’t bother. You can also neutralize the tannins with lime or lye, but we don’t have any experience with that. If you do, please feel free to share!
WASHING THEN DRYING AGAIN
After leaching we remove the acorns and, if done in a creek, wash them. While washing them we try to remove as much skin as possible, as the skin tends to maintain some of the tannin. Don’t go nuts here––pun not necessarily intended. As far as I can tell, a little skin doesn’t seem to make a big difference, plus it adds a little darkness to the color. You do still want to wash off any silt or dirt that has collected on your acorns, though, if you used the creek method. Dirt definitely makes a flavor, and textural, difference. Next, spread them out and, for creek leaching, dry them again for a week or so. This will help kill any bacteria, and also, make them easier to grind.
GRINDING INTO FLOUR
People may use the leached acorns whole but typically they are ground for flour. Which means the job’s not done yet. We didn’t have a nice grinder when we first started doing acorns, but we are proof you don’t need one. We had a meat grinder, which we ran them through first to break up the large chunks, then we finished the nuts in a coffee grinder. Et voila! Acorn flour!
COOKING WITH ACORN FLOUR
Acorn flour is not wheat flour. You can use it for grits, for certain pie crusts, and mixed in with cookies or pancakes (our personal favorite) but it will not rise like wheat. Be creative. Try thickening a soup with it. Try the “grits”. It doesn’t make a great gravy (it separated when we tried it), but it does make a good thickener for sauces, or a nice addition to fry batter. You can use it all at once or think of it as a flavoring––go nuts! (Pun kind of intended that time.)
Ratio: One gallon of nuts makes roughly one quart of flour
Harvest time: Around ten minutes per gallon
Active time: Around one hour per gallon
Overall Time: 15 to 60 days, depending on equipment and leaching methods