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In the United States, there are quite a few different species of oak trees, and many of them vary by climate and region. The important thing is, however, that if it’s an acorn, it’s edible, no matter what species it comes from.
In our area of the Ozarks, we seem to be dominated by white oaks, but you may find that the oaks that populate your region are quite different. Regardless, the process of collecting, processing, and eating is much the same.
The first thing to consider when foraging for acorns is the timing. Oaks have two distinct phases when they drop acorns. An early drop and then the good drop. Early in the fall, you may notice that oak trees are dripping with acorns for the first time – this is not the time to collect nuts.
If you collect from the first fall, you’ll be disappointed to find that every single one is bad. In some, inexplicable way, oak trees know what nuts aren’t developing well or are infected with insects, and so they rid themselves of the unworthy nuts as soon as they can. Many of these acorns will still have their caps firmly attached (a sure sign of a bad nut).
It’s the second drop you want to watch for, usually happening sometime in October. These nuts are the good ones! You can crack open a few acorns with a rock to test them
Now, there are some options when it comes to gathering. At the beginning hunker down under the most productive oak trees and pick up acorns by hand. It’s quite easy to sort through acorns by sight.
How to tell a good acorn from a bad one? It basically comes down to inspecting the disc on the top for dark marks, watching for weevil holes, and ignoring ones with the caps still attached.
A much faster approach is to use the Garden Weasel Nut Gatherer.
Though the collecting tool is indiscriminate in whether it’s picking up a good acorn, rotten acorn, or rock, the time it saves in not having to bend over and the speed of gathering made it totally worth using. Under a good tree, you could fill a five-gallon bucket in under an hour! Granted, there will be the odd stick and stone in your pail, but you can easily sorted those out when you get back inside and began to process the nuts.
Once you have your haul of nuts, it’s important to get them drying or processed as soon as possible. Since acorns are naturally rather moist, they can go bad really quickly when piled in a bucket.
If you can’t process them immediately, lay them out flat in a single layer somewhere where air can circulate around them.
Also, be aware that acorn weevil larvae will appear soon – even some good-looking nuts are secretly host to the little grubby nut-destroyers.
The grubs are not harmful in the least, as they can’t re-infect other acorns, and they don’t bite. Be aware that the grubs’ sole desire is to get back into the ground so that they can pupate and infect next year’s crop of acorns. It might be best to dispose of them somewhere far from your choice oak trees.
The first step to process your acorns is to wash them. Filled your kitchen sink with half full with water and dump several scoops of acorns into it. Immediately, most of the acorns dropped to the bottom. These are likely to be good.
You’ll find that the acorn caps and many bad acorns float on the surface – this makes the first step of sorting quite easy! Take note, however, that almost all dried acorns will float, so if you dry your acorns before processing them, the float test won’t be useful to you.
All the acorns that looked good should be spread out in a single layer on several cookie sheets. Toast them in the oven at 175 degrees Fahrenheit for an hour and a half. This serves to dry them off and warm them for cracking.
Now, there are several options when it comes to cracking loads of acorns. It can be as simple as smashing them open with a hammer on a flat surface or as sophisticated as buying a specialized nutcracker for the purpose.
Anysell88 Manual Heavy Duty Rocket Nut Cracker (https://www.amazon.com/Anysell88-Manual-Cracker-Nutcracker-Sheller/dp/B07GZCVCBM/ref=sr_1_1?s=home-garden&ie=UTF8&qid=1537112237&sr=1-1&keywords=anysell88+manual+heavy+duty+rocket+nutcracker)
During this stage that do the bulk of your sorting. It’s inevitable that some bad acorns will ride along with the good ones, but once they’re cracked open, the good is super-easy to separate from the bad.
Any that were moldy, had clear evidence of being nibbled by bugs or were covered with dark spots go into the compost, and all the tan, waxy, nutmeats go into a large stock pot so that they can be leached.
During this stage, most of the testas (the dark brown, papery coating over the nut) also comes off. Some sources say that you must remove every trace of the testa to have tasty flour, but the odd piece here and there really doesn’t make a difference.
This next part is important. It’s possible to eat a single acorn raw with no ill effect, but I don’t know if you’d want to repeat the experience. The high amount of tannins in acorns make the raw product quite unpalatable. Leaching – soaking the acorns in water to separate the nut from its water-soluble tannins – makes them edible!
Cold leaching acorns results in a versatile end product, one that can be used as a fine flour or coarse polenta, as well as in all the ways you can use hot leached acorns. Acorn flour doesn’t have gluten in it, but it’s a versatile flour, nonetheless, especially when the tannins are leached with cold water.
Because it contains no gluten, acorn flour won’t rise on its own. That’s why you’ll often see recipes calling for half acorn flour and half regular flour. However, some baked goods, like cookies and brownies, work well with cold-leached acorn flour alone. Acorn flour adds richness and depth to anything you use it in. The starch you preserve by cold leaching helps bind the baked goods and lets you use your acorn flour in lots of different ways.
Native peoples used to let running water do the work of leaching by tethering baskets of acorns in a stream and allowing the cold water to run through the nuts for several days. I don’t have a stream, but I do have a toilet tank.
The Jar Method for cold leaching acorns.
It’s low tech, and requires only a little more effort on your part. For this method, you’ll need to grind your shelled acorns into a coarse meal before leaching. You can do this in a high quality blender, like a Vitamix, or with a hand mill, sold for grinding whole corn kernels. A hand mill produces a coarse grind, which is perfect for recipes like falafel and veggie burgers, while the Vitamix produces a finer flour, excellent for baking.
Find a large, clear glass or plastic jar with a tight-fitting lid. Fill the jar halfway with coarsely ground acorn meal, then top it off with tap water. Use a chopstick or the handle of a wooden spoon to poke out any air pockets in the acorn meal, close the lid, and give the jar a good shake. Move the jar to the refrigerator. The acorn meal will settle out of the water with time, and the water turns brown as the tannins leach from the nuts.
Let the jar sit for 24 hours in the refrigerator, then carefully pour the water off the meal. Don’t worry about getting every last drop. Refill the jar with water, and replace the jar in the refrigerator. You’ll need to do this several times, depending on how bitter the nuts were to begin with. After pouring off the water for the third time, taste the acorn meal. If it’s bitter, continue to change the water every 24 hours until no trace of bitterness remains.
Once the bitterness has been leached from the acorn meal, pour the meal out into the center of a dish towel. Gather the four corners of the towel together and twist the dish towel closed, then continue to twist until water begins to drip from the bottom of the dish towel. When no more water can be removed by twisting, squeeze the dish towel as hard as possible to remove as much water as you can.
If you’re in a big hurry for leached acorn flour, try the running water method. This is the most labor-intensive method, but is by no means difficult. Put a cup of shelled nuts in a blender and add water to four to five inches above the level of the nuts. Pulverize to create a slurry, and set aside. (If you have already ground your acorns into meal, but not yet leached them, you can also use the method described below.)
Place a large colander in the sink and line it with a dishtowel. Pour the slurry or meal into the colander, then run cool water into the colander and stir with a large spoon. After eight minutes of stirring, taste the slurry. If there is any bitter flavor, let the water run for another two or three minutes and taste again. You should be able to stir without spilling, which is why this is best done in small batches in a large colander. Once the acorn meal is not at all bitter, squeeze out as much excess water as possible, as described in the jar method, above.
If you have a dehydrator with fruit leather sheets, spread the moist acorn meal across the sheets and set the temperature to the lowest possible setting. Depending on the humidity where you live, your meal will take between 12 and 24 hours to dry. Check it after several hours and break up any large clumps to speed the drying process. An oven or warming drawer will also work, as long as the temperature is below 150F.
You can stop here, at the dried acorn meal stage, or grind it to make a fine flour for baking. The dry grains canister of a Vitamix does a great job in under a minute, but an ordinary spice grinder also does a very good job, albeit in smaller batches. I like to keep jars of both coarse meal and fine flour on hand.
Once the acorns (whole or ground) have dried, they’re ready to be measured, sealed, and stored. A vacuum sealer is a handy tool for preserving freshness, but if you don’t have a vacuum sealer you can store your leached acorns in ziplock bags. Close the bags most of the way, then suck out as much air as you can with a drinking straw before sealing them all the way.
Whole nuts will keep for several years in the freezer; the smaller amount of exposed surface area means slower oxidation. Flour and meal should be used within a year.
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