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If you haven’t read my other acorn posts, Acorns and the Forager’s Dilemma is an introduction to the use of acorns; the Forager’s Dilemma is, in a word, starch. Starch (carbohydrates) is the toughest thing to forage for, and is a primary reason why humans settled down 10,000 years ago to grow grain. Next I wrote about an interesting Acorn Honey Cake I’d made and how various world cultures have traditionally used acorns, cultures ranging from Korea to Japan to the Native Americans, Europeans and North Africans.
Using acorns as food pretty much falls into three categories: Eating acorns as nuts (they are a lot like chestnuts), making acorn flour, or cooking in acorn oil. I have not yet tried to make acorn oil, but I know how to do it and plan on trying it when I am a bit more mobile.
COLLECTING ACORNS
First you need to get yourself a supply of acorns. Go find some oak trees; they’re the ones with all the acorns that have fallen down around them. I know this sounds condescending and stupid, but oaks come in so many varieties that in autumn this really is the easiest way. It is a bit of a crapshoot, as it is tougher to determine a variety of oak by its acorn than by its the leaf — you can do it, but it is a little harder.
You can gather acorns anytime from September until early spring. I find gathering as the acorns fall is best. Suellen Ocean, who wrote a very useful book Acorns and Eat ’em,
says she likes to collect Tanoak acorns in February and March, after many have begun sprouting. She says acorns with sprouts between 1 to 2 inches long are still good to eat, but discard any acorn meats that have turned green. Ocean says recently sprouted acorns a) have begun to turn their starch into sugar, and b) are foolproof: “If it is sprouted, it’s a good acorn and I haven’t wasted time gathering wormy ones.”
A word on worms. When I first gathered acorns, little did I know that I had gathered scores already infected with the larva of the oak weevil. Nasty little maggoty things, you can tell they are inside your acorn if there is a little hole in the shell. Look for it, discard that acorn and move on. But know that oak weevil larvae bored those holes from the inside out. Like Alien.
It’s helpful to know what kind of oak you are dealing with because acorns from different oaks have different levels of tannins in them; more on that in a bit. If you don’t know your trees, start looking for little green acorns in May. Pick a leaf and compare it to oak leaves online or in a guidebook. Gather acorns and compare them to online images and guidebooks; different oaks bear acorns with different shapes. With that in mind, remember that not all oaks are created equal, and the fundamental fact of cooking with acorns is that you are dealing with a wild food, and as such must contend with tremendous variability, both in species and even among individuals of the same species.
Some oaks bear acorns so low in bitter tannins that they can be eaten raw. Legend says that California Indians fought over these trees, which makes some sense because one mature Valley Oak can drop 2,000 pounds of acorns in a really good year. A ton of sweet acorns may well be worth fighting over. That said, even “sweet” acorns should be leached to remove what tannins exist in them because several studies show that unleached acorns can make you constipated and can harm your teeth. Of all the species I know of, only the imported European cork oak and the Emory oak of the Desert come close to being “sweet.”
Tannins aren’t the only thing that makes different species of acorn different. UC Riverside Professor David Bainbridge wrote in a 1986 academic paper that depending on species, acorns can range in fat content from 1.1 percent to 31.3 percent, protein from 2.3 percent to 8.6 percent, and carbohydrates from 32.7 percent to 89.7 percent. That is a huge range!
What does it mean? It means that in the kitchen you treat acorns from different species very, very differently. A fatty acorn will make a meal, like ground almonds. A carb-rich acorn — like Valley Oak acorns — makes a drier flour, more like chestnut or chickpea flour (acorns lack gluten and so will not rise.)
WHAT TO DO WITH VARIOUS OAKS
Here’s a general breakdown:
‘Sweetest’ Acorns, meaning lowest in tannin: East Coast White oak, the Emory oak of the Southwest, the Pin oak of the South, the Valley and Blue oaks of California, the Burr oak of the Midwest, as well as the Cork oak and the well-named Bellota oak of Europe. To my California readers, know that there are an awful lot of cork oaks and burr oaks planted in towns and cities here, so keep your eyes peeled.
Largest Acorns: Valley oaks are really big, as are East Coast White oaks. Burr oaks are large, too, as is the California Black oak.
Fattiest Acorns: The Eastern red oak acorns I’ve used have a very high oil content, and I’ve read that the Algonquin Indians used red oak acorns for oil. In the West, the champions are both live oaks, the Coastal and the interior live oak, as well as the tanoak and black oak, which is Quercus kellogii.
SHELLING
I found that shelling the acorns is the most onerous part of dealing with them. They have an elastic shell that resists normal nut crackers. I found whacking them with a hammer to be the best way to open up an acorn. Some people use a knife, and I do this with green acorns, but not fully ripe ones. Best way to whack ’em is to put the flat end (the side that used to have the cap) on a firm surface and rap the pointy end with a hammer, or, with long, tapered acorns like cork oak or Valley oaks, just whack the side.
Acorns are far easier to shell after they’ve dried. If you choose to dry them, do this in wide, shallow pans so they don’t get moldy. Once dried, I’ve worked with two-year-old acorns and they were fine.
Red oak acorns have a “test,” a skin that doesn’t want to come off, just like a chestnut. If you boil the acorns and shell them while still hot, the skin comes right off. Only do 5 to 10 acorns at a time if you are doing this, or they’ll cool too much. I only bother with this when I am making acorn bits, not flour. The skin is a little bitter, but it’s not that big a deal if you are making flour.
Shell your acorns into water. The meats oxidize fast, and you will get a lighter-colored flour if you do this. It’s aesthetic, but it matters to me.
TANNINS
All acorns should be leached with water to remove bitter tannins, which will a) make your mouth feel and taste like felt, b) make you a bit nauseous, and possibly c) constipate you for days.
Getting those tannins out is the big barrier to cooking with acorns. But it ain’t no biggie. With my Valley oak acorns, after shelling I drop the acorn meats directly into my stockpot that was two-thirds full of water. When I fill the pot about a third of the way up with shelled acorns, if I am in a hurry, I bring the pot of water to a boil. The water turns dark. As soon as it boils, pour the water off into the sink and repeat the process. It requires about five changes of water to get Valley oak acorns to taste like chestnuts. I did this all while watching football, and did not miss a snap. Other oaks will require more or fewer changes of water. Choose the “sweetest” acorns on my list above for the least amount of work.
There is a better method, but it takes days. Grind the raw acorns into flour, then mix 1 cup of acorn meal to 3 cups water. Pour this all into a glass jar with a lid and put it in the fridge. Every day you shake the jar, wait 12 hours or more, then pour off the water — and the tannins. How long? Anywhere from a week to two weeks, depending on how bitter your acorns are. This is a good way to leach acorns without using fuel for boiling water, and you do not denature a particular starch in the acorns that acts a little like the gluten in flour, i.e., it helps the flour stick to itself. I go into the full process of cold leaching acorns here.
If you plan on baking with the acorn flour, use the cold-water leaching method.
Once your acorns are free of tannins, you need to figure out what to do with them. Regardless, you need to dry them first or they will rot. Big pieces can be patted dry on a tea towel. If it is hot out, lay the acorns out on cookie sheets and dry in the sun. You could also put them in an oven set on “warm.” You can also put the acorns in a dehydrator set on low heat.
You can also freeze your fresh acorn meal. Store dried flour in jars in the fridge. Why the fridge? What fat there is in acorns will go rancid pretty quick if you left the flour at room temperature.
What you can now do with this flour is pretty limitless. My first success was an acorn flour flatbread in the style of an Italian piadina, which is essentially a tortilla. I then made acorn flour honey cake, which is really very tasty — almost like gingerbread cake. The flour also makes an excellent pasta dough when mixed with regular flour.
Thank you this is Fab – one question – as acorns are regarded as ‘nuts’ and therefore a Protein?.. so in making bread from the flour, would it be classed as the first real Protein bread?
I ask this as I sometimes follow the Hay diet which is separating your proteins and carbs and eating them as a full protein or full carb meal on alternative mealtimes – (this is because the digestive juices in your stomach swop for each type, and can only really handle one at a time, and if you mix them your digestion will take days instead of hours longer etc, etc ) A ‘Protein’ based bread would be totally fab and could be eaten with other pure proteins ? Thanks !
All the Best x
I live in New England. We have small green acorns, can we use those as well ?
I am processing acorns for the first time. I disgarded the ones that floated, had a hole, or was dark or deformed inside the shell. My question: Many of the acorns have a small black squiggle line on the outside of the meat. It does not go deep into the meat. Is this okay? I gathered six pounds, tossed three pounds due to floating/holes, and then tossed about half of what was left because the meat was bad. If I tossed the ones with the small line, I would toss another 80 to 90% of what is left. What is the line? Is it ok?
Oh, and I meant to make note, but forgot in the process of thinking what else to say, that everyone else who’s taken up grain agriculture has done so by dint of enforced cultural change. They were converted into the act, rather than coming to it on their own. That says something. All along, when anybody bothered recording their words, indigenous people faced with being made to settle down to grow huge fields of grain largely resisted the idea, not seeing the point when there was so much other food in the world they could gather or hunt instead.
There *is* quite a lot of food in the world, you know. Just because we refuse to see it as food doesn’t change the fact it’s edible.
Actually, there is no human dietary need for starch, and it is highly likely that the people of the Fertile Crescent in Iraq developed grain agriculture in order to *brew more beer.*
There have been all of three major centers of agricultural development on the entire planet: one in Iraq, one in China and another in Mesoamerica. Everyone else has found that growing or foraging tubers or eating nuts more than sufficed, when they bothered with starch at all.
It makes no sense, anyway, to develop agriculture for the purpose of fending off starvation. It’d be like sewing a parachute after jumping out of the plane barebacked. And perpetuating the myth that agriculture somehow saved us from a fate worse than death is harmful in terms of being able to move on from this incredibly destructive practice (all the grains are grass, which can only grow in unforested or deforested areas, which contributes directly to global warming) and find better ways of obtaining plant foods which are not so taxing on the biosphere.
You’ve got a good start here with the acorns, anyway. If I wanted to eat that much starch–and I don’t; the tendency to type 2 diabetes is strong in my mother’s family, and I’d only put myself at greater risk.
Thank you very much for such a wonderful and educational write up on acorns.
I just did a write up on the wild edible plant, the White Oak tree, in which I linked your website due to the wonderful amount of information!
Please take a look when you have time:
https://blog.emergencyoutdoors.com/edible-wild-plants-white-oak-quercus-alba/
Thanks again,
Sara
Agamemnon: Yes they do, otherwise the oil will be bitter.
Hank,
I would like to press some acorns for cooking oil. You say that you know how. My question is do they need to be leached prior to pressing? Thank you!
I’ve been drying acorns, and found that my handheld metal garlic press works great for cracking the shells!
Fascinating post. I love process stuff like this. You were certainly ambitious in this project. I just had a go round with chestnuts here. Not nearly as exotic as your acorn endeavor 😉
I am have been looking for the best way to make Acorn Oil. And am having a hard time. Would you be able to give me any suggestions. Thank You.
Hi Hank,
I really love your blog, I’ve tried so many of your recipes now…
I wanted to share a few things I’ve learned about acorns, which I’ve been experimenting with for the last few years. I use mostly tanoaks, which produce in abundance where I live along the Trinity river. I like their flavor the best out of what I’ve tried, as well.
Julia Parker’s method (in the book “It Will Live Forever”) is definitely more work, but in my opinion, well worth it. my experience has been that the flesh of the acorns oxidizes rapidly, and it changes their flavor completely. the dry flour/cold running water leach keeps them from oxidizing if you use the leached, wet flour right away. if you’ve never tried it, it takes some effort to get it right, but you’ll discover a sublime and complex flavor – sweet and buttery – you didn’t know acorns had.
my experience with leaching with the jar-in-the-fridge method is that when you change the leaching water, the fat rises to the top like in milk, and you end up pouring off the fat with the tannins and the resulting flour tends to be bland compared to the running water method. if I wanted a tasteless starch filler, I might use this method, but not otherwise.
changes of boiling water is definitely easier, and the flavor produced by this method has its own merits, but again it’s very different from the fresh cold water method. I prefer it for soups and other uses where the almost mushroomy flavor is of benefit.
my favorite use for acorn paste fresh from the leaching basin? nun’s farts or cream puffs. you can make a perfect pâte à choux with 100% acorn flour, and when it’s fresh, the buttery, sweet and slightly nutty flavor is magic all by itself.
keep up the good work! I’m waiting for a recipe for bear salami…
Hank:
Still looking for Acorn Oil. Have you done anything to figure out how to get it out of the acorn? The only thing I know of is the Piteba Oil Press, and it’s less than perfect.
Wow. This post is an incredible reference. Thanks.
I tried the hammer to break shell, but it was then tedious to pull pieces out of shell. Instead , I cut top off and pealed off shell with my fingernails. This worked much better, and I got whole nut this way.
A reader named Kevin, who clearly knows his oaks, sent this along:
…another reason for white oak acorns to be readily eaten versus red oak acorns is that they sprout in the fall, leading to “spoilage”. The red oaks require overwintering (stratification) in order to sprout, and thus are cached. I’m not trying to go out on a dendrology lesson or anything since you may very well know this and it could be in your book; which is AWESOME! I don’t yet own a copy but i believe a certain someone is about to gift me with one.
Another interesting oak ecology factoid is that the white oak acorns don’t get dispersed very far from the parent tree (since they are not cached) and the subsequent seedlings are fairly shade tolerant for awhile. The red oak acorns are often dispersed relatively far from the parent tree (cached) and happen to be mostly shade intolerant. Did the acorn predators over time lead to the pattern of shade tolerance levels? I get giddy when it comes to oak talk, so I’ll excuse myself…
Cool stuff!
Hi Hank,
I’m a raw foodest, very new to foraging. I have alot of mature green acorns that have fallen on my property due to the hurricane. Due to the work involved in soaking the acorns, I am definitely going to use the toilet tank method to soak/rinse over at least four days. Is this the correct thing to do with these? All the pictures I’m finding online show beautiful brown acorns, so I think I’m missing something–also, do you know if these mature green ones would be better sprouted in a jar?
Hi,
Great thread by the way….
Last fall I spent a good deal of time collecting acorns. I shelled, boiled, and froze several bags, and am only now getting around to using them in recipes. My girl friend and I ground some up and made great acorn muffins!!! Yum Yum….a little maple syrup, with the traditional ingredients….
Anyway, so I am now wondering about the best way to store the acorn flower. It still seems a bit damp….I have it in an old, empty, coffee container….but I am worried mold might show up.
What would be the best way to make sure mold stays away?
Jason
I just found this post, very nice. A bit of warning though, we have a current problem with oak tress in southern California an insect called an oak borer. The infestation is growing. As I collect acorns yearly, I have run into the problem of making sure the trees are not treated for this insect. I have been told that the effects of the treatment on the acorns is unknown and therefore we do not gather from them if we know they are treated. Also transporting any part of oaks, wood etc, is no longer permitted as it will spread the infestation.
As for coffee, this is a traditional drink in southern California and northern Baja California. It is absolutely delicious, but the lower tannin acorns are preferred. See our mention of it in a calendar that we produced https://deborahsmall.files.wordpress.com/2009/12/ethnobotany-calendar-2010.pdf
You answered my Google question, which was can you gather acorns in spring. We live next to a large area of state forest in Connecticut – oaks and acorns everywhere. Thanks so much for the informative post. I’m going to give acorns a try. Someone once told me that white oak acorns make a great coffee substitute. Any experience with that?