I no longer have my forest lot where I could collect tons of acorns, luckily via Facebook I can find people giving them away locally on occasion or I can find a good place to collect them as there is a foraging group that sometimes updates. I have trees near me, however, that should produce some acorns later in the season though I’m unsure how big that harvest will be as it will be my first year.
Acorn flour is probably the most convenient of the foraged flours I have available as the other wild flour sources simply aren’t here or aren’t planted, aside from wild rice. I’ve processed acorns a few times into flour more in a hobby way and as a tester to see if I could supplement part of my chicken feed as I was unsure how it would perform as baking flour. Surprisingly, the few experiments I did were delicious.
The process starts with gathering the acorns in fall, removing any acorns with signs of insects or rot, then grind the acorns with the tops removed, then you leach the acorns into flour. Acorns have tannins and they need to be leached out before ready for consumption.
There are several methods out there for leaching acorns, the two I’ve tried are the boiling method and the coldwater leaching method. I prefer coldwater leaching since it is simple and I can be lazy about it as well as it doesn’t alter the flour too much. The only real catch is you need plenty of fresh water.
How to Make Acorn Flour
First, you need oak trees or a supply of acorns. If you gather acorns by hand you want to avoid acorns showing signs of small holes or any rot, these will not be good for flour. The type of acorn doesn’t matter so much as the first goal is getting a large amount as you need some gallons of nuts to make a decent flour amount.
The next step is figuring out your method for cracking, I had a small nutcracker that worked and if need be I could bash them with a flat rock on a hard surface, like on concrete, another rock, or some cutting board you don’t care about.
It takes a bit of practice to crack them by bashing as I sent more than a couple of acorns flying across the yard, though with some experimenting with positioning and how hard you strike it isn’t too hard. Remove any shoddy acorns you might have missed during the first filter, if it looks nasty or has bug signs just throw it away.
Grinding Acorns For Flour
When all the acorns are cracked, you get to grind the nuts into flour. This isn’t hard and you can use any decent food processor to do it. In a pinch, I even used a really coffee grinder once as it gave me the finest grind I could manage as a general grind seemed to leave my flour very gritty instead of it all being fine.
You will want to divide your own flour into the fine flower and the “gritty” flour and work to get the leftover gritty flour fine.
Leaching Acorn Tannins
When the grind process is complete you basically need to give the acorns a long bath to leach. You add the flour to water and allow it to soak then change the water either every 12 hours or once a day.
You simply mix half flour with half water, allow to soak. Then pour off the water when you need to change it and keep from pouring out the flour that sits at the bottom. Then fill the water back up and store it in someplace out of the way where you will remember to tend to it.
Keep doing this routine for around 3 days. After 3 days you can test your flour and it should be pleasant and sweet. You want zero tannin taste. If it takes more days, then work the flour more days.
Drying Acorn Flour
When I dried my flour I used a strainer that was fine mesh enough or cheesecloth and then spread the wet mush onto my dehydrator sheet meant for making fruit leather. I’d let it slowly dry on the lowest setting then move to a storage can and then dry more flour until it was all dry. Some people use extremely low heat and dry it by putting it on a baking sheet in the oven. Others spread the flour on sheets and let it dry from the sun. Whatever the method, you want it to dry completely or it will spoil rapidly.
The resulting flour will store for some months in a pantry unless you opt to freeze it. As acorns are a nut and it is nut flour, the nut oils will go rancid at some point. It helps to only make as much flour as you can use in a few months and keep the rest of your acorns stored whole and not processed.
Keeping some acorns sitting around whole also gives you a supply you can use for crafting.
Cooking With Acorn Flour
Acorn flour doesn’t quite cook up the same as white flour. When I experimented with it I either used it for things like a cake or a quick bread or used it as just a partial amount of the flour mixed with wheat flour. The main thing is the resulting bread won’t be very fluffy or at least that is my early observation and this all needs further experimentation.
There are a lot of other sites and a lot of other books that have recipes for acorn flour, so with some digging, there is a lot evidently possible. I’ll expand on this as I try the flour and test recipes again.