How to eat tannins

If you live around oak trees, you

May find yourself looking out at an endless blanket of acorns on the ground, and you may ask yourself, "can i eat these?".

I mean, it seems like an ample

Supply of free food, and the squirrels sure do seem to dig them.

Yeah, you can eat acorns. They were a staple food back in our hunter-gatherer days, but there's a reason that agricultural societies have generally only eaten acorns in times of famine. The nuts of oak trees are, to varying degrees, toxic and gross, but you can process them to make them less toxic/gross. And certain oak species produce acorns that really aren't that bad right off the tree. "Not that bad" is high praise when it comes to acorns. Imagine you're an acorn falling from this dizzying height as I tell you that most oak species fall into the red oak group or the white oak group. The names come from how the wood looks when first cut, or some people say it comes from how the leaves look in the fall.

It's not easy to tell a white oak from a red oak, but this is a white oak, judging by the relatively rough bark, the rounded tips on its leaves, and the fact that its thin little acorns do not taste like straight poison. I mean, they don't taste great, still pretty bitter, but vaguely tolerable, I guess. I mean, there are places in this world where people eat acorns even when they're not starving, and predictably, those places generally have lots of white oak species. I'm talking Spain, Sardinia, parts of Italy where people eat roasted acorns voluntarily, generally from white oaks. And then you've got red oaks — slightly smoother bark, pointier leaves, fatter acorns, and these ones taste like straight poison. Remember, an acorn is a nut, so it's encased in an inedible hard shell. You have to smash your nuts to get to the oily meats inside, which taste pretty much like drain cleaner and could kill you if you ate a whole lot of them raw. The problem is tannins, a class of polyphenols that oak trees use to keep away pests and fungi and such.

"Tan" is an old Celtic word that just means oak. Ancient people knew that if you grind up the bark of an oak tree and dissolve it in some water, you end up with a bitter tea that has some interesting properties. It can function as an antidiarrheal in people who are really, really sick, if they drink a little bit of this bitter tea. And if you soak animal skins in this tea, you will convert them into leather. We call this tanning. A defining feature of tannins is they bond really easily to proteins, and when they bond to the collagen in skin, you get a surface that resists water and decomposition, and that is leather. But if you eat tannins, they bond to the proteins in your diet, rendering those proteins indigestible, and over time, you can end up with a nutritional deficiency disease from not getting all of your essential amino acids. Tannins are antinutrients.

And if you eat a whole lot of them, you can damage the lining of your gut. You can damage your kidneys, your liver. There's a reason that people evolved to really dislike the taste of tannins, at least in very heavy concentrations. In light concentrations, tannins are responsible for some pleasantly mild bitterness and astringency in red wine, tea, coffee. In Eastern Europe, they actually have a long tradition of using acorns as a coffee substitute. Having tasted acorn coffee myself, I can even more confidently endorse real coffee from.

You can see the germ inside here.

It won't sprout until the spring. This is probably why red oaks need way more tannins. The tannins keep away fungi and other things that could eat the acorn while it's lying on the ground all winter waiting to germinate. Squirrels know this. I mean, they probably don't literally know it, but they've evolved a preference for eating white oak acorns fresh and for storing red oak acorns in their little stockpiles for later. The red oak acorns don't go bad as fast in storage because tannins, and the squirrels usually only eat the top part of the acorn. The tannins are more concentrated in the bottom part where the germ is.

They don't eat the bottom part, and as a result, the acorn is often still able to sprout even though it's been eaten, and the squirrel was kind enough to take it far away from its parent tree to a clear spot. And in a clear spot, it's going to have a better chance of actually growing up. Co-evolution — it works. All of this is to say, if you're going to eat acorns, be like a squirrel and go for the white oak acorns first. Either way, you're still going to need to get the tannins out. Actually, you're first going to need to crack all the acorns and pick out the meats, which takes about as excruciatingly long as you would imagine. After that, you need to get the tannins out. One way is to mix the acorns with clay.

The Pomo people, indigenous to California, traditionally make little loaves of acorns, water and clay. They bake them for a really long time, and then they eat them, clay and all. Minerals in the clay adsorb the tannic acids, rendering them biologically inactive. There's a similar tradition in Sardinia. But if you live in a place with plenty of fresh water and you don't want to eat dirt, the better option is just to leach the tannins out. They are highly water soluble. Running water will do a better job, but you can just let the acorn sit in water overnight, pour off the water the next morning, and then you repeat for several days, several changes of water until the water runs clear and the acorns don't taste super bitter anymore. You can accelerate the process by pulverizing the acorns, though I fear you would lose a lot of nutrients when you pour off that water.

This is how you make milk from nuts, after all. You're throwing away the milk. You can also accelerate the process by boiling instead of soaking. It still took like four hours of boiling and several changes of water before these red oak acorns tasted even vaguely tolerable. Once you've got the tannins out, you can draw your acorns in the sun or in a low oven, use a hot oven to roast them, and now they smell really good, as roasted nuts generally do. They smell way better than they taste. Once cooled, you can grind these into acorn flour, though acorn flour is probably better if you cold-process the acorns. I boiled these, which cost me some starch.

Regardless, you can usually get away with replacing half of your wheat flour in any quick bread recipe with pretty much any other dry ingredients. So I'm guessing these pancakes are going to work. Not looking bad there, not looking bad at all. Famine never tasted so good, which is to say it still doesn't taste that good at all. But better than starvation. Acorns: maybe just leave them on the ground. This message brought to you by squirrels...