Hot leaching is a quick way to remove the tannins from your shelled acorns. However, since hot leaching acorns cooks the starch in the nuts, they’ll require an extra binder to hold together in baked goods. If you’re making acorn flour for baking, cold leaching is a better choice.
But hot-leached acorns are still useful! My favorite way to use hot leached acorns is as a soup base, but they also make an excellent stuffing ingredient and a tasty base for felafel or a meatless burger.
Before you leach your acorns, taste an unleached nut. Yes, it will be bitter, but it will give you a baseline flavor, so you can monitor your progress as you leach the tannins from the acorns.
To hot leach acorns, fill a large pot one third full with shelled nuts, then cover them with an equal volume of water. Bring the water to a boil, and boil until the water turns dark brown. Pour off the water, and repeat the process several times.
Some written accounts say to do this until the boiling water stays clear, but that may never happen. I’ve found that the water still has color long after all bitterness has been leached from the nuts. Instead, start tasting the acorns after the third or fourth change of water. When there’s no trace of bitterness, your nuts are leached. Depending on the acorn, this may be as many as 15 changes of water.
You may also read that acorns must be moved from one pot of boiling water to another, rather than out of boiling water into cold water that is brought to the boil. Some foragers swear that cold water sets the tannins in the nuts, making them permanently bitter, but others have not found this to be true. I’ve done it both ways and honestly I can’t say there’s a difference. In my experience, cold water does not permanently set the tannins. Hot leached acorns brought to a boil from cold water are perfectly palatable, as long as they are leached in sufficient changes of water.
After all the boiling, hot leached acorns will be darker in color than cold leached acorns. They can be coarsely ground and used as nuts in cookies and breads, and also make an excellent soup: hearty and thick on a cold autumn evening.
Allison Fink says
Thank you. I’ve been trying to leach acorns that were fairly sweet to began with an the water kept getting darker. I guess I needed the permission of the internet to just stop. 🙂
Trust your taste buds!
I have a question. I tried to cold leach. but since i put several batches together that took a week of difference to gather, I leached them for OVER 10 days. changing the water around 4-7 times a day.
They were still bitter as hell!! so i thought hot leaching would be quick since they were in cold water for so long. but it took about 5 hours. several water changes. and still. they are almost bland but i still get bitter aftertaste. what did I do wrong ? could they just be extra spicy ? lol. they are dehydrating now before I crush them. but I have another few batches to go. hoping the get the next ones right.
Well since I wasn’t there, I can’t tell you where you went wrong! It sounds like you did everything right, but these are my thoughts/questions 1) How finely did you grind the acorns? They need to be about the size of grits. 2) If you’re doing a super large batch, the water may not have reached the interior of the mass of ground nuts to leach. I ask because you said you combined bathces. 3) Did you pour out as much water as possible every time you changed it? 4) Are they red oak acorns (which are usually more bitter than white oak acorns), 5) Are you especially sensitive to bitter flavors? Those are my first thoughts.