Guide to Cold Leaching and Preserving Acorn Flour

[230gr]

Guide to Cold Leaching and Preserving Acorn Flour
Shell Your Acorns
Placed a few nuts at a time between in a heavy plastic bag and cracked them with a rubber mallet. Acorn shells aren't very thick and cracking them is easy
Choose a Leaching Method
Shelled acorns must be leached of their tannins before they can be eaten. Unleached acorns not only taste terrible but consuming large amounts of tannins reduces the efficiency with which your intestines absorb nutrition.
How you leach your acorns depends on how you want to use your nuts.
•   Hot leaching (boiling) cooks the starch in the nuts, meaning they won't bind well as a flour. However, hot leaching is fast, and if you plan to use your acorns as snacking nuts or as a soup base, this is a good way to go.
•   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. And when it comes to cold leaching, you have choices.
Cold Leaching Method # 1: The Toilet Tank
Native peoples let a running stream 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. You can simulate this using a toilet tank and putting the shelled acorns in cheesecloth bag in the clean tank. Each time you flush the toilet, cold water washes through the acorns, gradually leaching them of their bitterness. How long it takes before your acorns are palatable will depend on what kind of acorns you have and how often you flush your toilet. Taste a nut every 24 hours, and when there's no bitter aftertaste, your acorns are ready!
Dehydrating Whole Nuts
After leaching, dry the acorns in a dehydrator, on the lowest possible temperature, below 150oF so as not to cook the starch. Dehydration may take up to 24 hours, depending on your method. Red oak acorns require an extra step at this point. They have a thin skin called a testa, located between the nut meat and the shell. White acorns don't. Hot leaching removes the testas, which have a bitter taste. If you cold leach, you'll need to rub off the testas before you cook with your acorns. Fortunately, after drying, the testas fall away with a gentle rubbing.
Dehydrated, leached acorns can be ground into flour right away, or cool stored whole. Acorns are high in fat, which may turn rancid if stored at room temperature.   
Cold Method Leaching # 2: The Jar Method
For this method, you'll need to grind your shelled acorns into a coarse meal before leaching,  then soak the acorn meal in several changes of water in clear glass or plastic jar with a tight-fitting lid. Fill the jar about halfway with coarsely ground acorn meal, then top it off with tap water. Use the handle of a wooden spoon to eliminate any air pockets in the acorn meal, close the lid, and give the jar a good shake. Move the jar to the cool place. The acorn meal settles with time, and the water takes on a dark brown color as the tannins begin to leach from the nuts. Let the jar sit for 24 hours, then carefully pour the water off the meal. Refill the jar with water, and replace the jar in a cool place. 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.   
Squeeze out Excess Water
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 possible. This may take several minutes.
At this point, you can freeze the moist acorn meal as is, but you'll need to use slightly less liquid in any recipe you make with the flour.
Dehydrate the Acorn Meal
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.
Keep the temperature is below 150oF. You can stop here, at the dried acorn meal stage, or grind it to make a fine flour for baking.
Once the acorns (whole or ground) have dried, they're ready to be sealed, and stored. A vacuum sealer is a handy tool for storing whole nuts, meal, or flour. 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.

What Can You Make with Acorn Flour?
Acorn flour doesn't have gluten in it, but the starch you have preserved by cold leaching helps bind the flour, but it will never behave exactly the way wheat flour does. You can substitute acorn flour for up to half the all-purpose flour called for in most baking recipes. It adds depth and richness to this brown bread recipe and also makes tasty muffins, and pancakes. Use coarsely ground acorn meal as a soup base and to thicken stews.

https://www.thespruce.com/cold-leaching-and-preserving-acorn-flour-4007438