How to Make Acorn Flour

By The Oaec Collective With Olivia Rathbone
Published on September 23, 2015
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Photo by Brock Dolman
Be sure to leach acorns until all the bitter tannins are removed from your acorn flour.

A weekend convergence at OAEC sponsored by the Cultural Conservancy called Decolonizing Our Bodies, Nourishing Our Spirits: Native Foods Think Tank, brought together cultural leaders, scholars, activists, and chefs representing 15 US and Canadian tribes to explore the importance of the restoration of Native foods to community health. Miwok cultural representative Julia Parker demonstrated both traditional and modern acorn preparation methods that we continue to practice whenever we get the chance.

Gather acorns when you notice they are dropping, usually from September to December. Collect only large, dense acorns, passing up those that have obvious weevil holes or that are unusually light. Immediately when you get home, dump them into a large bucket of water–discard (compost or burn in your fireplace) the ones that float, keeping the ones that sink. For maximum yield, you can put them all in the freezer–this will kill any remaining weevils. If you do not have time to immediately proceed to the cracking and leaching step, dry them to prevent molding and sprouting. Spread the good acorns on a flat surface in the sun to dry, or put them on a cookie sheet and place in a very low oven for a few hours (even just the pilot light should be sufficient). Store in a basket with plenty of airflow until you’re ready to proceed. According to California Native traditions, acorns are stored with boughs of California bay leaves, a natural antimicrobial, to prevent molding.

Crack the acorns. If you don’t have a traditional grinding stone or mortar and pestle, you can improvise by cracking the acorns briskly between a heavy object and a hard surface–say, a piece of firewood or cast-iron skillet against a butcher block. Pick out the nutmeats, discarding any that are moldy.

Acorns must be leached. Eating excessive amounts of tannins contained in raw, unleached acorns can be poisonous for humans.

There are many traditional and modern options for leaching, depending upon your setup and how you wish to use them. Julia Parker explained the construction of a traditional sand filter that leaches the acorn meal in a sandbar within a clean running stream–a rarity given modern-day pollution; hence, she offered a garden hose alternative. Below is an adapted version we’ve used in the kitchen.

Grind the dry nutmeats finely by hand in a mortar and pestle or with a grain grinder. Or process in a food processor or high-powered blender with plenty of water (1 part acorn to 6 parts water, give or take) until a thin slurry forms. Strain this into some kind of permeable cloth sack–a fine cheesecloth bag, the toe of a clean pair of tights, or the sleeve of an old shirt with the end knotted off. Proceed with leaching.

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