Fruit of the oak

The modern shouting match over sustainable eating—the furor over GMOs, food-miles and carbon footprints—has effectively buried one quiet but crucial perspective. From an ecological standpoint, annual agriculture (in both its conventional and organic forms) has been an unqualified disaster. Notwithstanding the petrochemical regime that has risen to dominance over the last two generations, the practice of annual tillage itself is problematic—severely impacting beneficial soil life, contributing to soil loss and releasing massive quantities of CO2 into the atmosphere.

Enter the humble acorn.

For as long as people and oak trees have coexisted, on every inhabited continent, we have sought nourishment and community under their canopies. Not too long ago in this area, acorns were a dietary staple. A natural stand of mature valley oak trees can yield several thousand pounds of acorns per acre in a good year (with some single trees found to produce more that 2,000 pounds), without soil amendments, tillage, or human labor of any kind. While by no means a silver bullet for all of society’s food-related ills, building a relationship with oak trees and their fruit can be one small lesson in a field of study that too often eludes our attention: how to be in a place.

I chose the valley oak for my recent experiment in acorn cuisine. There is probably one—tall, majestic, of deeply lobed leaves and of weeping habit (or shape)—on your block. The trees’ acorns are larger than those of the blue oak, but both are suitable for eating. Production cycles of the acorn can be inscrutable; whole regions may go several years without a significant crop. This is a heavy production year, what is known in botanical circles as a “mast” year. On a short walk by the creek, I gathered several pounds in a few minutes.

The shells of young acorns can be difficult to crack. I soon determined that pliers were worse than useless and switched to a carpet knife with a sharp blade, scoring a line down the length of the acorn’s shell; then I used my thumbnail to slip out the nuts. I discarded any obviously funky acorns, or those with a hole in the shell—the signature of the acorn weevil larva.

When I had a good pile of shelled acorns, I dropped them in multiple batches into a food processor with a little water, ending up with what looked like frothy chai. This I poured evenly into four one-quart Mason jars, which I then put in the fridge. This process, known as cold leaching, is paramount in making the acorn’s nutrition available. Bitter plant compounds known as tannins make unleached acorns indigestible. Soaking ground acorns draws out the tannins, freeing up the starch, fat and protein and eliminating the bitterness.

Every morning and night over the next five days I poured off the dark, acidic water, replaced it from the tap and gave each jar a vigorous shake. By the fifth day, the acorn meal had a bland taste, not bitter at all. To dry the meal, I poured the jars’ contents through a mesh strainer lined with several layers of cheesecloth. After squeezing out the remaining water, I ended up with something resembling brown sugar, which I then spread out onto two baking sheets. On my oven’s lowest setting (170 degrees), I baked the meal for about an hour, periodically pulling the baking sheets out to stir the meal around. Finally, I ran the dry acorn meal through an old coffee grinder I keep around for such things. The resulting flour was dark and aromatic, roughly the color of the discarded shells.

Far from bleak apocalypse fare, or pioneer-days anachronism, acorn flour has a deep and complex character and deserves a place at the modern foodie’s table. Having no gluten, it is best used in conjunction with wheat flour. For breakfast, I used the buckwheat pancake recipe in The Joy of Cooking. The pancakes were dark, with an incredible nutty, toasted flavor not unlike buckwheat; the texture was cake-like, with a mild crunch. Later my wife baked loaves of robust, delicious bread using the acorn flour.

If you’re up for an adventure in deep, tasty sustainability, grab a backpack and a friend and head to the park for some acorns. The universe will thank you for it.