Acorn: the Perennial Grain
By Kyle Keegan
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Oaks, of the genus Quercus, are widely distributed over the temperate parts of Europe, Asia, North Africa, and North America. Their edible nuts, acorns, were a reliable staple food of many cultures before the beginnings of agriculture. Even today, acorns are sold in the markets of Korea, China, North Africa, and in some major cities of the US .
Growing staple crops on marginal land has been an age-old struggle. Carbohydrates, the source of basic energy, drive many of life’s processes and are a basis for survival. However, most agricultural practices that rely on annual plants contribute to the destruction of fertile soils. Over-tillage as practiced by modern farmers results in the loss of soil carbon and soil biodiversity. In contrast, long-lived oak trees provide not only sustenance, but also stabilize soils and climate while offering shade, shelter, fuel, and medicine.
Thus, a perennial-based agriculture should be the aim for any civilization seeking solutions to the problems of excess tillage and fertilizer inputs—problems long associated with annual crops. Some evidence suggests that modern annual agriculture may be directly related to the past mismanagement and destruction of oak woodland ecosystems worldwide. (1) Remaining oak woodlands may provide the most elegant model for a perennial polyculture in temperate North America.
Unlike corn, barley, wheat, or rice, acorn requires no tillage, and neither fertilizer inputs nor irrigation. Acorns are relatively simple to collect, store, and process, and they provide a nutrient-rich source of food for humans. The trees sequester carbon, moderate climate, build soil, stabilize hillsides, and provide essential habitat for hundreds of species of animals. (2) Oaks can be grown on steep or unstable land where annual crops would lead to erosion. Most species of oak can be grown in arid or semi-arid landscapes where annual grain crops would be problematic.
The yields of acorn compare well with those of many grains; established oak woodland has been recorded to yield up to 6,000 lbs. of acorn per acre. (3) Sadly, the health of many oak woodlands is impaired by the loss or lack of indigenous management (including prescribed burning). As a consequence, acorn production has declined and crop yield has become less consistent. (4, 5, 6)
Acorn was a staple food for most of California’s indigenous cultures. It is a rich source of carbohydrate as well as protein, essential amino acids, trace minerals, and vitamins (especially A and C). California Quercus spp range from 3-5% protein, 4-9% fat, and 38-69% carbohydrate. (7) Producing acorn flour takes time and energy, but the processing input is probably less than that for a cereal crop, while the nutritional value of acorn compares favorably with wheat or barley. The quality and flavor of acorn oil is reportedly comparable to olive oil, and the residual nut meal can still be used as animal fodder after the acorns have been pressed for oil.
What were we thinking?
Thirteen years after moving onto our rural land, my family began to focus attention on the staple food crop that had sustained native Californians for over 10,000 years. It now seems silly that for over a decade we walked a narrow winding path through a thriving perennial polyculture (oak woodland), stepping on or over an exceptional food source (acorns), to get to our cultivated crops!
Dana and Kaliana prepare tan oak (Notholithocarpus densiflorus) acorns, Fall 2010, Salmon Creek, Humboldt Co., CA.
This past fall, thousands of tan oak (Notholithocarpus densiflorus) acorns fell on our driveway. Out of respect, and with a willingness to receive the trees’ offering, we reached out to the local community for knowledge of how to process, store, and prepare food from the nuts. At first, most of the responses we got from neighbors and old-timers regarding the use of acorn ended in comments like, “It’s too darn much work!” or “They’re just too bitter!” Luckily, an experienced neighbor provided the inspiration and support we needed to get started.
Collecting and cracking
With two pairs of hands, we were able to collect 50-60 lbs. of acorns in an hour just by picking them up from beneath the trees. We dumped the acorns into a large container filled with water?good ones sink, bad ones float. Next, we poured the acorns onto a large wooden board. Using a rock pestle we found here many years ago, we cracked as many as we were ready to use. Removing the hard shell, we set aside less desirable pieces for our chickens. One might want to cover the acorns with an old towel or cloth while cracking them to keep the pieces from scattering. Another possibility is to put handfuls of acorn on a solid piece of wood on the ground, cover them with a cloth, and then crack the nuts open with a square-bottomed soil tamper. We’ll try this technique to speed up the process in the fall. A hand-cranked nutcracker reportedly works quite well for acorns. (8)
After shelling the acorns, they must be leached to remove bitter tannins. (9) To do this, we grind the acorns roughly in a blender, then put the chopped nutmeats into 1/2-gal. jars fitted with screened (sprouting) lids. We cover the nuts with cool water and keep them in a refrigerator (or outside, during cold weather). We change the water and rinse a couple of times a day for 5-6 days. As part of this process, we skim off any floating acorn skins. When the acorn meal is no longer bitter to taste (5-6 days), we dry it for storage. Any remaining acorn skins can be winnowed when the acorn has been dried.
Bitterness can be removed more quickly by pouring boiling water over the acorn meal a few times, but this tends to change the color of the meal and may decrease its nutritional value. We prefer the cold-water method. Others have leached acorn meal by placing crushed acorn in a mesh or burlap bag and submerging the bag in a clean stream of moving water for some days to remove the tannins. One of our batches was finely ground in a hand mill after chopping and drying, and then placed in a fine mesh bag used for making nut-milk and set outside in a basin of water. It froze and thawed a few times in the cold weather. When we rinsed the meal, it was the least bitter we had processed for the least amount of effort. Grinding the acorn more finely increased the surface area for leaching; the freeze-thaw process further broke down the cell walls. We’ll experiment more with this technique.
Storage and use
After the tannins have been removed, acorn meal can be dried and stored in the refrigerator, freezer, or potentially outside if the weather stays cold enough during the winter. Uncracked acorns can be stored up to a year (native tribes stored them for two years or more). Be sure to do the float/sink test and cull any rotten or wormy ones. Then dry the unshelled acorns and store in a rodent-proof bin in a cool, dark place. They can be processed as needed. Acorns can also be sprouted before processing. As with other nuts and seeds, their nutritional value increases with germination.
Acorn meal just feels right to eat. Last fall, I found myself snacking on tablespoons of raw acorn meal as I went about my fall chores. When we are ready to use our acorn, we put the roughly ground chunks through a hand-cranked grain mill, turning it into a meal or fine powder which can be incorporated into soups, breads, and breakfast cereals. Recipes abound for the use of acorn. It can also substitute partly or wholly for corn flour in recipes that call for that.
Our chickens eat the nut meats after the shells have been cracked. We keep a covered container of acorns near our flock. When needed, we place a handful into a bucket and then use the blunt end of a cut fir pole to crush them before throwing the pieces out to the fowl. Their willingness to consume the acorn increases after the tannins have been removed, but we save the majority of processed acorn for ourselves.
Acorns can be fed to pigs and other livestock as a supplementary grain. They are a favorite food of deer, black bear, squirrels, some birds, and rodents. We pick up only what we are able to use and leave the rest for the non-human residents of the land.
Grandmother white oak (Quercus garryana) provides food, shelter, shade, and beauty. Photo by Kaliana Keegan.
A long-lasting perennial polyculture
In permaculture, we create guilds of plants that are mutually beneficial in order to increase the sum of all yields, and to minimize labor and external inputs. We understand that, in our designed systems, resiliency is dependent upon diversity. The synergy between interdependent parts forms strong bonds that can survive and adapt to changing conditions. A mature oak woodland embodies the essence of our most demanding design criteria?a resilient and long-lasting foundation of complexity, reinforced by the species it supports and is supported by.
Foraging in filtered light under the canopy of black oak (Q. kellogii) and Oregon white oak (Q. garryana), a diverse polyculture unfolds, revealing foods such as miner’s lettuce (Claytonia perfoliata), chanterelles (Cantharellus cibarius), black trumpets (Craterellus cornucopioides), serviceberry (Amelanchier spp.), wild strawberry (Fragaria vesca), numerous edible species of geophytes (perennial tubers, corms, and bulbs), and licorice fern (Polypodium glycyrrhiza), an edible epiphyte that grows on the mossy trunks of shady oaks. Along the woodland edges and in sunny openings, we have collected wild rose hips (Rosa californica), gooseberries (Ribes spp.), and blackcap raspberries (Rubus leucodermis). If one choses, there are California quail, mule deer, and wild turkey.
Here on the North Coast, a tan oak (Notholithocarpus densiflorus) polyculture can yield huckleberry (Vaccinium ovatum), thimbleberry (Rubus parviflorus), chanterelles, boletes (Boletus spp.), oyster mushrooms (Pleurotus ostreatus), Oregon grape (Mahonia spp.), redwood sorrel (Oxalis spp.), and hazelnut (Corylus cornuta) just to mention a few choice foods. During days of wild-food gathering, we are often serenaded by neotropical and resident songbirds overhead. As they forage on the abundance of insect biomass, their fertile guanos fall to the forest floor in return.
A reintegration revival
Ecologists use the term trophic cascade to explain the negative consequences of changes that stem from often misunderstood linkages among various species within a food web. In a top-down induced trophic cascade, the removal of a key predator from an upper trophic level (wolf, grizzly bear, cougar) may set off a cascade of events that later reveals interdependent bonds intrinsic to the ecosystem. Species in lower feeding levels that once appeared to be disconnected from the larger predators are shown to be quite dependent. One such example is the extermination of the wolf in Yellowstone National Park. This was followed by the strange disappearance of songbirds and beaver in the park’s valleys. Biologists were stumped by the troubling phenomenon until wolves were reintroduced, after which the birds and beaver returned. An over-simplified explanation is as follows: no wolves = lazy elk = overgrazing of riparian habitat in valleys = no willows = no birds and beaver = overall decline in ecosystem health and vibrancy.
Here in California and across the entire continent, we are experiencing symptoms of a multitude of trophic cascades that have reduced the carrying capacity of entire landscapes. Perhaps as important as the loss of key predators is the loss of the human connection to the landscape. The removal of humans from direct participation in the natural order has resulted in a profound trophic cascade.
The forced removal of indigenous peoples from their native lands has disrupted and displaced over 10,000 years of embedded knowledge and connection to place. This loss, coupled with modern society’s belief that “nature” is best left alone, has caused the separation-induced stagnancy of many of our ecosystems, complicated and diverse natural communities that have co-evolved with the careful tending, harvest, and propagation practiced by deeply connected human hands.
The oak woodlands, savannas, and chaparral have grown lonely, and we will have to overcome our separation consciousness with a reintegration revival! As students of permaculture, we should seek not only to design food forest, kitchen gardens, and animal-forage systems close to home, but also dare to venture into what we have come to mistakenly call "wilderness" to find our place as an integral part of natural systems. In order to accomplish this, we will need to seek out the traditional ecological knowledge of the native people who once tended the land. It will take a commitment to staying in the place we choose to sink our roots. The transient nature of our culture continues to sever the land-human connection, a bond that depends on prolonged observation and knowledge passed on by the people of that particular place. In Gary Snyder's words, "Find your place on the planet, dig in, and take responsibility from there."
Recovering and protecting oak woodlands
An acorn falling from the boughs of an ancient mother oak comes to rest on a very different landscape than it would have centuries ago. The perennial bunchgrasses that once carpeted the earth beneath the oak canopy have been replaced by the annual grasses introduced from other lands. The park-like feeling described by early explorers who walked into oak woodlands kept clear for thousands of years by indigenous burning is being lost. The woodlands are now being invaded by the succession of Douglas fir (Pseudotsuga menziesii). The loss of large predators such as the mountain lion and grizzly bear has altered the ability of woodland ecosystems to regenerate due to the unchecked proliferation of browsing deer. In California, large areas of oak woodland have been converted to monocultures for the fast-growing wine industry. The introduced pathogen (Phytopthora ramorum), otherwise known as Sudden Oak Death, has devastated entire oak forests, altering species composition on tens of thousands of acres of once plentiful oak-dominated polycultures. (10)
The health and resilience of oak-woodland ecosystems are closely connected with the co-evolutionary presence of low-intensity fires. Of all the negative forces contributing to the conversion of oak woodlands, the ongoing suppression of fire may pose the most serious threat to their long-term survival.
The health of human cultures and oak-woodland ecosystems requires a reciprocal act of reconnecting. Perhaps we should view "wildlands" more as "cultural landscapes," places where we can learn to tell a new story of now that begins as we re-enter our food webs responsible. As we design more productive and accountable food-production models, those of us fortunate enough to live in acorn territory must not forget the potential of the life-giving oak.
Kyle Keegan lives off-grid with his life partner and daughter on a remote property in Humboldt County, California. A life-long student and teacher of ecology and nature awareness, he trained in permaculture at Occidental Arts and Ecology Center in 2008. Kyle is a market gardener, seed saver, nature historian and stream and upland restorationist, who savors community organizing and ritual. He credits Dennis Martinez, ethnobotanist and restorationist, and Brock Dolman for many stimulating discussions of eco-restoration and California landscape. Contact Kyle at owlsperch[at]asis.com or PO Box 565, Miranda, CA 95553
1. Bainbridge, David A. 1986. Use of Acorns for Food: Past, Present, Future, presented at the Symposium on Multiple-use Management of California's Hardwoods, Nov. 12-14, 1986, San Luis Obispo, California. Available online at www.ecocomposite.org/native/UseOfAcornsForFoodInCalifornia.doc
2. Pavlik, Bruce M., P. Muick, and S. Johnson. 1993 Oaks of California, Los Olivos, CA
3. Bainbridge, loc. cit.
4. Anderson, M. Kat. 2005 Tending the Wild: Native American Knowledge and the Management of California's Natural Resources, University of California Press, berkeley, CA
5. Biswell, Harold. 1989. Prescribed Burning in California Wildlands Vegetation Management, California Press, Berkeley, CA.
6. Bakker, Elna. 1984. An Island Called California: An Ecological Introduction to Its Natural Communities, California Press, Berkeley, CA.
7. Bainbridge, loc. cit.
8. Davebilt Co., Lakeport, CA, www.davebilt.com 707-263-5270
9. Ocean, Suellen. 1993. Acorns and Eat 'Em: A How-To Vegetarian Cookbook, Complete Directions for Harvesting, Preparing, Cooking Acorns. www.californiaoaks.org/ExtAssets/acorns_and_eatem.pdf