Acorn: The Perennial Grain
Kym Kemp / Friday, Nov. 23, 2012 @ 10 a.m. / Environment
Photos in this article provided by Kyle Keegan
The following piece is a guest article by Kyle Keegan. It was first printed in Permaculture Magazine and was adapted to fit a broader audience here.
Oaks, of the genus “Quercus” are widely distributed over many of the temperate parts of Europe, Asia, North Africa and North America. Their edible nuts (acorns) were a reliable staple food for 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 U.S.
Growing staple crops on marginal land has been an age old struggle. Carbohydrates, the source of metabolic energy, drive many of life’s processes, and are a basis for survival. However, most agricultural practices that rely on annual plants (grains, legumes vegetables), 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. Interestingly, some evidence suggests that annual-based 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 design model for a perennial polyculture in temperate North America.
Unlike corn, barley, wheat, or rice; acorn requires no tilling of the soil, and neither fertilizer inputs nor irrigation. Acorns are relatively simple to collect, store and process and 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 on 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 woodlands have been recorded to yield up to 6,000 lbs of acorn per acre.3 Sadly, the current health of most oak woodland ecosystems is compromised due to the loss or lack of indigenous management practices (including prescribed burning). As a consequence, acorn production has declined, and crop yields have become more inconsistent.4,5,6
Acorn was a staple crop 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 time is probably less than that of a cereal crop, while the nutritional value of acorn compares favorably with wheat or barley. The quality and flavor of acorn oil is reportedly similar to olive oil,7 and the residual nut meal can be used as animal fodder after the acorns have been pressed.
What Were We Thinking?
Thirteen years after moving to 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!
This past fall, thousands of Tan Oak (Notholithocarpus densiflorus) acorns fell on our driveway, right outside of our home. Out of respect, and with a willingness to receive the trees’ offering, we reached out to the local community for knowledge on how to process, store, and prepare acorn. 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 labor intensive!” or “They’re just too bitter!” Luckily, a close 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 by picking them up from beneath the trees. We then dumped the acorns into a large container filled with water, (good ones sink, bad ones float). Next, we poured off the water and placed the acorns onto a large wooden board. Using a rock pestle we had found here many years ago, we cracked as many as we were able 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 next fall. A hand-cranked nutcracker reportedly works quite well for acorns.8
After shelling the acorns, they must be leached to remove bitter tannins. 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 then change the water and rinse a couple of times a day for 5-7 days. As part of this process, we skim off any floating acorn skins. When the acorn meal is no longer bitter to tast