Acorns as Food and Flour. How to Gather, Prepare and Enjoy| Updated: May 11, 2019
If you are like most people and didn’t know that you could eat acorns and even bake delicious goodies with acorn flour, read on to find out more!
Acorns: North American Superfood
The oak tree is an important part of ecosystems and economics. The wood from oak trees has heated homes, built ships that crossed the oceans, and supported buildings that touch the sky. These stately trees provide food and habitat for countless animal species and shade for more delicate plant life.
Oak leaves are an important herb for cooking. For example, a few freshly picked oak leaves keep fermented pickles crunchy!
As Autumn approaches, nut mast, produced by the decomposition of nuts on the forest floor (think of it as a semi-fermented, preserved nut paste!) provides food through early winter for numerous animals, especially pigs. Acorns contribute incredible amounts to this food source.
Imagine eating a thousand pounds of something per year, say roughly two and a half pounds of potatoes per day. It seems impossible, right? But estimates and research shows that some traditional groups in North America ate this much acorn annually. (1)
Acorns weren’t just prized for their food. The nuts were often crushed and boiled to create an oil that natives used for many purposes, including cooking and as medicine. The oil was an important component of many herbal salves used to treat wounds and burns.
A large number of tannins in acorns came in handy for tanning hides as well. Tannins bind to the collagen in the hide and coats them, creating a waterproofing effect that is more resistant to molding and other types of microbial degradation.
Benefits of Eating Acorns
Have you noticed that there are LOTS of acorns around? Perhaps you never even realized that you could eat them!
In many areas, no one bothers to collect almost any of the acorns available. In just a half hour or so work, you can harvest many, many pounds of acorns for use in your home.
If you have oak trees of your own or access to such trees, you can simplify collection even further by spreading a tarp, blanket or similar fabric beneath the tree to allow the acorns to fall right into it. So, while commercial acorn flour and foods made with it are expensive, preparing them yourself is very cost effective. In many cases, it’s free!
Compared with industrialized alternatives, acorns are an environmental win. This holds true even against organic grains and cereals. First and foremost, consider that oak trees are incredibly productive. In an average year, mature trees may drop 200 or more pounds of acorns. In ideal years, some reports clock a single tree at a thousand pounds! (2)
Because they can live for many decades – even centuries – and don’t need replanting every year like other crops, oaks can provide a nearly endless and valuable source of food for people, livestock and wildlife.
Free Food with No Machinery or Chemicals
An acre of oak trees can produce many tons of food with no machinery or inputs for dozens of years. It is no surprise that acorns are sometimes referred to as “the grain that grows on trees.”
This incredible productivity doesn’t include all the wildlife that such an ecosystem would support. Deer, elk, pigs, and other animal species can thrive on this abundant and nutrient dense food source, widening the amount of food available in a given area for low to no additional cost for its human caretakers.
As a perennial tree crop, acorns can be grown year after year without cultivation, fertilization, irrigation, or — in most cases — spraying for pests. The oak also has the ability to yield well on marginal land, including steep, erosion-prone hillsides. Acorn production has other benefits, as well. The trees contribute to soil deposition, provide increased rainfall retention for replenishing the groundwater supply, act as windbreaks, supply summer shade, furnish harvests of hardwood lumber and firewood, and in the case of one oak (Quercus suber), cork. What’s more, the tannin present in many acorn varieties is a sought-after commercial product. (3)
Gluten Free Acorns
Used as an alternative grain, acorns are gluten-free. In addition, because oaks are rarely sprayed and seem to thrive with little intervention, the use of acorns and acorn flour for food is free of the drawbacks of other types of gluten-free flour options.
Rice and rice flour is an arsenic risk, for example. Other gluten-free crops such as oats and corn are typically grown with glyphosate, with post-cultivation tests revealing high levels of this chemical.
Other nut options like almond flour are very expensive even if you make it yourself.
Hence, acorns are a clean, green option without the drawbacks either chemically or economically of cultivated competitors.
Acorn Nutritional Information
Nutritionally, acorns are pretty outstanding. No wonder some Native American groups ate so much of them!
The fat from acorns is primarily monounsaturated – the kind found in olive oil and avocado oil. They are relatively low (for a nut) in polyunsaturated fatty acids at around 35%. Saturated fat is around 13%. (2)
For a plant food, acorns offer an excellent protein profile, containing all the essential amino acids, although not in sufficient amounts to stand alone as a single protein source for humans.
They are a rich source of the minerals potassium and manganese along with providing a modest contribution to a wide range of B-vitamins.
The macronutrient profile of acorns is as follows. Note that while being high in carbs, the generous amounts of monounsaturated fat give acorns a low glycemic index overall. (3)
- 45% carbs
- 50% fat
- 5% protein
Because there are so many species of oak trees scattered across the world, the composition of various acorns will vary both from species to species, and location to location. Some acorns are sweeter, some more bitter.
Chances are that there are numerous types of acorns in your community that you can try and see which ones have the most appealing flavor. Acorns from bur oaks that grow in eastern and central North America generally seem to be tastier than others, but all are edible!
Proper Acorn Preparation
Acorns are not, at least for humans, a “ready to eat food.”
In other words, you can’t just gather them up, wash them and start eating.
Like many nuts, they require special care to prepare. Traditionally, they are soaked for long periods of time to remove the bitter tannins and other anti-nutrients they contain.
The water created from soaking acorns is thus high in tannins. The resulting dark brown liquid has a number of possible uses, such as the natural tanning of animal hides mentioned above.
One reason animals let the acorns sit on the forest floor for weeks before they finally eat them is to let nature wash out some of the tannins and other toxic compounds. I wonder if people first thought to rinse and soak nuts, seeds, grains, and other plant foods by observing this very traditional and natural process at play around them?
The process of soaking acorns is often called “leaching.” The process deals with the two big anti-nutrients in these nuts – phytic acid and tannins.
While the phytic acid usually isn’t noticed until it hits the digestive tract, blocking absorption of minerals and possibly inflaming the tissues (gas or bloating can result), tannins are noticed immediately in the mouth. Nibble on a raw acorn and you will immediately see what I mean! More than likely, you will spit it right out!
Tasting bitter and astringent, tannins also bind with minerals and block use by the body. Careful leaching with water easily deals with both of these powerful substances. (4)
Soak and then Rinse
Leaching involves soaking the acorns in water then rinsing them. Traditionally, people had a wide range of approaches to processing and storing acorns, based on the variety and final intended use. Two methods today mimic these practices – hot or cold leaching.
The benefit of hot leaching is speed. It takes just a few hours to complete. The process is similar to boiling peanuts.
The drawback? The final flour is very dark and the process destroys a beneficial starch in the acorns that act similar to gluten in regular grains but doesn’t generate the same allergic reactions. This starch is helpful as a binder when baking with acorn flour is the goal. (5)
Traditionally, cold leaching was the preferred method for home processing of acorns. While much slower, it preserves enzymes and some nutrients by maintaining the rawness of the acorns. The important binding starch in acorns is preserved also. Thus, this method is preferred when making acorn flour.
Cold leaching can take up to a week but produces a superior final product. It involves shucking then soaking the acorns in cold water, with a daily changing or straining of the liquid. While the phytic acid is removed quickly within hours of soaking, the tannins take longer. Once the soaking water no longer turns brown, you know the bitter tannins are gone!
After leaching, acorns must be thoroughly dried. A food dehydrator or the pilot light in a gas oven works very well. If you live in a warm location, drying in the hot sun works too. If not dried, the wet acorns will rapidly mold.
Dried acorn nuts are best stored in an airtight container in the refrigerator or a cool, dark pantry.
How to Bake with Acorn Flour
Before making acorn flour from the dried nuts, definitely check out a few good tutorials on the different approaches first! While it isn’t hard, it takes a bit more care than preparing more standard grains.
Acorn flour behaves very differently than most common wheat varieties and related flours like einkorn. It makes a great flour for breading foods that will be fried or baked. Looking for a healthy gluten-free flour to bread pork chops or similar cuts of meat that is locally sourced? Try acorn flour!
Acorn mash, acorn bread, acorn waffles, pancakes, and muffins! The sky’s the limit with what you can make from acorn flour, either alone or combined with other ingredients.
Foraging for Acorns Sustainably and Responsibly
One important part of eating wild foods is learning to harvest them in a way that doesn’t harm the plant or the ecosystem and other creatures that depend on those plants. Oak trees vary greatly from year to year when it comes to productivity. “Mast” years, when the trees drop incredible amounts of nuts, are very important for the future of the oak stands – the extra nuts often get buried by squirrels and other critters to emerge later as baby oak trees!
In lean years, it is especially important to go light on your harvesting. I find the rule of three helpful – never take more than one-third of the available foraged food. Also, never forage in an area that shows signs of another person already having foraged there.
John Moody is an author, speaker, farmer, homesteader, and Real Food activist. Most importantly, he is husband to an amazing wife and five awesome kids. John speaks nationally at a wide range of events, along with writing for numerous publications and consulting for farmers, homesteaders, and food businesses.
He recently published his first book, The Frugal Homesteader: Living the Good Life on Less.