Since I first got interested in native edible plants, I had heard about the edibility of oak acorns. I read in many books and articles in mainstream publications and heard personal accounts that acorns can be processed to make flour to replace or mix with wheat flour, or to be used in desserts for their nutty flavor.
However, I always hesitated to go through the process myself because I also heard a lot of complaints about the process being too cumbersome and not worth the time, the flavor being too bland and other negative comments.
It wasn't until I went to the Midwest Wild Harvest Festival at the end of September in Prairie Du Chien, Wisconsin, that I decided to try it for myself. I tasted some delicious desserts and savory dishes with acorn flour. One of my favorites was a persimmon cake prepared with acorn flour.
My friend Jen Sieradzki, who works at the Shaw Nature Reserve, recently offered a class about Wild Native Edibles, and she told me she prepared acorn burgers for participants. She said "they turned out really good and were the stars of the show."
The event and Jen inspired me to experiment on my own. I started collecting acorns from our pin oak tree, however, they have lots of tannins and are very tiny. Then I remembered there is a bur oak tree in our neighborhood that is very productive. I have collected those acorns in the past few years to make tree ornaments, specifically owls sitting on a nest (acorn cup). This year, acorn production has been even better, and there were so many that they did not seem to be consumed by squirrels or other animals. Black walnuts are so abundant and squirrels seem to be having plenty of food.
Nineteen species of oaks (Quercus sp.) are native to Missouri and are divided in two groups: the white oaks and the red (or black) oaks.
The leaves of white oaks are lobed, the lobes and ends of the leaves are rounded and smooth. The leaves of red oaks are lobed or entire and have bristles at the end of the lobes or leaves. Oak trees are the most important trees in Missouri. They are dominant species in woodlands, forests and savannas. Their acorns are important food for mammals, birds and insects and even for domestic pigs. For more information on oaks check the article "Missouri oaks" on the Missouri Department of Conservation website. A good source of native oak trees in Missouri is Forrest Keeling nursery in Elsberry and can also be ordered from the MDC George White nursery.
All acorns have tannins making them bitter but acorns from white oaks have less. Tannins need to be removed to make them palatable for humans. This can be achieved by leaching the acorns with cold or hot water.
If acorn flour is the final product, leaching should be done with cold water. According to the U.S. Department of Agriculture, acorns contain carbohydrates, fats, proteins and minerals like many other nuts. Acorns were staple food for many Native American tribes and some Native Americans in California still consume them regularly.
As for almost every native edible plant I write about, there are always reports of toxicity in some cases. After leaching, acorns are edible for humans; however, because horses and cattle consume the acorns outdoors (if they eat too many) the tannins can be toxic, especially during dry periods when no other forage is available. There are some reports that they may even die. Wild animals, however, are not known to be killed by acorns.
After reviewing a few references, including "Edible Wild Plants" by Thomas Elias, Peter Dykeman's "Adventures in Edible Plant Foraging" by Karen Monger, 'Backyard Foraging' by Ellen Zachos and several others, my husband Randy and I were ready for our first test.
Acorns should be collected as soon as they fall from the trees and stored in a cool place if they are not processed immediately. Acorns can be infested by weevils and beetles, so some may be damaged. Discard or compost those and select the ones that look clean.
To process, remove the acorn caps (fused bracts), crack the nuts open and discard the acorn shell (pericarp). Remove the seed coat or skin. If the seed skin is hard to remove, heat the acorns in an oven for 3-5 minutes at the lowest heat or use the pilot light for 2-3 hours or until the skins detached themselves from the acorns and are easily removed.
Coarsely chop the acorns by hand or with a food processor and proceed to leach them in a container with cold water. Change the water daily for several days until the water is clear.
Initially the water will be light brown. Depending on your acorns, this may take you five days to two weeks. It took us only five days to leach our bur oak acorns, which are in the white oak group. After leaching, Randy chopped the acorns again in a food processor, but this time more finely until getting a corn meal-like texture. Then we placed the meal on trays lined with wax or parchment paper. We dried ours in our oven overnight by the heat of the oven light bulb only.
Store your dry "acorn meal" in containers in the freezer to protect from deterioration.
This may sound like a lot of work, but the truth is we didn't spend much time in each step. It takes a few days but it is not difficult to do, and it is fun to eat something so abundant and easily found in our state.
You can find a number of recipes in books and websites, and here I am providing my own recipe. This is traditional bread prepared in my native El Salvador, it is called quesadilla, but it is a sweet bread not a savory dish like the Mexican quesadilla. Both have cheese, or "queso" in Spanish, as one of the main ingredients.
Dr. Nadia Navarrete-Tindall is a native plant educator and independent consultant. She offers educational workshops about native edible plants and other topics on native plants, as well as consultation on native plants for yards and acreages. She lives in Columbia, Missouri, with her husband Randy and their dog Bonita. She can be reached by email at [email protected] or on her Facebook page at "Native Plants and More." Stay tuned about our own Wild Harvest festival(s) in central Missouri in 2018.