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Constance Bay Red Oak Acorn Oil Experiment: Progress to Winter Solstice 2008

By the time well over 90% of the acorns had already been collected, the leaves began to fall, hiding the last ot the crop. This last 10% is the best of the crop, so collecting methods that can economically reveal these acorns for easy collecting might well be worth the effort.

The acorn crop collecting method for the experiment was largely be hand - reach down and pick up. This method would be fun for kids but it is wearing for adults, who stand too far above the ground. Two kinds of manual collectors were tried out as well. These are cane-like, their handles spanning the distance to the ground, with wire basketry on the business end. These were quite helpful in relieving the strain but did not speed collecting by much. Other devices are made and could be tried in future years.

The background metaresearch for the experiment also revealed other opportunities for red oak acorn use, besides the oil. Leaching toxic tannins from these acorns (a prerequisite to their food uses) produces a liquid said to be an effective insecticide against garden pests. The acorn shell is a good mulch for indoor and outdoor plants, or as compost candidate. The acorn kernel can be ground as a nut meal (used like cornmeal), can be used to make a nut milk the residue of which is often called acorn starch or flour which in turn can be used to make a tofu-analog jelly or used in various baked goods. The overall nutrition offered by the the acorn is high, possibly the best of any nut. Note: wine can be made from oak leaves, and ink from galls.

Samples of acorns have been processed to the leaching stage. The first step is to open the nut. Our acorn shells are not brittle like other nuts, but softer and somewhat leathery. So, we began cutting them in half. Using nut picks, we pulled the kernel with its pellicle cover, out the half shell. By boiling these kernels, we were able to towel off the pellicle (we removed the pellicles because it is said to be high in tannin - however, the boiling may remove this tannin, so the pellicle could stay as is often done with almonds and hazels.) We also simply boiled the halves directly. This made extracting the kernel and removing the pellicle still easier. So, now we are at the stage of removing the tannins from the kernel. A coarse grinding followed by a boiling in several water is supposed to do this job. We are using a 40-coffee urn to do this. The coarse meal is put in the basket. The filled urn is set to percolate. After the urn completes the percolation, the tannin water is drained and stored. Fresh water is added and percolation repeated. After several repetitions, the water should becoming out clear and tannin free. The acorn meal is ready for use, it soil still in tact.
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By the end of the season we had gathered almost 100 kg of acorns from six trees. We did not gather all the acorns these trees produced, and maybe not even half. With better gathering methods, we could get almost in the four weeks or so that the better acorns were falling. However, as you can see we got our 'three bags full'. Bag storage is probably OK once the acorns have been sufficiently dried, but having stacking bread crates (which we did not have, yet) would be much better for the drying process. We noticed that the acorns in the centre of the bags got mould on the outside of the shell. We do not yet know if these kernels are damaged.
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About a third or so of the acorns that passed the float test (they sank) turned out later to contain curculio larvae, as showed in this picture. The larvae usually ride the acorn to the gorund, then cut a small exit hole in the shell and escape into the ground to overwinter. Acorns foud with small holes have had the larvae inside all season (the eggs are laid in the young acorns in the spring. The red oak group take two years to mature their acorns, whereas the white oak group completes the job in one growing season (the red oak acorns also winter over before germinating the next spring whereas the white oak group acorns germinate as they fall.)
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Here we see a sampling of the acorns gathered in 2008. They vary in size by about a factor two and in shape from almost round to long and bullet shaped, being almost twice a long and wide. Each tree produces acorns of a particular shape and size. If it proved that different trees acorns also varied in flavour, this feature could be taken advantage of in future harvests and future plantings of replacement trees. Besides the red oak growing well in the soils of the Bay, american sweet chestnut (newly emerging from its hundred year cankered dystopia as a cnaker resist species, is ready for planting around the Bay). Also, the korean nut pine, the asian analog of our own eastern white pine (which grows hereabouts) could make and appearance on our pennisula.
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Here we see red oak kernel ready for grinding into meal. The acorns were cut in half using the Cobjon Universal Kernel Extractor. These halves were then put into boiling water for a few minutes, until the kernel was falling out of the shell. There they were taken a few a time out of the hot water and into a towel which rubbed off the brown pellicle ( the seed coat). These kernels still have their oil. They should be roasted then ground into meal. If the oil is to be extracted, then the meal can be put into a large pot with much water. As the water is boiled, the tannin (water soluble) is extracted into the water. As the tannin is not oil soluble, the escaping oil is not contaminated. The oil floats to the surface where it can be skimmed. The tannin water can be saved for garden use and the solid residue dried into acorn flour, aka starch.
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Canada Nutculture Association, Ottawa, Canada: "Progress through Research & Development"