Acorns are nuts from oak trees.
There are really, from a food aspect, two types of acorns: Spanish and North African acorns, and all the rest.
The acorns most worth bothering with are considered to be those of the oak tree known variously as holly, holm or ilex oak (Quercus ilex var rotundifolia -- aka var ballota) which grows all around the Mediterranean, including particularly north-west Africa, Spain and Portugal. These are long, cylindrical acorns. When fine Spanish ham makers boast about their pigs being allowed to eat acorns, you may have wondered why eating those bitter old things would improve the taste of their meat. It is in fact these nuts, which the Spanish call "ballotas", that the pigs eat. In some parts of Europe, pigs still allowed to room the woods and eat these acorns; a pig will eat 22 to 26 pounds (10 to 12 kg) of the nuts a day.
These trees are even cultivated for their acorns, and some think them as good as chestnuts. These would have been the ones that a Duchess (in Don Quixote) would have bothered asking for. They can be eaten out of hand like nuts (once shelled, of course.) In Spain, the acorn season is called "montanera."
These acorns are also used in Morocco for making flour and oil from.
Acorns everywhere else in the world are bitter to a greater or less extent owing to tannins in them. They have to be "processed" first before they can be eaten by humans through a leaching process.
To do this, shell the acorns first, but leave them whole. Boil in water, but as soon as the water turns a light yellowy brown, replace the water with fresh water and start the boiling process over again. Repeat this process for about 2 hours or until the water stays clear. Some people advise to soak for several days in water, changing the water frequently, and then boil. They turn dark brown after the boiling. Alternatively, tie them up in a piece of cheesecloth or in a nylon stocking, and hang them inside the toilet tank (nb: tank, not bowl.) The tannins leak out into the water, and the water gets changed everytime someone flushes. This, however, can discolour your toilet bowl, and may make the Acorns sound even less appealing to your guests when you tell you how you prepared their meal. You need to leave them in the tank for about 4 days.
After processing, roast the Acorns in a 350 F / 180 C oven for an hour.
At this point, you can start to use them, but before you do, do a taste test to make sure all the bitterness has gone before you start cooking with them.
If all this sounds like a lot of work, remember tapioca is also a lot of work; we just never have to do it. And it's the same with olives: they have to go through a similar leaching process to get the bitterness out to make them edible, Some have tried curing acorns as you would olives, in brine or in lye, but acorns have not responded well to the treatment, either in terms of taste, texture or appearance.
Given all the work, though, some say the taste at the end with this kind of acorns just isn't worth the effort.
There are two main types of oaks in North America:
- Red oaks: pointy points, dark-coloured, deeply ridged-bark;
- White oaks: rounded points, greyish-brown bark, more scaly.
Some people say that acorns from white oaks can be used without the water processing first, because they are less bitter than acorns from red oaks. Others say that they though acorns from white oaks are less bitter, they are still best water processed first.
Some of the better tasting North American acorns are from these trees in the white oak family:
- California Live Oak (aka Quercus agrifolia Nee, not the same as Interior or Virginia Live Oak, aka Quercus virginiana.) Has long, skinny acorns.;
- Burr Oak;
- Chestnut Oak (sic);
- Oregon White Oak (aka White Oak, Post Oak, Brewer Oak, Quercus garryana.)
In Japan, the oak tree that produces the best acorns for eating is called "Matebashii" (Pasania edulis.) The leaves of the tree, which are evergreen, don't look anything like a North American or a European would think of as an oak leaf, though. In fact, it's no longer classified scientifically as an oak, and is also called a "Japanese False Oak."
In China, acorns are eaten from the oak species whose scientific name is "Quercus cornea."
The protein in ranges from 2.3 - 8.6 % of weight. Compare with wheat, at around 11 1/2 % of weight.
Indians in North America used acorns as a food. Some tribes leached them in running streams.
They tell me there are big acorns in your village; send me a couple of dozen or so, and I shall value them greatly as coming from your hand; and write to me at length to assure me of your health and well-being; and if there be anything you stand in need of, it is but to open your mouth, and that shall be the measure; and so God keep you. From this place, Your loving friend, THE DUCHESS."
Literature & Lore
-- Miguel de Cervantes. Don Quixote, Chapter 50.
A person who eats acorns is a "balanophagist."