Do you know why you can’t get cashews in the shell. I had no idea. Actually, I never thought about it. But, come to think of it, you can get almonds, walnuts, pistachios, brazil nuts, hazelnuts, peanuts, chestnuts, pine nuts, pecans, and even macadamia nuts in a shell, but not cashews.
Why? It turns out that the cashew shell is toxic. However, that raised the question of what a cashew looks like in its shell. Again, I had no idea. When I found out, I knew more people should see it. It is weird looking, and very caustic, too!
Cashews, like many of the culinary nuts listed above, are not true nuts in the botanical sense. True nuts develop a hard wall around the seed (e.g. hazelnuts). Cashews instead have a lining around the seed that is filled with a nasty fluid.
Cashews are in the same family (Anacardiaceae) as mangoes, pistachios, sumac, and poison-ivy. Many plants in this family produce Urushiol, an oil that can cause a nasty, painful rash. (a friend of mine had not been told about this when he came across them in Brazil, and burned his mouth on a fresh cashew. Ouch. He also took some pictures of the local “caju” fruit.) The cashew stores this icky stuff in the lining around the seed, which makes cashews very difficult to process. They are usually roasted to release the fluid, which is collected for other uses, such as Varnish. After that, the hardened lining must be removed by hand.
That’s pretty weird, but it gets weirder. In the cashew, the ovary develops outside of the fruit, which really makes it a false fruit, since by definition fruits have seeds inside. The false fruit attached to the false nut looks like a pear with a little boxing glove hanging off the bottom. When ripe, the whole thing falls off the tree, and the bottom part is gathered for processing.
The false fruit (called cashew fruit or cashew apple) is edible, but it is very perishable. It is often left to rot, but can be eaten raw, cooked, or used to make a liquor called feni. While the fruit and its juice are available in parts of the world where cashews grow, they are apparently too perishable to appear in stores in the US.
I am MAD
