Processing Cashews for Edibility

There is a reason why you cannot buy cashews in the shell. Cashews are poisonous if they aren’t processed properly. That’s no big surprise considering they are in the same family as poison ivy. In fact, its toxin, urushiol, is the same allergen that gives poison ivy its itch.

Illustration from "Dictionnaire Pittoresque d'Histoire Naturelle et des Phénomènes de la Nature"
Illustration from “Dictionnaire Pittoresque d’Histoire Naturelle et des Phénomènes de la Nature”

Cashews are grow as a hanging nut underneath a false fruit (false fruit having their seeds on the outside) sometimes referred to as “apples”. These apples grow in trees that can reach around 30 feet tall.

First image of a cashew tree (drawn by French explorer André Thevet)
First image of a cashew tree (drawn by French explorer André Thevet)

After being picked, the cashews are roasted to release the poisonous fluid. This leaves a wrinkled and dried skin on the cashew which is then removed.

Cashews ready to be peeled
Cashews ready to be peeled

The “cashew nutshell liquid” is sometimes collected and used in things like varnish and even fungicides.

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