A native of Brazil the cashew tree was brought to India in the sixteenth century by Portuguese traders. The actual cashew nut or seed is inside a kidney shaped shell that is attached to the bottom of the edible cashew apple. Delicately sweet and somewhat buttery in flavor, cashews are used in cuisines world wide.
The cashew tree (Anacardium occidentale) is evergreen and thrives in tropical regions. It is in the same family as both mango and pistachio trees, It grows to around thirty to forty feet in height and prefers well drained soils. One of the reasons Portuguese traders introduced cashews to coastal India and Mozambique was to prevent erosion of the sandy soils. The English word cashew comes from the Portuguese word caju which is derived from Brazilian indigenous peoples' name for the seed acajú, literally meaning "nut that produces itself."
Cashew trees flower and set fruit during the dry winter season in tropical climes. The flowers are produced in a panicle up to ten inches long. Each flower pale green at first, turning reddish or pink upon opening.
The part we know as the cashew nut forms first as it is the seed. The cashew apple is not a part of the plant ovary like most fruits and is actually just the swollen stem of the fruit.
The pulp of the cashew apple can be eaten fresh, canned in jams or chutneys, or used for juice. The sugary juice can be fermented into vinegar or distilled into an alcoholic drink called feni, fenny, uraak, or arrack.
The seed or part that we call the nut is encased in a leathery, kidney-shaped shell at the end of the cashew apple. The leathery shell contains the caustic substance anacardic acid. Anacardic acid is similar to the uroshiol oil found in poison ivy and can produce severe skin lesions with the merest contact.
Now that we know cashews must be processed by heat we also know there's no point in paying extra money for those "raw, unprocessed" cashews sold at health food stores.