FRUIT-Y Surprise! Cashew Nuts Grow Out of an Apple!

The familiar cashew nut has a fascinating and unusual origin, emerging not from underground or within a typical fruit (Review), but as a small, kidney-shaped appendage at the base of a much larger, brightly colored structure. This vibrant, pear-shaped or apple-shaped entity, often yellow or red, is known as the cashew apple. Botanically, the fleshy cashew apple is not the true fruit of the cashew tree, but rather a swollen stalk or pedicel. The actual fruit is the hard, gray, kidney-shaped shell that dangles beneath it, and inside that shell is the single edible seed we call a cashew. Interestingly, the nut fully develops first, and only then does the cashew apple begin to swell and mature.

The processing of cashews is quite intricate due to a natural defense mechanism. The raw cashew nut shell contains a caustic, toxic (Review) resin called anacardic acid, which is related to the irritant found in poison ivy. Direct contact with this oil can cause severe skin irritation and burns, which is why cashews are never sold in their raw, unshelled form. To make them safe for consumption, the nuts undergo a careful process of roasting or steaming to neutralize the toxic oils before the inner kernel is extracted.

Originating in northeastern Brazil, the cashew tree was spread globally by Portuguese explorers in the 16th century, finding ideal growing conditions in tropical regions of India and Africa. While the nut is highly prized worldwide, the cashew apple itself is also consumed in many producing regions. It is juicy and rich in Vitamin C, often eaten fresh, pressed into juice, or fermented into alcoholic beverages, though its extreme perishability limits its distribution far from where it is harvested.