Cashews, a popular snack and ingredient, often spark curiosity about their origins, with many wondering if these distinctively shaped kernels truly come from a tree. The answer is yes; cashews are indeed the edible seeds of a specific tropical tree. They possess a unique growth habit that sets them apart from many other commonly consumed nuts. Originating from tropical regions, the cashew tree provides these flavorful seeds, from cultivation to consumption.
The Cashew Plant’s Unique Growth
The cashew tree, known scientifically as Anacardium occidentale, is a tropical evergreen species that can grow quite tall, some varieties reaching up to 14 meters (46 feet). It exhibits an unusual method of fruit and seed development. What is commonly recognized as the cashew “nut” is not a true botanical nut but rather a seed, encased within a hard, kidney-shaped shell. This seed develops at the end of a fleshy, pear-shaped structure called the cashew apple. The cashew apple is a “false fruit” or accessory fruit, forming from the flower stem after the true fruit (the seed) begins to develop.
This unique arrangement means the cashew seed hangs below the cashew apple. The hard outer shell of the cashew seed contains a caustic phenolic resin, which is a potent skin irritant. This compound is chemically related to urushiol, the irritant found in poison ivy. The presence of this irritating substance in the shell is a significant factor in how cashews are harvested and processed.
Harvesting and Processing Cashew Nuts
Due to the presence of urushiol in their shells, raw cashews cannot be eaten directly from the tree, as handling them can cause skin irritation or allergic reactions similar to those from poison ivy. To render them safe and edible, cashews undergo a multi-step processing sequence that neutralizes these toxic compounds.
Harvested cashew seeds are dried in the sun for several days. The next step involves heat treatment, usually through roasting or steaming, which destroys the urushiol within the shell. This process also softens the hard shell, making it easier to crack open. After heating, the cashews are shelled. The kernels are then peeled and graded based on size and quality before packaging.
Global Cultivation and Economic Impact
Cashew trees thrive in warm, humid tropical conditions. Native to northeastern Brazil, the cashew tree was spread globally by Portuguese explorers in the 16th century, primarily to India and Africa. Today, major cashew-producing countries include Ivory Coast, India, and Vietnam, with other significant contributions from countries like Brazil and Tanzania.
Cashew trees require consistent warm temperatures and adapt to a wide range of rainfall conditions. The global trade of cashews is substantial, supporting the economies of many tropical nations.