Cashews are actually the kidney-shaped seeds that adhere to the bottom of the cashew apple, the fruit of the cashew tree, which is native to the coastal areas of northeastern Brazil.
The cashew tree made its way to Goa, India, between 1560 and 1565 via Portuguese sailors. From there it spread throughout Southeast Asia and eventually Africa.
Cashew nuts are produced in tropical countries because the tree is frost sensitive, adapting to various climatic regions between the latitudes of 25°N and 25°S.
The cashew tree is large and evergreen, growing to 14 m (46 ft) tall, with a short, often irregularly shaped trunk.
The leaves are spirally arranged, leathery textured, elliptic to obovate, from 4 to 22 cm (1.6 to 8.7 in) long and from 2 to 15 cm (0.79 to 5.91 in) broad, with smooth margins.
The flowers are produced in a panicle or corymb up to 26 cm (10 in) long; each flower is small, pale green at first, then turning reddish, with five slender, acute petals from 7 to 15 mm (0.28 to 0.59 in) long. The main pollinators are bats and insects.
The fruit of the cashew tree is an accessory fruit or false fruit . The term false fruit (accessory fruit) is sometimes applied to a plant structure that resembles a fruit, but is not derived from a flower or flowers. Called the cashew apple, it ripens into a yellow and/or red structure from 5 to 11 cm (2.0–4.3 in) long. It is edible and has a strong “sweet” smell and a sweet taste.
The true fruit of the cashew tree is a kidney or boxing-glove shaped drupe that grows at the end of the cashew apple. The drupe develops first on the tree, and then the pedicel expands to become the cashew apple. Within the true fruit is a single seed, which is often considered a nut, in the culinary sense.
The seed is surrounded by a double shell containing a caustic phenolic resin, urushiol, a potent skin irritant toxin also found in the related poison ivy in the sumac family. Some people are allergic to cashews, but cashews are a less frequent allergen than some other nuts.
There are 553 Calories calories in 100 grams (3.5 ounces) of raw cashews.
Cashews are about 21% protein, 46% fat, and 25% carbohydrates.
Cashews are very nutritious and are packed with protein and essential minerals including copper, calcium, magnesium, iron, phosphorus, potassium, and zinc. Sodium is also present in very small quantities. Cashews also contain vitamins such as vitamin C, vitamin B1 (thiamin), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B6, folate, vitamin E (alpha-tocopherol), and vitamin K (phylloquinone). Cashews also contain a high content of oleic acid (an omega-9 fatty acid that is also found in olive oil).
Some of the health benefits of cashews include a healthy heart, strong nerve and muscle function, aid in the formation of red blood cells, and an improved bone and oral health. They also good for your eyes and help regulate blood sugar control, increase HDL cholesterol, and increase fat oxidation. With its high antioxidant content, cashew nuts also help in boosting the immune system and preventing the formation of cancer cells.
In Western countries cashews are eaten mainly as a premium-quality snack food. They have a rich, buttery taste.
The so-called “raw cashews” available in health food shops have been cooked but not roasted or browned.
Cashews are commonly used in South and Southeast Asian cuisine and are a characteristic ingredient of numerous chicken and vegetarian dishes of southern India.
Cashew oil is a dark yellow oil for cooking or salad dressing pressed from cashew nuts (typically broken chunks created during processing).
Cashews also can be processed into cashew cheese or cashew butter which is similar to peanut butter.
The shell of the cashew seed yields derivatives that can be used in many applications including lubricants, waterproofing, paints, and arms production, starting in World War II.
The cashew apple can be eaten fresh, cooked in curries, or fermented into vinegar, as well as an alcoholic drink. It is also used to make preserves, chutneys, and jams in some countries such as India and Brazil.
In traditional Maya medicine, the leaves or bark of cashew trees can be made into a tea to treat diarrhea.
Its English name derives from the Portuguese name for the fruit of the cashew tree caju, which itself is derived from the Tupian word acajú, literally meaning “nut that produces itself.”