Cashew is a very popular nut belonging to the family Anacardiaceae. The English name of cashew comes from a Portuguese word. It is well grown in the tropical climates for the cashew nut and cashew apples. The name Anacardium refers to the shape of the fruit which resembles an inverted heart. Cashew tree is small, evergreen and attains a height of 10-12 meters with an irregular trunk. The leaves are somewhat spiral in shape, leathery textured, elliptic to ovate and measure about 4-22 cm in length and 2-15 cm in breadth with a smooth margin. The flowers are borne in a panicle or corymb measuring 26 cm long. The flowers are green but later on turn into red with five slender, acute petals and are 7-15 mm long. The fruit of cashew tree is an accessory fruit which is pear-shaped in structure developing from the pedicel and receptacle of the flower. The fruit is known as cashew apple and maranon in Central America. The fruit is pale and becomes red after ripening and 5-11 cm long. The fruit is edible with a sweet smell and sweet taste. The pulp of cashew apple is juicy but the skin is fragile so it creates difficulty in transport.
The true fruit of the cashew tree is a kidney shaped drupe which develops at end of the cashew apple. The drups develops first and then the pedicel expands into cashew apple. Within the fruit there is a single fruit known as cashew nut. In the botanical sense cashew nut is actually the seed. The seed is surrounded by a hard shell containing allergenic phenolic resin, anarcadic acid, and a poten skin irritant. The chemical nature of the skin irritant is exactly similar to that of allergenic oil known as urushiol. Some people are allergic to cashew nuts but the nuts are less allergic in comparison to other nuts and peanuts. Cashew is actually native to Brazil but the credit for the introduction of this nut in India goes to the Portuguese. From India the fruit got spread in Southeast Asia and Africa. The cashew nutshell liquid (CNSL) is a byproduct produced after the processing of the cashew nut rich in anacardic acids. The liquid is very effective in the treatment of teeth abscesses caused by the Gram positive bacteria. The bark is scraped and soaked and boiled and used for treating diarrhea. The gum obtained from the tree is used in varnishing. The seeds are ground to make powders to be used as antivenom against the snake bites. The nut oil bears antifungal properties. Anacardic acid is used for the production of cardanol which is used as a frictional and coating material.
The cashew nut is used as a popular snack which is either salted or sugared. The nuts are also covered in chocolate and are somewhat cheaper than peanuts and almonds. The nut is also an important agent in Thai, Chinese and Indian cuisines. In Indian cuisines they are used for garnishing sweets as well as other preparations. In India, particularly in Goa the cashew apple is marshed and the juice obtained is kept for fermentation for 2-3 days. The fermented juice then undergoes double distillation resulting in the production of a beverage called as feni. The nuts are good source of energy, carbohydrates, sugars, fat, protein, dietary fibers, vitamin B-complex, vitamin C, calcium, magnesium, phosphorous, zinc and iron. The fats and oils present in the cashew nut oil contain 54% monounsaturated fat, 18% polyunsaturated fat and 16% saturated fat and 7% stearic acid.