Everyone knows the excellent flavour of the cashew nut, but how many have tasted the juicy fruit of this plant, brought to Asia from tropical America by the Portuguese? In fact, the true fruit is what is known everywhere as he nut, and the "fruit" sold for eating is a swollen stem.
The cashew tree is widely known in tropical Asia for its medicinal properties. All parts of the tree contain a sap which is irritant, including the thin membrane between the actual nut and its hard casing. The cashew apple has a very thin skin-green when unripe and turning to yellow, pink, or more rarely, bright scarlet, when ripe.
Because of its fragility, it is not a widely available "commercial" fruit. It can, however, be found at fruit stalls near cashew-growing regions. The slightly elongated fruit is about 7 cm (2 1/2 inches) long, with an interior of white flesh. Eat the fruit only when fully ripe or it is unpleasantly astringent. The ripe fruit is sweet, crisp and juicy with a faint rose perfume.
Uses of cashew apple
In cashew-producing countries, the nut is only one of the products enjoyed by the local populations. The cashew "apple" or false fruit is an edible food rich in vitamin C. It can be dried, canned as a preserve or eaten fresh from the tree. It can also be squeezed for fresh juice, which can then be fermented into cashew wine, which is a very popular drink in West Africa. In parts of India, it is used to distil cashew liquor referred to as feni. In some parts of South America, local inhabitants regard the apple, rather than the nut kernel, as a delicacy. In Brazil, the apple is used to manufacture jams and soft and alcoholic drinks.
The cashew tree bears a false fruit known as the cashew apple from which the nut protrudes. The cashew apple is between three and five inches long and has a smooth, shiny skin that turns from green to bright red, orange or yellow in colour as it matures. It has a pulpy, juicy structure, with a pleasant but strong astringent flavour.
The cashew apple is very rich in vitamin C (262 mg/100 ml of juice) and contains five times more vitamin C than an orange. A glass of cashew apple juice meets an adult individual's daily vitamin C (30 mg) requirement. The cashew apple is also rich in sugars and contains considerable amounts of tannins and minerals, mainly calcium, iron and phosphorous. Furthermore, the fruit has medicinal properties. It is used for curing scurvy and diarrhoea and it is effective in preventing cholera. It is applied for the cure of neurological pain and rheumatism. It is also regarded as a first-class source of energy.
Until recently, the potential of cashew apple had not been investigated due to its highly astringent and acrid taste which is believed to originate in the waxy layer of the skin and which causes tongue and throat irritation after eating. Cashew fruit can be made suitable for consumption by removing the undesirable tannins and processing the apples into value-added products, such as juices, syrups, canned fruits, pickles, jams, chutneys, candy and toffee. The recommended methods for removing the astringent properties of the cashew apple include steaming the fruit for five minutes before washing it in cold water, boiling the fruit in salt water for five minutes or adding gelatin solution to the expressed juice.
The fruit should be picked from the tree by hand to avoid bruising the delicate flesh. They are then carefully washed and the nuts are removed for processing. Cashew apples should be processed within two to three hours of picking, since they undergo rapid deterioration when kept for a longer time.
Currently only six percent of cashew apple production is exploited, since the producer only has a guaranteed market for cashew nuts. It is also extremely difficult to use the whole fruit commercially as the apple ripens prior to the nut. The quality of nuts detached from the green fruit, is unacceptable for commercialization.
The ripe apple can be eaten or used for jam making, for the production of fruit juices or for making alcoholic beverages. The development of processing options for the cashew apple has also been limited by its high degree of perishability and consequent difficulties in transportation from growing areas to distant processing plants.