Cashews

Cashew (Anacardium occidentale L.) a native of Eastern Brazil introduced to India just as other commercial crops like Rubber, Coffee, Tea etc. by the Portuguese nearly five centuries back. The first introduction of cashew in India was made in Goa from where it spread to other parts of the country. In the beginning it was mainly considered as a crop for afforestation and soil binding to check erosions. The nuts, apple and other by products of this crop are of commercial importance. Though its commercial exploitation began from the early 1960s, marginal lands and denuded forests were the areas set apart for the plantation development. Because of its adaptive ability in wide range of agro climatic conditions it has become a crop of high economy and attained the status of an export oriented commodity bringing considerable foreign exchange to the country. It is closely related to the Mango and Pistachio plants. Cashews are found growing on cashew trees or “bushes†near the equator.

            Cashew trees flourish in extreme heat in the tropics and are readily found near the equator. The tree isn’t more than 30 feet tall (like an apple or cherry tree) and often they are mistaken for bushes because the limbs spread easily, strike the ground, and reroot themselves. The trunk is gnarled and tortuous, giving the tree an unkempt appearance.

            The highly unusual cashew fruit consists of both a crab apple (called the cashew apple), and a kidney bean shaped appendage on the end of the fruit called the cashew nut. The apple is shaped like and is the same size as a pear; when ripe, it is a brilliant yellow, red or scarlet color. Like all fruit trees, a flower emerges and the nut grows from the center of the flower. The receptor or “apple†is a later swelling between the flower and the nut—forming the cashew apple. After harvesting, the cashew apple keeps for only 24 hours before the soft fruit deteriorates. The cashew apple is not commercially important since it spoils quickly, but local people love the fruit. To harvest the nut, the ripe apple is allowed to fall to the ground where it is easily gathered by natives. The apple and nut are separated.
            The gray/brown cashew nut hangs like a nose at the end of the cashew apple. The nut shell is 1–1/2 inches long and kidney shaped. The nut is found on the end closest to the cashew apple. The other end is honeycombed with cells. These cells contain a toxic resinous fluid called cardol that blisters the mouth. For many years, the cashew was referred to as the blister nut. Inside the hard shell is a slightly curved white cashew kernel which is about 7/8 inches long and is wrapped in a thin brown skin called a testa which is removed during the processing. The cashew nut, therefore, has two shells—the hard exterior shell and the testa.

            There are two ways to remove the cashew shell, the inside fluid and the thin brown skin. Washing the raw nut in a water bath and storing it in moist heaps or silos for 12 hours makes the shells brittle as long as they maintain 7% to 10% humidity. The shell will rupture and liberate cardol fluid. The older method is to roast the whole nut in shallow pans over an open charcoal fire with constant agitation. The process was used in native marketplaces and was dangerous and disagreeable. Shells burst, spurting the caustic fluid and releasing clouds of acrid fumes which blistered the skin. At the same time, the heat caused the caustic fluid to dissipate.
            Modern extraction methods are to put the nuts in a large perforated cylinder which rotates at a declining angle above the heat. As the nut travels down through the roasting cylinder, the liquid flows from the shell and is collected in troughs and commercially sold. Some kernels get scorched because they become overheated near the bottom of the pile. These become second and third grades in quality. As the nuts emerge from their journey, they are water sprayed and set aside to cool and dry.
            Nut cracking in small batches is done manually by native laborers. They place the nut on a hard flat stone and crack the brittle shell, hitting it with a wooden mallet. This manual cracking results in many broken kernels which bring a lower market price. Cashews are graded on how white they are and how broken the kernel is.