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CASHEW NUT PROCESSING
Introduction
The cashew tree is evergreen. It grows up to 12 metres high and has a spread of 25 metres.
Its extensive root system allows it to tolerate a wide range of moisture levels and soil types,
although, commercial production is advisable only in well-drained, sandy loam or red soils.
Annual rainfall needs to be at least 889mm
(35
inches) and not more than 3048mm
(120 inches). Cashew trees are most
frequently found in coastal areas.
The main commercial product of the
cashew tree is the nut. In the main
producing areas of East Africa and India,
95%
or more of the apple crop is not
eaten, as the taste is not popular.
However, in some parts of South America
and West Africa, 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. In Goa, in India, it is used to distil
a cashew liquor called feni.
The cashew fruit (figures 1 and 2) is
unusual in comparison with other tree nuts since the nut is outside the fruit. The cashew apple
is an edible false fruit, attached to the externally born nut by a stem. In its raw state, the shell
of the nut is leathery, not brittle. It contains the thick vesicant oil, CNSL, within a sponge-like
interior. A thin testa skin surrounds the kernel and keeps it separated from the inside of the
shell. The primary products of cashew nuts are the kernels which have value as confectionery
nuts. Cashew nut shell liquid (CNSL) is an important industrial raw material for resin
manufacture and the shells can be burned to provide heat for the decorticating operation.
Figure 1: Cashew Fruit
Figure 2: Cross-section of a Cashew Fruit
Cashew
Apple
Kernal
Tasta
Skin
Nut Shell