Anacardium occidentale (Cashew) Kasjoe, Kasjoeboom [Afrikaans]
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> Eudicotyledons > Core Eudicots > Rosids > Eurosid II > Order: Sapindales > Family: Anacardiaceae
Cashew trees are native to Brazil and were distributed
round the world by Portuguese explorers in the 1500's. They are grown
extensively in Mozambique and also in Maputoland (northern
KwaZulu-Natal). Cashew nuts should not be eaten raw because they are
surrounded by a very acrid, irritant oil - this oil is burnt off in the
roasting process (note that cashews in the stores labelled "raw", have
in fact been roasted). Besides being very tasty, cashews are a good source of
protein (about 17% by weight).
Cashew trees are native to restinga vegetation
on coastal dunes of northeastern Brazil where they are exposed to onshore winds
with salt spray. In order to survive in such a habitat they have long tap roots
with extensive lateral roots so that they can make the most of soil moisture
when available.
The Cashew nut itself is contained in a tough exterior
covering that contains a poisonous oil. The stalk of the fruit (i.e. the
pedicel) is enlarged into a pear-shaped red or yellow false fruit called the
cashew apple which is attractive to seed dispersers such as bats and monkeys. A
plant can grow from seed to seed producer within three years.
Advantageous properties of Cashew trees
- Produce cashew nuts. These contain about 17% protein and are rich in
minerals (calcium, phosphorus and iron) and vitamins (vitamins A, D, K and
E).
- The cashew apple juice can be drank as fresh juice, turned into vinegar,
or turned to wine that can then be distilled to produce brandy. It is also
used in jams, jellies, chutney and candied fruit. Cashew apple is rich in
vitamin A and very rich in vitamin C (about 150-400 mg per 100 g fresh
weight, which is about five times that in orange juice).
- They make good shade trees because of having evergreen
leaves and a wide-spreading canopy.
- Sap with insecticidal properties can be tapped from the
trunks. It can also be used as a varnish.
- They can be cut down for firewood and charcoal.
History of exploitation
It is unknown how long indigenous people in the Brazilian
region have utilised cashew nuts and apples but they were already doing so at the time of
European colonisation in the 1500's. Juice is squeezed from the cashew apples
and fermented to produce wine. Brazilian indigenous people roasted nuts over a fire
thus burning off the toxic outer covering and this method was copied by the
Portuguese colonisers. Brazilian indigenous people grew Cashew trees outside their
homes, partly for shade, and established them beyond their indigenous coastal
distribution. Cashew trees were also popular to the European colonisers so that
by 1750 they were widely distributed throughout tropical America.
Cashew trees were introduced to India by the Portuguese in
the 1500's where they came to be grown mainly for producing wine and brandy.
India is now a major World producer of cashew liquor. From India, Cashews were
introduced to other Asian countries. The earliest record of Cashews growing in
Africa is from the late 18th Century. Cashews have spread widely in the Indian
Ocean region and have become naturalised in seashore habitats.
Trade in cashew nuts started at the beginning of the 20th
Century and grew particularly fast in in 1930's, being dominated mainly by
India. Around about 1960 there was rapid growth in the industry, particularly in
India, Madagascar and Mozambique. Research was initiated by the Indians in
producing better cultivars although cultivated Cashews still remain much the
same as their wild counterparts. In the 1960's the Cashew story completed a full
circle by coming back to its land of origin in Brazil where large commercial
plantations were set up together with processing factories.
The shell surrounding the green cashew
nut kernel contains a very acrid and irritant oil. The nut itself contains
poisonous oils which need to be evaporated through roasting before the nut
can safely be eaten (note that cashews in the stores labelled "raw",
have in fact been roasted - very confusing).
References
-
Sauer, J.D. 1993. Historical geography of
crop plants - a select roster. CRC Press, Boca Raton, Florida.
-
van Wyk, B.-E. 2005. Food Plants of the World -
Identification, Culinary Uses and Nutritional Value. Briza, Pretoria.
Text by Hamish Robertson
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