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Anacardium occidentale (Cashew)

Kasjoe, Kasjoeboom [Afrikaans]

Life > eukaryotes > Archaeoplastida > Chloroplastida > Charophyta > Streptophytina > Plantae (land plants) > Tracheophyta (vascular plants) > Euphyllophyta > Lignophyta (woody plants) > Spermatophyta (seed plants) > Angiospermae (flowering plants) > Eudicotyledons > Core Eudicots > Rosids > Eurosid II > Order: Sapindales > Family: Anacardiaceae

Anacardium occidentale (Cashew Nut)  

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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