Cashew - Anacardium occidentale


TAXONOMY

The Cashew, Anacardium occidentale L., is a member of the Anacardiaceae family, along with mango, pistachio, poison ivy and poison oak. The family contains 73 genera and about 600 species. Anacardium contains 8 species, native to tropical America, of which the cashew is by far the most important economically.

Cultivars
    Cashews are one of the few fruit crops normally grown from seed, and few improved cultivars exist, at least in commercial production.

ORIGIN, HISTORY OF CULTIVATION

    Cashew is native to northeastern Brazil, in the area between the Atlantic rain forest and the Amazon rainforest. The Portuguese introduced cashew to the west coast of India and east Africa in the 16th century, shortly after its discovery in 1578. It was planted in India initially to reduce erosion, and uses for the nut and pseudofruit, the cashew apple, were developed much later. Nut domestication  predated the arrival of Europeans to Brazil, although international nut trade did not occur until the 1920s. India developed more refined methods for removing the caustic shell oil, and this country is given credit for developing the modern nut industry. 
PRODUCTION

World (2004 FAO) - 2,082,101 MT, or 4.6 billion lbs. Produced commercially in 32 countries on over 7.5 million acres. Cashew is now the #1 tree nut crop in the world, since its production surpassed that of almond in 2003. Average yields worldwide are about 600 lbs/acre.

Top 10 countries
(% of world production)
1. Viet Nam (28)  
6. Indonesia (4)
2. India (25) 7. Guinea-Bissau (4)   
3. Nigeria (10) 8. Cote D'Ivoire (4)
4. Brazil (8) 9. Mozambique (3)
5. Tanzania (6) 10. Benin (2)

    Cashews produce 2 additional products of commercial value from their fruit: cashew apples and cashew nut shell liquid. The cashew apple is the juicy, swollen peduncle of the fruit.

United States - Cashews are not produced commercially in the USA. The USA imported 102,000 MT of cashew in 2003, valued at $398 million.

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BOTANICAL DESCRIPTION

Plant
    A small to medium tree, generally single-trunked and spreading in habit, up to 40' in height but generally 10-20' in cultivation (Figure 9.3). In older trees, spread may be greater than height, with lower limbs bending to touch the ground. Leaves are thick, prominently veined, oval to spatulate in shape, with blunt tips and entire margins. New foliage contains reddish pigment.

Flowers
    Flowering is similar to the close relative mango: both male and perfect flowers are borne in the same inflorescence (polygamous). Individual flowers are 1/4" across, with crimson petals, often striped longitudinally and reflexed. They are borne terminally on panicles, generally at the beginning of the dry season. Flowering may occur over several weeks.

Pollination
    Trees are at least partially self-fruitful, as lone trees can bear many fruit.  Various insects, even flies and ants provide pollination.

Fruit
    The true botanical fruit is a nut, about 1" long, shaped like a small boxing glove, hanging below a fleshy, swollen peduncle called the cashew apple or pseudofruit.  Fruit are borne singly or in small clusters, and mature in 60-90 days.


    The nut shell has an inner and outer wall, separated by a honeycomb tissue infused with caustic oil. Cracking the nuts fresh results in the oil contaminating the kernel, so nuts are roasted to drive off oils before they are shelled. The nuts are about 22-30% kernel by weight, and kernels are difficult to extract whole compared to other tree nuts.





GENERAL CULTURE

Soils and Climate
    Tolerant of sandy, poor soils, Soil pH 4.5-6.5, intolerant of poor soil drainage
    Drought tolerant if soils are deep, and can grow in areas receiving only 30-50" of rain per year
    High rainfall and humidity favor diseases that destroy the flowers and reduce fruit set
    No cold tolerance

Propagation
    Propagation is most often by seed, planted directly in the field where the tree is to be sited.

Rootstocks - generally none, but cashew seedlings can be used for rootstocks for grafted trees.

Planting Design, Training, Pruning
  Planting Design: 20-35 ft between trees and rows
  Cashews form open, spreading canopies naturally, and very little information on pruning exists.

HARVEST, POSTHARVEST HANDLING

Maturity
    The cashew apple and nut abscise from trees naturally when ripe. Maturation occurs over a period of several weeks during the dry season.

Harvest Method
    Nuts are collected from the ground by hand. Frequent passes though the planting must be made if apples are to be utilized, as they are highly perishable. Rain at harvest may increase rot and stimulate nut germination.

Postharvest Handling
    The presence of caustic cashew nut shell liquid (CNSL) in the shells makes cashew processing more difficult and hazardous than for other nut crops. After harvest, the nuts are dried in the sun or in simple tray driers and stored for processing later. Dried nuts can be stored for about 2 years at room temperature after reaching water contents of 5-10%. Nuts are re-hydrated partially by soaking or storing in high humidity since this facilitates extraction of whole kernels and CNSL. Nuts are separated by size before roasting to ensure uniformity of the roasting process. After roasting, nuts are shelled either by hand or in machines.

Storage
    Vacuum packed, roasted nuts can be stored for up to one year, and carbon dioxide packing extends life an additional year.

CONTRIBUTION TO DIET

    The cashew apple may be consumed fresh, but contains high quantities of tannins yielding a bitter taste and dry mouth feel. It is more often cooked, partially dried, or candied, as in the Dominican Republic and India. The alcoholic drink, Feni, is made from fermented cashew apple juice in India. The wine made from the juice is said to be the finest made from tropical fruits. Per capita consumption of cashew is 0.8 lbs/year in the USA.

Dietary value, per 100 gram edible portion  

 Cashew nut
Cashew apple
Water (%) 3-7
 86
Calories 578
 ---
Protein (%) 18-22
 0.1
Fat (%) 
46
 0.3
Carbohydrates (%)
27
 9-15
Crude Fiber (%)
1.1
 0.75

  % of US RDA*
Vitamin A 0
 0
Thiamin, B1 45
 ---
Riboflavin, B2 
12
 ---
Niacin 12
 ---
Vitamin C 0
 200-600
Calcium 0.2
 0.5
Phosphorus
5.8
 2
Iron 50
 5
Sodium 4.6
 <0.1
Potassium 12
 0.1
* Percent of recommended daily allowance set by FDA, assuming a 154 lb male adult, 2700 calories per day.