Cashew nut

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I. GENERAL

COMMON NAME

Cashew Nut

BOTANICAL NAME

Anacardium occidentale

FAMILY

Anacardiaceae

OTHER NAME

Casa, Maranon, Merey (Spanish), Noix d'anacarde, Pomme de caju (French), Caju (Portuguese), Kaju (Hind))

CULTIVATION CONDITIONS

While the tree is native to central and South America it is now widely distributed throughout the tropics, particularly in many parts of Africa and Asia.

The cashew tree will tolerate a wide range of conditions including drought and poor soil, but cannot withstand cold or frost. In East Africa it grows between sea level and 1000m in areas of 500mm rainfall or more (Acland).

MAJOR PRODUCING COUNTRIES

TANZANIA, INDIA, Mozambique, Sri Lanka, Brazil, Kenya, Madagascar, Thailand, Malaysia, Indonesia, Nigeria, Senegal, Malawi, Angola.

Global production is estimated at 0.38 mt. World Bank data estimates that 97% of production is from wild trees and only 3% is from established plantations (Rosengarten).

YIELD AND DESCRIPTION

Yields of up to 7000 - 9000 kg/ha of cashews are possible, giving 150-300 kg shelled nuts per ha. Trees generally start producing in the third year after planting with full yields of 30 kg of nuts being obtained after 8-10 years. They then continue to yield for about 30 years. The cashew fruit consists of a peduncle and a seed. The peduncle, often called the false fruit, is pear shaped, yellow or red in colour and made up of a soft juicy pulp. The seed which develops below the peduncle is kidney shaped and resembles a large bean. Internally the seed contains the kernel or cashew nut of commerce surrounded by an oily liquid-cashew nut shell liquid. The kernels contain 47% oil.

MAIN USES

The main market is as a high value edible nut. Cashew yields two "oils". One of these, found between the seed coat (or pericarp) and the nut, is called cashew nut shell liquid (CNSL). It is not a triglyceride and contains a high proportion of phenolic compounds. It finds use in industry as a raw material for brake lining compounds, as a waterproofing agent, a preservative, and in the manufacturing of paints and plastics. It is toxic and corrosive to the skin. Cashew apples are sometimes made locally into drinks, wines and pickles. In some countries they are also osmo-sol dried to produce a date-like caramel.

An edible oil can be extracted from cashew nuts but no evidence of this being carried out commercially has been found. Due to the high value of cashew nuts even small pieces find a market in confectionery products.

II. AGRICULTURAL ASPECTS

CULTIVATION

Many trees are found growing wild. The plant germinates poorly, those that are cultivated are propagated by seed which are planted at a rate of 2-3 per hole due to poor germination rates (Gibbon).

A distinction is made between trees producing red apples and trees producing yellow apples (Woodroof).

Major pests attacking the cashew: In Tanzania and Sri Lanka the Helopeltis antonii or tea mosquito has been a problem. It causes inflorescence blight which damages the leaves and fruit. In Kenya Pseudotheraptus wayi, which is also a pest in coconut production, can cause the same problems as Helopeltis spp. The cashew stem and root borer damages causes damage during growth. Mites, thrips and leaf cutting ants may also cause economic damage (Acland).

Major diseases noted include: Pink disease (Corticium ,salmonicolor), has been noted in some areas to cause branch die back. Pythium, Fusarium, and Phytophthora spp may bring about damp off to seedlings. Colletotrichum gloeo-sporioides damages false fruits (Acland).

HARVESTING PERIODS

In East Africa harvesting starts in August and lasts until March. Peak harvesting is between October and December.

In India the main crop is ready for harvest between March and April. Some trees may produce an additional light crop between October and November (Woodroof).

In both cases, harvesting is preferable before the cashew apple has fully formed to reduce losses caused by birds and animals attracted to the brightly coloured fruit.

HARVESTING METHODS

Ripe cashews can be picked from the tree but it is recommended that they are allowed to fall to the ground before they are gathered. This is to ensure that no unripe fruits are harvested.

The nuts rot quickly, therefore it is recommended that during fine weather harvesting should not be allowed to lapse for periods of more than one week. If nuts are left on the ground for longer than a week the seed coats become brown and rotten (Rosengarten). In wet weather nuts should be collected daily as they rot quickly.

III. POST HARVEST TREATMENT. PRESERVATION. AND STORAGE

PRE-TREATMENT

When the nuts are collected the cashew apple remains attached to the nut. This is removed by hand with a twisting action. Any pieces of the apple remaining on the nut are also removed (Acland).

Immediately after harvest, the nuts are sun dried for a few days until they have a moisture content of 8% or until the kernel is heard rattling inside the nut (Rosengarten). Drying also helps to mature the cashew seed.

After drying, the seeds can be stored in bags or bulk for a few days before processing. After processing the cashew nuts can be stored for up to a year in air tight containers.

Drying - the nuts are placed on bamboo mats or palm leaves and are regularly turned over using rakes. Raised barbecues are also used to hasten drying with the nuts being placed in layers on top of the barbecue not more than 10cm thick and raked using wooden tools so that the nuts are uniformly spread for sun drying (Russell).

After drying, the seeds can be stored in bags or bulk for a few days before processing.

IV. PROCESSING

PROCESSING METHODS

CNSL removal - before the shell is removed from the nut the CNSL is extracted. The traditional method of removing CNSL in East Africa involves roasting the nut in drums or baths. The roasting process not only removes the corrosive CNSL but also makes the shell brittle, thereby aiding the cracking process. This method results in the loss of most or all of the CNSL. To extract and retain CNSL the nuts are roasted in baths at a temperature of 180-185 deg C. Vents in the equipment dispel the unpleasant fumes. This method recovers 85-90% of the liquid (Acland).

The traditional method of extracting CNSL in India involves roasting the nuts in a shallow pan over open charcoal fires. Constant agitation is required to prevent the nuts from becoming scorched. This method is extremely unpleasant as the shells burst releasing CNSL and fumes with resulting losses (Woodroof).

An improved method involves roasting the nuts in a perforated pan with troughs placed underneath to catch the liquid.

At a larger scale whole nuts are placed in rotating perforated cylinders inclined at an angle above a heat source. As the nuts fall downwards the shell liquid flows through the holes and is collected in troughs. The nuts are then water sprayed and set aside for cooling. (Solvent extraction can also be used to extract CNSL from the shells.)

Shelling - Shelling cashew nuts is unpleasant work and the hands of workers should be protected. The nuts and the shellers hands are commonly dusted in wood ash. This absorbs any CSNL remaining on the shell, preventing it from damaging the worker's hands and contaminating the kernels (Acland). In India skilled women crack the nuts. They use lime ash, linseed or castor oil to protect their hands. They squat on the floor, place the nut onto a hard stone and crack it open with a mallet (Woodroof).

Woodroof (1967) mentions a machine in Tanzania that is capable of shelling nuts whilst keeping the kernels intact. The operators hands are covered in oil for protection and the nut is placed inside a gripper. This moves against a circular saw and cuts a groove into the shell. A bladed instrument is then inserted within the grooves and the shell is removed.

A sheller designed by the Technology Development Unit of Thailand (See Appendix II), uses a lever operation to cut open the shell. Nuts are then removed by hand.

Commercial larger scale decorticators are available.

After shelling the kernels are dried to remove a thin skin which covers them.

After processing the cashew nuts can be stored for up to a year in air tight containers.

OIL EXTRACTION

No documentation of commercial oil extraction has been identified. Oil, however, can readily be extracted with simple presses and expellers.

V. MAJOR FATTY ACIDS OF OIL

OIL COMPOSITION

(Source: Ecky)

The oil is light yellow, sweet, odourless and can be stored for long periods without becoming rancid.

BY PRODUCTS

The press cake from the extraction process would be suitable for use in human and animal feed.

EQUIPMENT

Roasting baths/drums with troughs to catch the CNSL, water spraying equipment for cooling, and shelling machines.

There is a lack of identifiable information for the following areas: AGRICULTURAL ASPECTS, planting period, OIL EXTRACTION, processing methods, nomenclature of products and equipment.

BIBLIOGRAPHY

ACLAND, J.D. "East African Crops", pp.29-32, FAO and Longman, 1977. BRUCHER, H. "Useful plants of Neotropical Origin and their Wild Relatives", p.215, Springer-Verlag, 1989.

ECKY, E.W. "Vegetable Fats and Oils", pp.613-616, Reinhold Publishing Corp, 1954.

GIBBON, D. PAIN, A. "Crops of the Drier Regions of the Tropics", pp.66-67, Longman Singapore Publications (Pte) Ltd. 1981. HALL, F.J. BANKS, L. "Cashew Nut processing" Reprinted from Tropical Science, Vol VII, 1, p.12.

MARTIN, F.W. "Handbook of Tropical Food Crops", pp.238-239, CRC Press Florida, 1984.

PESCE, C. "Oil Palms and Other Oilseeds of the Amazon", pp.92-93, Reference Publications Incorporated, 1985.

ROSENGARTEN, F. "The Book of Edible Nuts", Walker and Co New York, 1984.

RUSSELL, D.C. "Cashew Nut Processing", FAO Agricultural Services Bulletin, No.6, 1979.

VAUGHAN, J.G. "The Structure and Utilisation of Oil Seeds", Chapman and Hall, 1976.

WOODROOF, J.G. "Tree Nuts, Production, Processing and Products", Vol I, pp.221-225, AVI Publications Co, 1967.

Chinese vegetable tallow

I. GENERAL

COMMON NAME

Chinese Vegetable Tallow

BOTANICAL NAME

Sapium sebiferum syn. Stillingia sebifera

FAMILY

Euphorbiaceae

OTHER NAMES

U-kau-shu (Cantonese), Arbol del sebo (Spanish), Tallowberry

CULTIVATION CONDITIONS

The Chinese Tallow tree, which requires a sub-tropical climate, is indigenous to China. It has been introduced to other countries, particularly North India (Godin) .

MAJOR PRODUCING COUNTRIES

China, India, USSR

YIELD AND DESCRIPTION

The deciduous Chinese Tallow tree produces two kinds of fat from the same fruit. The outer coating, or mesocarp, covering the seeds yields a solid fat known as Chinese Vegetable Tallow, while the kernels contain a drying oil known as stillingia oil. The fruit is a three lobed capsule some 15 mm in diameter which opens when ripe and contains the kernel, about the size of a pea, surrounded by the solid fibrous and fatty mesocarp. Its structure allows the separation of the two oils with little contamination one with another. The fruit consists of 27-33% tallowy seed coat, 3641% shell and 29-35% kernel (dry basis). Both the outer seed coat and the kernel are very high in fat 55-78% and 53-64% respectively.

It is estimated that trees planted at a density of 370-395 per ha will produce 1340 kg fruit/ha. An average yield per tree is about 14-22 kg fruits which contain about 40% tallow and oil (Godin). The cake remaining after oil extraction is seldom used for animal feed. (Godin), (Bo Gohl).

MAIN USES

Tallow oil can be used to make soap, candles and an edible oil which is consumed in China. Stillingia oil is used as a drying oil in paints and varnishes. It is considered by some to be superior to linseed oil for these purposes (Godin). In addition, a black dye has traditionally been extracted from the leaves and used in the silk industry in China.

II. AGRICULTURAL ASPECTS

CULTIVATION

The tree can be grown from seed planted at 3-4 per hole with 5m spacings (Godin).

HARVESTING PERIOD

In China, harvesting takes place between September and November.

HARVESTING METHODS

The ripe fruits are plucked from the trees or branch ends. Chopping the fruits down causes severe damage to the trees (Godin).

III. POST HARVEST TREATMENT, PRESERVATION, STORAGE

PRE-TREATMENT

The fruits are placed on mats and left to dry in the sun. This causes them to blacken and split open.

IV. PROCESSING

PROCESSING METHOD

After drying, the seeds are removed from the fruits by hand or with small threshers.

A traditional method used in China involves steaming the seeds in perforated cylinders and allowing the melted fat to run off, after which the seeds are crushed separately for the recovery of Stillingia Oil. Another method involves crushing the seeds between fluted roller" thereby stripping off the outer seed coat without breaking the kernel (Ecky).

An alternative process involves the removal of tallow and fibre stirring the fruits in warm water to disintegrate the seed coat. The slurry produced is washed over a screen which retains the seeds whilst the seed coat slurry passes through. The slurry is then filtered using a vacuum filter to recover solid material which is dried at 100 deg C (Godin) .

OIL EXTRACTION

From the separated fibre Chinese Vegetable tallow is extracted by solvent extraction or expression in cage presses.

The seeds are then crushed and subjected to solvent extraction using hexane. The Stillingia oil released from the seed during this procedure is recovered from the hexane by a vacuum distillation process. Traces of solvent present in the extracted oil are removed in the final stage where the hot oil is sparged with carbon dioxide gas (Godin).

MAJOR FATTY ACID COMPOSITION OF OIL

Tallow oil

(Source: Hilditch)

EQUIPMENT

Small threshers, screening/washing equipment, filters, cage presses, expellers, solvent extraction equipment and driers.

NOMENCLATURE OF PRODUCTS

In China, vegetable tallow is known as "pi-yu" whilst stillingia oil is known as "ting-yu". A mixture of them both is called "mou-ieou".

Additional information was not identifiable for the following areas: GENERAL, production; AGRICULTURAL ASPECTS, varieties, planting period, major pests and diseases; POST HARVEST, pre-treatment, storage methods and equipment; PROCESSING, nomenclature of products and by products.

BIBLIOGRAPHY

BO GOHL, Tropical Feeds. FAO, 19755555, p. 204

ECKY, E.W. "Vegetable Fats and Oils", pp.597-599, Reinhold Publishing Corp, 1954.

GODIN, N.J. SPENSLEY, P.C. "Oils and Oilseeds", pp.15-18, Crop and Product Digests No. 1, Tropical Products Institute, 1971.

HILDITCH, T.P., WILLIAMS, P.N. "The Chemical Composition of Natural Fats", 1964, Chapman Hall.

Cohune palm

I. GENERAL

COMMON NAME

Cohune Palm

BOTANICAL NAME

Orbignya cobune

FAMILY

Palmaceae

OTHER NAMES

Corozo, Coquito, Coco de aceite

CULTIVATION CONDITIONS

The crop requires a tropical climate and grows well in areas of high rainfall. It is a characteristic species of the rainforests in South America (Godin).

MAJOR PRODUCING COUNTRIES

Mexico, Honduras, Belize, Paraguay, Guatemala, El Salvador, Nicaragua

YIELD AND DESCRIPTION

Approximately 20 000 tonnes of nuts per annum were produced in 1987 (Dransfield). Individual palms produce about 1000-2000 fruits per annum in large bunches yielding l 500 kg/ha. The individual fruits are egg shaped, about 5-8 cm long and up to 5 cm in diameter. The fruit has an outer husk and a pulpy fibrous mesocarp surrounding the nut. Inside the very hard nut shell is a kernel approx. 30 mm long, 18 mm in diameter and weighing 5 g. The kernel contains 65-72% oil (Godin). The outer pulpy portion of the fruit also contains about 13% oil. This pulp is, however, not considered to be of commercial interest (Private Communication).

MAIN USES

The oil contained within the kernel is somewhat similar to coconut nut oil. When refined the oil is suitable for margarine production, baking and biscuit making. Damaged kernels can be used as cattle feed. The shells are a good source of fuel. The cake remaining after oil extraction also finds use in animal feed.

II. AGRICULTURAL ASPECTS

CULTIVATION

Most palms grow wild at a density of 15 palms per ha.

III. PROCESSING

PROCESSING METHODS

The nuts have a hard shell which is difficult to crack and have a high ratio of shell to kernel. The pressure required to crack the nuts is estimated at between 4 and 9 tonnes. Most nuts are cracked by hand, an extremely laborious task, machines have been developed to crack the nuts. One such mobile machine mounted on and powered by a truck has been developed in Belize, however, no data is available on its efficiency (Purseglove).

The oil is extracted by small expellers. It is recommended that the seeds be heated or scorched prior to expelling (Private Communication).

FATTY ACID COMPOSITION OF OIL

(Source: Godin)

EQUIPMENT

Sharp knives for cracking. Mechanical crackers, seed cooking kettles, Oil expellers or presses, filters.

There is a lack of identifiable information for the following areas: GENERAL, other names; AGRICULTURAL ASPECTS, varieties, planting period, major pest" and diseases, harvesting period and harvesting methods; POST HARVEST, pretreatment, preservation, storage methods and equipment; PROCESSING METHODS, OIL EXTRACTION, nomenclature of products.

BIBLIOGRAPHY

ANON, "Underexploited Tropical Plants with Promising Economic Value", National Academy of Sciences, 3rd Print, 1977.

DRANSFIELD, S. JOHNSON, D. SYRIGE, H. "Palms of the New World, A Conservation Census", IUCN-WWF Plants Conservation Programme, Publication No.2, 1987.

ECKY, E.W. " Vegetable Fats and Oils ", pp 362-363, Reinhold Publishing Corp., 1954.

GODIN, N.J. SPENSLEY, P.C. "Oils and Oilseeds", pp.30-32, Crop and Product Digests, No. 1, Tropical Products Institute, 1971.

PRIVATE COMMUNICATION, ITDG

PURSEGLOVE, J.W. "Tropical Crops: Monocotyledons", Longman, 1985.

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