Aleurites moluccanus (PROTA)

Plant Resources of Tropical Africa Introduction

List of species

General importance
Geographic coverage Africa
Geographic coverage World
Cereal / pulse
Vegetable oil
Dye / tannin
Medicinal
Timber
Fuel
Ornamental
Forage / feed
Auxiliary plant
Food security

Aleurites moluccanus (L.) Willd.

Protologue: Sp. pl. 4(1): 590 (1805), as ‘moluccana’.

Family: Euphorbiaceae

Chromosome number: 2n = 22, 24, 44

Vernacular names

Candlenut tree, Indian walnut, lumbang tree, kukui nut (En). Bancoulier, noix des Indes, noix de bancoul, noix des Moluques (Fr). Noz da India, nogueira de Iguape, calumbàn (Po). Mkaa, mkaakaa (Sw).

Origin and geographic distribution

Since ancient times Aleurites moluccanus occurs from India and China, throughout South-East Asia, to Polynesia and New Zealand. It has also been introduced for cultivation in many tropical countries and has become the national tree of Hawaii. In Africa it is grown on a limited scale, e.g. in DR Congo, Tanzania, Uganda, the Comoros, Madagascar, and South Africa (KwaZulu-Natal and Mpumalanga).

Uses

The fatty seed oil (kukui oil or lumbang oil) is not suitable for cooking, but is used in cosmetics, industrially (in paints, varnishes, linoleum, soap manufacture, wood preservation), for illumination (lamp oil, candles) and medicinally (mild purgative, embrocation for sciatica, against hair loss). In Indonesia the oil is used in the batik industry. For illumination, the oily kernels can be burnt as such, or pounded and made into candles. The seed of Aleurites moluccanus is an indispensable spice in Indonesian cuisine, where it is known as ‘kemiri’. It possesses little flavour of its own, but mainly acts as a flavour enhancer. It is added to numerous dishes in small quantities, raw, or briefly roasted, pounded and mixed with other ingredients. In Hawaii a spice called ‘inamona’ is prepared from the seeds mixed with seaweed and salt. Raw seed is slightly poisonous, acting as a laxative, but the seeds of a type in Vanuatu are eaten without any apparent toxic effect. In Indonesia the residual oil cake is sometimes processed into a snack-food called ‘dage kemiri’. The presscake is an excellent organic fertilizer rich in N and P; it should be used with caution as animal feed because of its toxic effects.

Aleurites moluccanus is commonly planted in villages and as roadside tree. Its silvery-green foliage makes it an attractive ornamental in landscaping. It is also used for reforestation and to suppress weeds. Where the wood is abundantly available it is used for carving and to make furniture, small utensils and matches. It is suitable for paper pulp.

In traditional medicine in Indonesia the seed is used as a laxative, pulped kernels are used in poultices to treat headache, fevers, ulcers, swollen joints and constipation, the bark is used to treat dysentery, the bark sap (mixed with coconut milk) to treat sprue, and boiled leaves are applied externally to treat headache and gonorrhoea. In Japan the bark is used to treat tumours.

The hardness of the stone of the fruit is exploited in a gambling game in which the objective is to break the opponent’s stone by hitting it with one’s own. In Indonesia a special cultivar is grown for this purpose. In Hawaii the shells of the stones are used in making traditional garlands (‘leis’). In Polynesia dyes made from various parts of the tree were used on tapa cloth and canoes and in tattooing.

Production and international trade

In Indonesia there is a considerable internal trade in candlenuts, mainly with Java as the destination. In the late 1980s, annual exports of candlenuts were in the order of 400–600 t with a total value of US$ 200,000–500,000. Candlenut is traded and transported as stones or ‘nuts’. At the retail level, small quantities are marketed as seed (hard shell removed).

Properties

The weight of the stone of the fruit is 10–14 g; it is made up of shell (65–70%) and seed (30–35%). Per 100 g edible portion, dry seed of Aleurites moluccanus contains: water 5–8 g, protein 8–22 g, fat 60–62 g, carbohydrate 7–18 g, fibre 2–3 g, ash 3–4 g. The energy value is about 2675 kJ/100 g. Possessing very little flavour of its own, it seems that candlenut mainly acts as a flavour enhancer, making the taste buds temporarily more sensitive. The cold-pressed oil is pale yellow, with agreeable smell. When left to stand, it dries into a thin frosty film. The fatty acid composition of the oil is: palmitic acid 5–9%, stearic acid 2–7%, oleic acid 11–35%, linoleic acid 34–49%, linolenic acid 21–35%. The content of free fatty acids is generally very low. To improve the drying properties of the oil, it can be mixed with linseed oil and thermally polymerized (blown).

The moderate toxicity of the seed has been ascribed to a toxalbumin similar to the ones in Abrus and Ricinus spp. The wood is rather lightweight and not durable.

Adulterations and substitutes

Kukui oil resembles linseed oil, but its qualities for the paint industry are poorer.

Description

Large, evergreen, monoecious tree, up to 40 m tall; bole up to 1.5 m in diameter, bark grey, rather rough with lenticels; crown heavy, irregular, appearing whitish or frosted from a distance due to a cover of white stellate hairs especially on young parts. Leaves alternate, simple; stipules small, early caducous; petiole up to 30 cm long, bearing a pair of small, green-brown glands at the top on the upper side; blade in young trees and suckers circular in outline, up to 30 cm in diameter, with a cordate base and 3–5 triangular lobes, blade in adult trees ovate-triangular or ovate-oblong, 12–23 cm × 6–12 cm, apex pointed, curved and drooping, margins entire or slightly sinuate, dark green with a silvery gloss, pinnately veined. Inflorescence a terminal or axillary panicle composed of cymes, 10–20 cm long. Flowers unisexual, female flowers terminating the ultimate branchlets of the cymes, male flowers much more numerous, smaller, arranged around the female flowers in bunches; calyx 2–3-lobed at anthesis, stellate hairy; petals 5, lanceolate, 6–7 mm long in male flowers, 9–10 mm in female ones, white; disk glands 5; male flowers with 10–20 stamens, arranged in 3–4 series, the outer ones free, the inner ones fused; female flowers with 2–4-celled, stellate hairy ovary and 2–4, deeply 2-lobed styles. Fruit a drupe, laterally compressed, ovoid-globose and with 2 stones or semiglobose and with 1 stone, 5–6 cm × 4–7 cm, stellate hairy, indehiscent, olive-green with whitish flesh; endocarp thick, bony, rough. Seeds compressed-globose, up to 3 cm × 3 cm; endosperm thick, rich in oil.

Other botanical information

Aleurites is a small genus of 2 species. Formerly it was larger, but was divided into 3 genera: Aleurites comprising Aleurites moluccanus and Aleurites rockinghamensis (Baill.) P.I. Forst., a rainforest tree from Australia and New Guinea, Reutealis comprising a single species, Reutealis trisperma (Blanco) Airy Shaw, endemic to the Philippines, and Vernicia comprising 3 species, all from Asia, but widely cultivated. All these species yield oil and have been confused in the past.

Growth and development

Aleurites moluccanus first flowers when it is about 4 years old. Flowering can occur year-round, and flowers and fruits of all stages of development may be present on a tree. Fruits need 3–4 months to develop and mature. Growth is moderately fast, up to 1.5 m/year in height under favourable conditions. In the Philippines trees reached a height of 12.5 m with a stem diameter of 15 cm 8 years after planting.

Ecology

Aleurites moluccanus occurs in tropical and subtropical regions with at least 700 mm rainfall and a dry season of not more than 5 months; in drier areas it depends on permanent streams or subsurface water. In more humid areas it is found on well-drained sands near the coast and on limestone, but it is also present naturalized in mixed and teak forests. It requires a mean maximum temperature of the hottest month 26–30°C, a mean minimum temperature of the coldest month 8–13°C.

It occurs on various soils that should be well drained, with pH 5–8. It tolerates strong winds and some salt spray, but is not tolerant of waterlogging, fire or frost lasting several days.

Propagation and planting

Propagation of Aleurites moluccanus is usually by seed. Fruits are left to decay for a few days before stones are extracted. The hard-shelled seeds retain their viability for over a year. The hard shell, however, is also the cause of uneven and often slow germination. Germination percentage is usually low (30–40%), but can be improved by scarification by mechanical, physical or chemical means. Repeated warming and cooling of the stones, as well as sun-warming in a moist medium, have been tried to improve germination. Acid treatment has been recommended, but other reports indicate that it does not improve germination. Cracking the stone speeds up germination but may lead to fungal infections. Direct seeding is also possible as the young trees compete well with weeds. There are 100–120 seeds/kg (with shell).

Seeds are sown in a seedbed or in polythene bags at a depth of 3–10 cm. In the field the planting distance is 7–10 m × 7–10 m when grown for seed, whereas closer spacings of 4 m × 4 m are applied if pulpwood is the main objective. In windbreaks trees can be planted 3–4 m apart.

Vegetative propagation, e.g. by cuttings or marcotting, seems possible, but may produce trees with excessive vegetative growth.

Management

Established seedlings require little care. The leaves are renewed regularly, and old leaves left on the soil soon rot, enriching the soil with organic matter and nutrients. Trees coppice well, but regrowth is too slow to use them in hedgerows in agroforestry.

Diseases and pests

A root-collar disease caused by Ustulina deusta has been observed on Aleurites moluccanus in Indonesia. Botryodiplodia theobromae has been found to infest the wood, causing blue stain. No pests of economic importance occur.

Harvesting

Fruits of Aleurites moluccanus are allowed to fall and lie on the ground until the outer fruit wall has decayed, after which the stones are collected.

Yield

Yield estimates of Aleurites moluccanus vary from 2500–15,000 stones per tree per year, or 25–150 kg. This corresponds to 8–50 kg kernels per tree per year, or 5–30 kg oil per tree per year.

Handling after harvest

Most commercially available oil is expeller pressed. Grinding the whole stones and pressing the oil gives a rather low oil yield and the oil cake is of less value as organic fertilizer, but extracting the seeds from the stones is difficult.

Traditionally, a combination of mechanical (hammering) and physical (successive heating and cooling) methods is applied to crack the stone of Aleurites moluccanus. The best quality seeds for use as a spice are obtained by sun-drying the stones for 5–10 days, followed by mechanical cracking.

Stones may be stored for over a year without appreciable change in the amount and composition of the oil. Kernels cannot be stored for long, since they are attacked by beetles, and the oil acidifies.

To prepare the snack-food ‘dage kemiri’ the presscake is pounded, soaked for 48 hours in running water, steamed and then covered with a banana leaf with a weight on top of it to press out remaining liquid and left to ferment for 48 hours in a dark place.

Genetic resources

A living collection of Aleurites moluccanus is maintained by the Research Institute for Spice and Medicinal Crops (RISMC), Bogor, Indonesia.

Breeding

No breeding programmes are known to exist for Aleurites moluccanus.

Prospects

The oil of the candlenut tree will continue to be used in cosmetics and may find wider use in applications that currently use imported linseed oil or petrochemicals. However, it is still doubtful whether this will be economically viable. In Indonesia the value of ‘kemiri’ as a spice is uncontested. The use of the wood in the paper industry might become feasible in the long term. In Africa Aleurites moluccanus will probably remain of limited importance.

Major references

• Airy Shaw, H.K., 1966. Notes on Malaysian and other Asiatic Euphorbiaceae. Kew Bulletin 20: 393–395.

• Elevitch, C.R. & Manner, H.I., 2006. Aleurites moluccana (kukui), version 2.1. [Internet] In: Elevitch, C.R. (Editor). Species profiles for Pacific Island agroforestry. Permanent Agriculture Resources, Holualoa, HI, United States. http://www.agroforestry.net/ tti/Aleurites-kukui.pdf. January 2006.

• Gaydou, A.M., Menet, L., Ravelojaona, G. & Geneste, P., 1982. Ressources énergétiques d’origine végétale à Madagascar: alcool éthylique et huiles de graines oléagineuses. Oléagineux 37: 135–141.

• Heine, B. & Legère, K., 1995. Swahili plants: an ethnobotanical survey. Rüdiger Köppe Verlag, Köln, Germany. 376 pp.

• Kabele Ngiefu, C., Paquot, C. & Vieux, A., 1977. Les plantes à huile du Zaïre. 3: Familles botaniques fournissant des huiles d’insaturation relativement élevée. Oléagineux 32: 535–537.

• Katende, A.B., Birnie, A. & Tengnäs, B., 1995. Useful trees and shrubs for Uganda: identification, propagation and management for agricultural and pastoral communities. Technical Handbook 10. Regional Soil Conservation Unit, Nairobi, Kenya. 710 pp.

• Radcliffe-Smith, A., 1987. Euphorbiaceae (part 1). In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. 407 pp.

• Radcliffe-Smith, A., 1996. Euphorbiaceae, subfamilies Phyllantoideae, Oldfieldioideae, Acalyphoideae, Crotonoideae and Euphorbioideae, tribe Hippomaneae. In: Pope, G.V. (Editor). Flora Zambesiaca. Volume 9, part 4. Royal Botanic Gardens, Kew, Richmond, United Kingdom. pp. 1–337.

• Siemonsma, J.S., 1999. Aleurites moluccana (L.) Willd. In: de Guzman, C.C. & Siemonsma, J.S. (Editors). Plant Resources of South-East Asia No 13. Spices. Backhuys Publishers, Leiden, Netherlands. pp. 63–65.

• Stuppy, W., van Welzen, P.C., Klinratana, P. & Posa, M.C.T., 1999. Revision of the genera Aleurites, Reutealis and Vernicia (Euphorbiaceae). Blumea 44: 73–98.

Other references

• Ako, H., Kong, N. & Brown, A., 2005. Fatty acid profiles of kukui nut oils over time and from different sources. Industrial Crops and Products 22: 169–174.

• Brown, A.C., Koett, J., Johnson, D.W., Semaskvich, N.M., Holck, P., Lally, D., Cruz, L., Young, R., Higa, B. & Lo, S., 2005. Effectiveness of kukui nut oil as a topical treatment for psoriasis. International Journal of Dermatology 44(8): 684–687.

• Gaydou, E.M. & Ramanoelina, A.R.P., 1983. Etude de la composition en acides gras des huiles extraites de graines provenant de quelques plantes de Madagascar. Revue Française des Corps Gras 30(1): 21–25.

• Hadad, M.E.A. & Mansur, M., 1992. Plasma nutfah kemiri di Balai Penelitian Tanaman Rempah dan Obat [Candlenut-tree germplasm at the Research Institute for Spice and Medicinal Crops]. Proceedings of the National Seminar on Research and Development of Multi-purpose Trees, Cisarua, Bogor, Indonesia, 16–17 June 1992. pp. 249–254.

• Poteet, M.D., 2006. Biodiesel crop implementation in Hawaii. [Internet] The State of Hawaii, Department of Agriculture. 89 pp. http://www.hawaiiag.org/ hdoa/pdf/ biodiesel%20report%20(revised).pdf. January 2007.

• Semangun, H., 1988. Penyakit-penyakit tanaman perkebunan di Indonesia [Diseases of estate crops in Indonesia]. Gadjah Mada University Press, Yogyakarta, Indonesia. p. 335.

• Tapa Darma, I.G.K., 1993. Identifikasi jamur ‘blue stain’ yang menyerang berbagai jenis kayu [Identification of the blue-stain fungus attacking several timber species]. Technical Notes, Faculty of Forestry, Bogor Agricultural University 5(1): 27–32.

• World Agroforestry Centre, undated. Agroforestree Database. [Internet] World Agroforestry Centre (ICRAF), Nairobi, Kenya. http://www.worldagroforestry.org/ Sites/TreeDBS/ aft.asp. January 2006.

Sources of illustration

• Siemonsma, J.S., 1999. Aleurites moluccana (L.) Willd. In: de Guzman, C.C. & Siemonsma, J.S. (Editors). Plant Resources of South-East Asia No 13. Spices. Backhuys Publishers, Leiden, Netherlands. pp. 63–65.

Author(s)

• L.P.A. Oyen

PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article

Oyen, L.P.A., 2007. Aleurites moluccanus (L.) Willd. [Internet] Record from Protabase. van der Vossen, H.A.M. & Mkamilo, G.S. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. < http://database.prota.org/search.htm>. .

Accessed 18 December 2024.

• See the Prota4U database.