From PROTA
(Plant Resources of Tropical Africa, Ressources végétales de l’Afrique
tropicale)
by Dominique
Louppe, Akwasi Asamoah, C. Antwi-Bosiaka, Kwasi
Frimpong-Mensah, Acheampong Atta-Boateng, C. S. Montes
Taxon
Blighia sapida K.D.Koenig
Protologue
Ann. Bot. 2: 571, t. 16–17 (1806).
Family
Sapindaceae
Chromosome
Numbers
2n = 32
Vernacular
Names
Ackee,
akee, akee apple, savory akee tree (En). Aki, fisanier, blighia
savoureuse, fausse anacarde, pommier d’aki, arbre fricassé (Fr).
Castanheiro de Africa, castanha de Africa, huevo vegetal castanha (Po).
Origin and
Geographic Distribution
Blighia
sapida
occurs naturally from Senegal to Cameroon and Equatorial Guinea, and
possibly also in Gabon. It is commonly planted in its natural area of
distribution, as fruit tree and ornamental shade tree. It has been
introduced in many other tropical countries and in some subtropical
regions such as Florida (United States) and is widely cultivated as
fruit and ornamental tree in India and tropical America. It had already
been introduced in tropical America by the end of the 18th century, and
has since become locally naturalized.
Uses
Wood
of Blighia sapida,
known as ‘achin’ or ‘tsana’, is mainly used for light construction and
furniture, but sometimes also for casks, boxes, crates, food
containers, packing cases, tool handles, paddles, pestles, mortars,
handicrafts, carving and turnery. It is suitable for interior trim,
joinery and railway sleepers. In Ghana, it is used as a substitute for
niangon (Heritiera utilis
(Sprague) Sprague). The wood is also used as firewood and for charcoal
production.
Blighia
sapida
is commonly planted as ornamental shade tree. It is considered useful
for soil improvement and erosion control. In traditional medicine, sap
from terminal buds is instilled in the eyes to treat ophthalmia and
conjunctivites. Bark and leaf decoctions are administered to treat
oedema, intercostal pain, dysentery and diarrhoea. In Ghana, bark
ground-up with capsicum pepper (Capsicum
annuum
L.) is rubbed on the body as stimulant and pulp of ground leafy twigs
is rubbed on the forehead to treat migraine. In Côte d’Ivoire and
Nigeria, ground leaves are applied as a paste together with plant salts
to treat yaws and ulcers. In traditional medicine in Côte d’Ivoire, Blighia sapida
is widely used for the treatment of yellow fever, epilepsy and oedema,
and as a laxative and diuretic. The seeds are taken in Ghana to control
nausea and vomiting. In Benin, leaves are used in the treatment of
fever and vertigo, and twigs to treat hepatitis, cirrhosis and
amygdalitis. In Togo, decoctions of bark or fruit walls are applied to
wounds, and the fruit pulp to treat whitlow. Pounded bark is
administered as an antidote to snake and scorpion bites, and pounded
seeds to treat stomach complaints. Aqueous seed extracts are
administered to expel parasites in Brazil. The pounded fruit is used as
fish poison. Green fruits lather in water and are used by the Krobo
people of Ghana as soap for washing and as a mordant for dyeing. Dried
fruit husks are rich in potash and the ashes are used in making soap.
Seeds of Blighia sapida
yield a yellowish oil, believed to be edible.
In Nigeria the seeds are used in making traditional soap.
Mature
seed arils are eaten. They are not largely consumed in Africa, but
considered a delicacy in some other parts of the world where Blighia sapida
has been introduced. Ackee is also the national fruit of Jamaica.
Boiled arils are an ingredient of a popular traditional dish in
Jamaica, together with salt fish. In West Africa arils are sometimes
eaten raw, fried or roasted. However, the arils of unripe seeds are
toxic, as well as the seeds. An ink for tattoos is made from the seeds.
Production
and international trade
Blighia
sapida
timber has no importance on the international market, and even local
importance seems to be limited because in many areas within its
distribution area it occurs in low densities. However, in a study in
south-western Nigeria, Blighia
sapida was found to be one of the most commonly logged and
processed timber species.
The
arils are commercially traded, mainly from Jamaica to American and
European markets. Canned arils form the major product, in 2001 about
1.7 million kg, with frozen arils much less important with 13,000 kg.
Orchards of Blighia
sapida
have also been established in Florida (United States), Mexico and Costa
Rica. In 2005 total production of arils was valued at US$ 400 million.
In Africa, the trade is local. In 1992 in northern Côte d’Ivoire, the
price of 3 arils was about 10 FCFA.
Properties
The heartwood of Blighia
sapida
is orange-brown or reddish brown, and distinctly demarcated from the
whitish sapwood. The texture is moderately coarse. The wood has little
lustre. It is moderately heavy and hard. It is easy to work with both
machine and hand tools. The wood moulds and sands well and takes an
attractive finish. It is suitable for turnery. It is moderately durable
and is quite resistant to termite attack.
The composition of 100 g
of raw aril is approximately: water 58 g, protein 9 g, fat 19 g,
carbohydrate 10 g, fibre 3.5 g, Ca 83 mg, P 98 mg, Fe 5.5 mg, thiamin
0.1 mg, riboflavin 0.2 mg, niacin 3.7 mg and ascorbic acid 65 mg.
A
water-soluble and heat-stable toxic compound, hypoglycin A, is present
in the aril of unripe seeds, as well as in the seed and in the pinkish
to reddish tissue at the base of the aril. The Jamaican vomiting
sickness is associated with this compound and is characterized by
vomiting, generalized weakness, altered consciousness and sometimes
even death. Hypoglycemia and depression of the central nervous system
are common. The aril of fully ripe seeds after natural dehiscence of
the fruit is nearly free of the toxic compound. The consumption of
unripe seed arils has probably caused many cases of encephalopathy in
children in Burkina Faso and other West African countries. The seeds
contain about 26% of oil which is suitable for industrial applications.
Extracts
of unripe fruits produced neutropenia and thrombocytopenia in mice,
suggesting that they may be useful in the treatment of diseases such as
chronic myeloid leukaemia, essential thrombocythaemia and polycythaemia.
Description
Usually
evergreen, dioecious, small to medium-sized tree up to 25(–30) m tall;
bole branchless for up to 15 m and straight and cylindrical, but often
much shorter and crooked or twisted, up to 80(–120) cm in diameter,
often with small buttresses; bark surface usually smooth but with
lenticels in horizontal lines, grey to pale brown, inner bark granular,
yellow to brown or pinkish, often mottled orange; crown dense and
rounded; young twigs grooved, yellow-orange hairy, becoming glabrous.
Leaves alternate, paripinnately compound with 3–5 pairs of leaflets;
stipules absent; petiole 0.5–2.5 cm long, slightly winged, rachis up to
20 cm long; petiolules stout, up to 6 mm long; leaflets opposite,
elliptical to obovate, 5–15 cm × 3.5–8 cm, lowest pair smallest,
cuneate to rounded at base, rounded to short-acuminate at apex, margins
entire or slightly wavy, papery or thinly leathery, dark green,
slightly hairy below, pinnately veined with 8–14 pairs of lateral
veins. Inflorescence an axillary, slender false raceme up to 20 cm
long, hairy. Flowers probably functionally unisexual, regular,
5-merous, greenish white to greenish yellow, sweet-scented; pedicel up
to 6 mm long, elongating up to 10 mm in fruit; calyx with tube about as
long as lobes, 2–3 mm long; petals free, rhomboid, 3–4 mm long, hairy,
with a 2-lobed scale on the inner face; stamens 6–10, free, filaments
up to 6 mm long, hairy in lower part; ovary superior, hairy, usually
3-lobed and 3-celled, style short; male flowers with rudimentary ovary,
female flowers with reduced stamens. Fruit an obovoid to pear-shaped
capsule 3.5–10 cm × 3–5 cm, slightly 3-lobed, yellow to red when ripe,
glabrous, dehiscing with 3 woody valves hairy inside, usually 3-seeded.
Seeds ovoid, 2–2.5 cm long, glossy black, with cream-coloured to yellow
cup-shaped aril up to 2 cm long at base. Seedling with hypogeal
germination; epicotyl c. 15 cm long, hairy; first 2 leaves opposite,
with 3 elliptical or obovate leaflets up to 10 cm × 3.5 cm.
Other
botanical information
Blighia
comprises 3 species and originates from tropical Africa. Blighia sapida can
be distinguished from the other two species by its large fruits with
rounded lobes
Anatomy
Wood-anatomical description (IAWA hardwood codes):
Growth
rings: 2: growth ring boundaries indistinct or absent. Vessels: 5: wood
diffuse-porous; 13: simple perforation plates; 22: intervessel pits
alternate; 23: shape of alternate pits polygonal; 25: intervessel pits
small (4–7 μm); 30: vessel-ray pits with distinct borders; similar to
intervessel pits in size and shape throughout the ray cell; (36:
helical thickenings in vessel elements present); (37: helical
thickenings throughout body of vessel element); (38: helical
thickenings only in vessel element tails); 42: mean tangential diameter
of vessel lumina 100–200 μm; 46: ≥ 12 rays per mm. Mineral inclusions:
136: prismatic crystals present; 138: prismatic crystals in procumbent
ray cells.
(S. N’Danikou, P.E. Gasson & E.A. Wheeler)
Growth and
development
Initial growth of Blighia
sapida
is fast on moderately fertile soils. Seedlings grow best in gaps in the
forest canopy, with a mean annual height increment of 70 cm. Blighia sapida
is classified as a non-pioneer light demander. It has an extensive
rooting system. In pure stands at a spacing of 3.5 m × 3.5 m in
northern Côte d’Ivoire, the fastest growing trees reached 4 m tall 3
years after planting and the canopy was closed after 4.5 years. In
Cameroon, young trees raised from seed started flowering after 5 years
and first fruits developed after 7 years. In Florida, trees raised from
seedlings start producing fruit after 3–6 years, while grafted trees
produce fruit in 1–2 years.
Blighia
sapida
has been recorded to flower twice a year, first at the end of the dry
season and a second time at the end of the rainy season. Fruits mature
about 6 months after flowering, but in orchards fruit development may
take only 2 months. It has been recorded that only about 4% of female
or apparently bisexual flowers develop into a mature fruit.
All-year-round flowering and fruiting have been recorded in tropical
America. The flowers are pollinated by insects such as bees. Although
trees in the natural area of distribution seem to be dioecious (male
and female flowers on different trees), it has been reported in Jamaica
that they are andro-monoecious (with male and bisexual flowers produced
on the same tree). The seeds are probably dispersed by animals such as
large birds and monkeys.
Ecology
Blighia
sapida occurs most commonly in semi-deciduous forest, but
can also be found in evergreen forest as well as in forest outliers in
savanna regions. In Côte d’Ivoire, it is most common in the transition
zone between dry and moister forest and in gallery forest. It has been
planted successfully in villages in much drier zones in Mali and
Burkina Faso. The natural habitat of the species is obscured by the
common planting around villages and further spread from there into the
forest. It prefers well-drained deep fertile soils, but occurs also on
non-fertile sandy soils and limestone. In drier regions it is often
found on termite mounds. It does not tolerate waterlogged soils and
cannot withstand flooding. It shows some resistance to fire.
Propagation
and planting
Generally, Blighia
sapida regenerates fairly well naturally. The weight of a
seed is about 3 g. Seeds are sensitive to desiccation and are
considered short-lived. It is recommended to sow them within a few days
after extraction from the fruit. However, seeds can be kept for 3
months in moist storage at 21°C. Germination starts after 2–4 weeks,
with a germination rate of 80%. In Florida, seeds are sown in
germination boxes and germination is said to take normally 2–3 months.
Seedlings should be watered regularly in the nursery before
transplanting. It is recommended to transplant in full sunlight and at
a spacing of 4 m for timber production and 6–9 m for fruit production.
For planting, Blighia
sapida is usually propagated by seed, but cuttings can
also be used; these readily develop roots under proper conditions.
Propagation by grafting and air layering was also successful.
Management
In areas with occasional flooding, mounds of 60–90 cm high are made
before transplanting of seedlings to ensure plant survival. In Florida
and other regions where Blighia
sapida is planted for commercial fruit production, young
trees are fertilized every 1–2 months during the first year. Topping
the main shoot at a height of about 5 m is recommended to facilitate
fruit harvesting. It is recommended to control tree form by pruning
several times when the tree is grown for timber production. Trees often
sprout vigorously from stumps.
In Benin, the most common management practices to improve fruit
production are pruning, protection against livestock, fire protection,
mulching of seedlings and saplings, and association with annual crops.
In northern Côte d’Ivoire, trees have generally a private owner,
whereas most other trees are collective property.
Diseases and
pests
In Florida, an attack by Verticillium
dahliae has been recorded, causing wilt and dieback. In
Jamaica, stem galls are common.
Harvesting
Arils for fresh consumption should be picked from dehisced fruits,
which ensures that the seeds and arils are fully ripe and that arils do
not contain serious amounts of toxin. Another appropriate method is to
collect unopened but ripe fruits from the tree and lay them on racks in
the sun. Arils can be harvested from the fruits when they have opened
after about 3 days.
Yield
In Florida, a tree may produce 45–68 kg of fruits per year.
Genetic
resources and breeding
There seems to be no reason to consider Blighia sapida to
be under threat of genetic erosion. It is quite widespread and is
commonly planted. Research in Benin showed that Blighia sapida has
moderate levels of genetic diversity in Benin and little
differentiation among populations and climatic zones. Nine distinct
criteria, mostly related to fruit characteristics, have been used to
differentiate between types.
Breeding
In Jamaica, some different fruit types of Blighia sapida have
been developed, mainly differing in the aril, which may be soft and
yellow or firm and cream-coloured.
Prospects
Wood of Blighia sapida
is currently not commercially important, but it is a multipurpose tree,
being a source of edible fruits (arils) and traditional medicine, and
being popular for planting as ornamental shade tree. Blighia sapida is a
nice ornamental tree, especially when decorated with the brightly
coloured fruits. It is also considered useful for planting to improve
soil fertility and to reduce erosion through its large rooting system.
In 2003 Blighia sapida
emerged as a high-priority species for domestication in Benin after a
national survey.
Extensive research has been carried out on the toxicity of different
parts of the fruit. The edible arils certainly offer possibilities for
economic development in tropical Africa, but lessons learnt from
tropical America and Burkina Faso regarding the toxicity of compounds
should be taken into serious consideration. Educational campaigns are
needed to prevent fatalities. More pharmacological studies are
recommended in view of the wide applications of different plant parts
in traditional medicine. The seed oil is promising for industrial use,
especially as lubricant and speciality surfactant.
Literature
• Akintayo, E.T., Adebayo, E.A. & Arogundade, L.A., 2002.
Chemical composition, physicochemical and functional properties of akee
(Blighia sapida)
pulp and seed flours. Food Chemistry 77(3): 333–336.
• Aubréville, A., 1959. La flore forestière de la Côte d’Ivoire.
Deuxième édition révisée. Tome troisième. Publication No 15. Centre
Technique Forestier Tropical, Nogent-sur-Marne, France. 334 pp.
• Burkill, H.M., 2000. The useful plants of West Tropical Africa. 2nd
Edition. Volume 5, Families S–Z, Addenda. Royal Botanic Gardens, Kew,
Richmond, United Kingdom. 686 pp.
• Ekué, M.R.M., Gailing, O., Finkeldey, R. & Eyog-Matig, O.,
2009. Indigenous knowledge, traditional management and genetic
diversity of the endogenous agroforestry species ackee (Blighia sapida) in
Benin. ISHS Acta Horticulturae 806: International symposium on
underutilized plants for food security, nutrition, income and
sustainable development. pp. 655–661.
• Janick, J. & Paull, R.E. (Editors), 2006. Encyclopedia of
fruit and nuts. CABI, Wallingford, United Kingdom. 954 pp.
• Meda, H.A., Diallo, B., Buchet, J.P., Lison, D., Barennes, H.,
Ouangré, A., Sanou, M., Cousens, S., Tall, F. & van de Perre,
P., 1999. Epidemic of fatal encephalopathy in preschool children in
Burkina Faso and consumption of unripe ackee (Blighia sapida)
fruit. The Lancet 353: 536–540.
• Omobuwajo, T.O., Sanni, L.A. & Olajide, J.O., 2000. Physical
properties of ackee apple (Blighia
sapida) seeds. Journal of Food Engineering 45: 43–48.
• Oteng-Amoako, A.A. (Editor), 2006. 100 tropical African timber trees
from Ghana: tree description and wood identification with notes on
distribution, ecology, silviculture, ethnobotany and wood uses. 304 pp.
• Vivien, J. & Faure, J.J., 1985. Arbres des forêts denses
d’Afrique Centrale. Agence de Coopération Culturelle et Technique,
Paris, France. 565 pp.
• World Agroforestry Centre, undated. Agroforestree Database.
[Internet] World Agroforestry Centre (ICRAF), Nairobi, Kenya.
http://www.worldagroforestry.org/ resources/databases/
agroforestree. Accessed October 2009.
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