The plants belonging to the large Sapindaceae family (soapberry)are mainly tropical, but the Canadian maple and the European horse chestnut are part of them.
Sapindaceae are well represented in Asia with several fruit trees: lychee, rambutan, longan. In the West Indies and South America: Melicoccus bijugatus with sweet berries and guarana, a source of caffeine (and soft drinks).
Blighia sapida is native to West Africa mainly from Senegal to Gabon including Nigeria and neighboring countries.
This tree has been introduced in many countries with a tropical-equatorial climate, notably in Jamaica (where it is the national fruit in the same way as in Nigeria and South Africa) and in the neighboring West Indies (Haiti, Santo Domingo). ), the formerly British West Indies and in the Guyanas (Guyana and Surinam).
It is rare in the French West Indies where it is called "ris de veau" or "yeux de crabe" and "fricasser tree" in Haiti.
Blighia sapida is generally a small, slow-growing tree, the leaves are persistent, quite tough (compound, paripinnate). The flowers are small, very fragrant, white (bisexual or unisexual).
The fruit is shaped like an angular pear, it changes from green to reddish brown (sometimes rather yellowish) as it ripens.
When ripe, it opens and reveals 2 to 4 shiny black seeds (most often 3) topped with a soft, white-yellow aril (fleshy envelope), with a creamy appearance connected to the seed by reddish filaments.
The mature aril is the edible part of the ackee, the seeds are toxic, the slightly toxic leaves are part of local pharmacopoeias in Africa.
CHEMICAL COMPOSITION AND PROPERTIES
ARIL OF BLIGHIA SAPIDA FRUIT
This is the only edible part and you must wait until the fruit is ripe, that is to say when it has burst, when it has opened for a short time.
AVERAGE CHEMICAL COMPOSITION for 100 g of fresh aril
- Approximately 60% water,
- 10 g of assimilable carbohydrates (giving it a slightly sweet taste),
- 18 to 20 g of lipids (with a slightly nutty taste),
- 9 g of proteins,
- 3 to 5 g of fiber,
- mineral salts: calcium, iron, phosphorus,
- 60 to 70 mg of vitamin C and some B vitamins in small quantities.
Aril also contains substances potentially active from a medical point of view:
- alkaloids: small quantity of toxic hypoglycin A and B and very small quantity of other alkaloids (nicotine, caffeine, quinine),
- phenolic compounds: notably vanillic and gallic acids,
- saponins notably Blighoside A
Ripe aril is therefore nourishing due to its fat and protein content, and dietary due to its Vitamin C content.
But it also contains small quantities of toxic compounds, or those which can disrupt digestion.
The amount of toxic compounds varies in the fruit:
- When it is green (immature) there is a lot of toxic compound hypoglycin A, during maturation this toxic substance "migrates" towards the seeds (and is transformed into HYPOGLYCIN B) but persists in the filaments which connect the seed to the aril.
- Secondarily the quantity of toxic products will increase if the fruit remains on the tree for too long or if it falls to the ground.
HOW DOES HYPOGLYCIN A WORK?
It is a toxin that acts on the functioning of the liver (liver toxin).
It blocks the action of several compounds which allow the body to transform fats stored in tissues into glucose, which is absolutely necessary for the proper functioning of the body (blocking glucogenesis).
Signs of intoxication appear 12 to 24 hours after the ackee meal, sometimes earlier if the quantity of fruit absorbed is significant, especially in an otherwise malnourished child.
The body exhausts its other glucose reserves and this causes hypoglycemia associated with digestive disorders:
- sudden onset with vomiting and abdominal pain, but generally no diarrhea,
- neurological disorders fairly quickly (loss of consciousness, convulsions, disorders skin sensitivity) which indicate the seriousness of the situation.
- if left untreated, death can occur within 12 to 24 hours.
Children are more susceptible than adults to this poisoning.
There is no antidote against hypoglycin A; hypoglycemia and the effects of vomiting (dehydration) are corrected with glucose or dextrose infusions. The practice of gastric lavage is controversial (generally unnecessary due to the delay in the appearance of symptoms).
The level of intoxication is proportional to the quantity of toxin ingested (number of fruits and level of maturity).
If the symptoms are not too severe, recovery occurs in 4 to 7 days during which sugary drinks or easy-to-digest carbohydrate foods are regularly consumed.
In case of chronic poisoning, signs of toxic hepatitis (jaundice) may appear.
Other fruit trees have fruits which before maturity can contain toxic doses of a compound close to hypoglycin A, this is the case of lychee which is part of the same plant family as ackee. Cases of hypoglycemic encephalopathy (30% fatal) have been observed in children in India, Bangladesh and Vietnam.
There is a laboratory method (liquid chromatography coupled with mass spectrometry) to search for hypoglycin or its metabolites, particularly in fruits but also in canned goods or the digestive contents of a sick person after ingesting ackee.
THE LEAVES and BARK OF BLIGHIA SAPIDA
All parts of this tree are used in West Africa by traditional practitioners, including the poisonous seeds.
The leaves are the most used, they contain numerous pharmacologically active compounds:
- alkaloids: hypoglycine A and B, nicotine, caffeine, quinine and many others in very small quantities,
- phenolic compounds: notably phenolic acids and tannins, quercetin, epicatechin, gallic, caffeic, ellagic, chlorogenic acid...
- saponins typical of this plant: Blighoside
This set of active products is a little toxic due to the presence of hypoglycin and saponins, but powerfully anti-inflammatory and free radical scavenger due to its content of phenolic compounds.
The aqueous extracts of leaves (which contain a little quinine) have an antiplasmodial action (on Plasmodium berghei) in mice infected with this plasmodium, a cousin of the malaria agent but not active in humans.
The bark extract is also anti-inflammatory and dries mucous membranes due to the presence of tannins.
ACKEE or AKI, A NOURISHING AND DIETARY FRUIT
The fruit should be picked from the tree when it has just opened, not when it is still green and has not fallen to the ground.
It is necessary to separate the edible aril from the seed and the filaments which join them.
You can eat arils:
- fresh without preparation, the vitamin C is intact, it is a little sweet and it recalls the taste of hazelnuts or peanuts due to its high fat content.
- cooked in many ways, often in soup but its taste is refined when fried, and it accompanies vegetables, meat or fish. Cooked in a pan it looks like scrambled eggs.
Cooked ackee is a national dish in Jamaica paired with cod, local fruits and vegetables.
Picked at the right time and well prepared, it is digestible and safe when consumed in “reasonable” quantities.
Ackee arils are exported canned or frozen, but there are regular checks on their toxic hypoglycin A content.
There is a small export market in the USA, Canada and UK, which is subject to specific regulations.
USES OF LEAVES
Let us cite some traditional uses in West Africa.
Crushed leaves are used as plasters to treat chronic or recurrent skin ulcers.
The unfusion of leaves is recommended to treat:
- febrile episodes: seasonal viral infections, bouts of malaria, and even yellow fever,
- diarrheal digestive disorders (dysentery),
- internal bleeding (digestive, urinary, genital),
- diabetes in adults (type 2 diabetes)
- sometimes high blood pressure and migraines.
Among all these indications we can retain as possible the use of the infusion of leaves in cases of viral infections and type 2 diabetes.
In ADULT African people naturally less sensitive to malaria, it is possible that the infusion of Blighia sapida leaves help alleviate malaria attacks but it is not recommended for a child or a pregnant woman.
There are other traditional uses of seeds, bark, buds or young branches but they seem a little dangerous to me except perhaps the use of the sap that is collected at the end of a small branch like anti-inflammatory eye drops in the absence of a more “modern” drug.
OTHER USES OF BLIGHIA SAPIDA
It is a resistant tree with evergreen foliage that is planted in villages or towns to provide shade.
Its wood is of good quality, usable in carpentry and cabinetmaking, it produces very good charcoal.
There are plantations of Blighia sapida intended solely for wood production.
Its very fragrant flowers are used to make toilet lotions.
Crushed green fruits are used as fishing poison (presence of saponins)
The fruit's husk contains enough saponins to be used as vegetable soap with water.
The seeds contain oil which is collected by pressing or cooking but which is not edible; it can be used to make soap by gently heating it mixed with a basic compound (potash or soda).
CULTIVATION OF BLIGHIA SAPIDA
It adapts to many types of soil (it is found in the clearings of the great equatorial forest but also in the savannahs). It tolerates the temporary cold of subtropical climates (south Florida for example).
Propagation is mainly by seeds which germinate easily but do not survive long. They must be sown shortly after harvest or stored in the cold in the presence of humidity.
The speed of germination depends on the temperature: 2 to 3 weeks in warm (tropical) regions, 2 to 3 months in Florida (subtropical).
You can also take cuttings which root quite easily and graft if you want to maintain a cultural variety.
The trees being male or male and female, it is necessary to plant several trees to be sure to harvest fruit.
BLIGHIA SAPIDA ACKEE or AKI with edible but potentially toxic fruit.
BLIGHIA SAPIDA, native to West Africa, has fruits whose arils are edible, nourishing and dietary.
However, this aril is toxic if the fruit has not reached maturity, that is to say before it bursts naturally and shows seeds and arils.
The seeds are toxic, the leaves are sometimes used for traditional medicine in Africa.
Copyright 2023 : Dr Jean-Michel Hurtel