The shea butter tree or simply shea tree is a tree of the African savannah (between 1000 and 1500 mm of annual rainfall) present from the Atlantic Ocean to the borders of the Red Sea, south of Sahelian areas in the north, Congo in the south.
It is usually a spontaneous tree (wild), preserved by the African populations.
Its growth is very slow but its longevity can reach several hundred years.
The shea is chunky with a large trunk with cracked and thick bark that protects it a bit from bush fires.
The leaves are in bunches at the ends of the branches (20cm long and 5 to 7 cm wide), with a slightly wavy margin.
They fall to the ground during the dry season.
Flowers in umbels are white, they appear before the leaves (in the dry season), and attract pollinators (bees and other Hymenoptera).
The fruits in clusters are ovoid 4 to 8 cm long, with fleshy edible pulp, they have one to two oleaginous kernels.
Vitellaria paradoxa is called multiple local names in Africa, but elsewhere it is known in French as the "karité" (after a name of Wolof origin) or in English "shea butter tree" (after a name of Bambara origin).
The medicinal parts are the leaves, the bark of small branches and roots, and the oleaginous kernels.
The shea butter tree, like many of sapotaceae, also contains latex.
CHEMICAL COMPOSITION AND PROPERTIES
SHEA TREE KERNELS
The almonds (kernels) of the shea fruit contain:
20 à 50 % fat.
Immature kernels (fruits picked from the tree) contain less fat than fruit almonds (fallen to the ground).
Triglycerides (fats) are mainly of two types: stearic-oleic-stearic and oleic-stearic-oleic.
The percentage of fatty acids is variable according to the regions and the different varieties of shea butter tree:
Stearic acid: 25 to 50%
Oleic acid: 35 to 60%
Palmitic acid: 3 to 8%
Linoleic acid: 1 to 10%
Arachidic acid: 0 to 3.5%
It can be noted the very small amount or the absence of essential fatty acids (linolenic acid). Shea butter is a nutritious dietary fat but quite "unbalanced" from a dietary point of view.
When shea butter contains a significant percentage of oleic acid it is fluid.
It is much firmer even hard when the percentage increases in stearic acid.
Some parts of Africa (especially at altitude) are known to produce a very firm shea butter (Mossi plateau in Burkina Faso).
West African shea butter is also different from that of East Africa (it may be a variety or a different species than Vittelaria).
Unsaponifiable fraction (non-triglyceride compounds).
The unsaponifiable of shea butter reaches 10% sometimes more.
These are interesting compounds from the pharmacological point of view:
- Phenolic anti-inflammatory and protective substances (catechin),
- triterpenic saponosides (sometimes bitter substances),
- sterols (phytosterols and tocopherol = vitamin E) which are partly responsible for the cosmetic properties of shea butter,
- a small percentage of proteins,
- volatile substances (odoriferous) or terpene solids (waxes).
Recently, Japanese researchers have identified compounds with anticancer and antiviral properties in the defatted part of shea kernels.
They may serve as examples to synthesize new anti-cancer drugs.
SHEA TREE ALMONDS (KERNELS)
VITTELARIA PARADOXA LEAVES
The leaves contain saponosides (which foam a little like soap in the presence of water) and tannins drying the inflamed or infected mucous membranes.
Traditionally a leaf decoction is used in Africa:
- in case of various digestive disorders (stomach pains, diarrhea),
- to treat dermatitis or wounds,
- in gargle (angina, infection of the mouth).
A recent study shows that the shea leaf contains substances that increase the effectiveness of antibiotics (synergistic effect).
One could thus imagine associating an antibiotic treatment internally (amoxicillin for example) with applications of decoction of shea leaves externally on infected wounds to circumvent the bacterial resistances especially those of staphylococcus aureus.
VITTELARIA PARADOXA BARK
Small branch bark is a traditional remedy in Africa.
The bark decoction contains tannins, anti-inflammatory, healing and slightly antibacterial.
This decoction dries up the inflammatory mucous membranes (diarrhea, dysentery, genital infections in women)
SHEA BUTTER AS FOOD
Shea butter has been used as a source of high energy lipids (fat) for a very long time in Africa because:
- the shea tree is a wild plant, resistant and well distributed geographically,
- the extraction of the butter can be done by a simple technique,
Shea butter is a very nutritious fat that is easy to keep and use because it is often quite firm and does not rancid quickly (few unsaturated fatty acids).
Raw shea butter has a rather unpleasant smell and sometimes a bitter taste that disappear once refined.
International agencies fighting against malnutrition in Africa, especially young children, offer dietary lipid supplements that contain a shea butter supplement to improve the firmness of the product and adding dietary linseed oil to provide polyunsaturated fatty acids ( omega 3 and 6) that are missing in shea butter.
Refined shea butter is included in many foods including in Europe but under the term "vegetable fat": chocolate, biscuit, margarine.
It is a fat which is not dietary, for a good balance of food it is necessary to consume also other fatty substances containing more essential fatty acids (fatty fish (sardines, mackerel), peanut oil, corn oil, wheat germ oil ...)
Other endemic African trees have oleaginous fruits or provide shea butter-like fats:
Pentadesma butyracea (Kanya, Lami, butter tree, tallow tree, candle tree, butter tree, tallow tree) present in the humid regions from southern Senegal to Congo.
Dacryodes edulis (safou, atanga, ube, bush pear or plum, nsafu, bush butter tree, butterfruit) present in humid regions from Ivory Coast to Angola and Congo.
SHEA BUTTER FOR SKIN CARE
Shea butter is traditionally used in Africa to beautify skin (and sometimes hair), soothe skin irritations, as a massage balm on muscles or painful joints.
Its soothing, moisturizing and protective properties are recognized and many dermatological preparations now contain shea butter to treat:
- irritated skin,
- dry skin,
- skin that is peeling or presents with keratosis,
- superficial burns such as sunburn,
- and even in case of eczema and atopic dermatitis.
It is possible that the highly refined shea butter loses some of its dermatological properties (anti-inflammatory, soothing, antiseptic) but it remains a fat, moisturizing and well tolerated excipient.
VITELLARIA PARADOXA LEAVES AND BARK
The shea tree is a traditional medicinal plant in Africa, many traditional healers use it to cure common ailments but also for uses a little "magical".
The leaves and bark of vitellaria paradoxa contain compounds with poorly known pharmacological properties.
However the abundance of tannins allows the use of the decoction (leaf or bark) to treat digestive disorders (diarrhea, dysentery), infected wounds or very irritated skin with oozing wounds.
Example for digestive disorders:
A large handful of fresh leaves (300 to 400 g) or 100 to 150 g of dry leaves fragmented in 1 liter of water, decoction for 10 minutes and let cool.
For an adult 1/4 liter (250ml) twice a day.
MANUFACTURE OF SHEA BUTTER
ARTISANAL SHELL BUTTER
It is mainly a collective work reserved to women.
The fruits of shea trees are collected once fallen on the ground (end of wet season), they are freed from the pulp manually or leaving them "to rot".
The almonds are washed and dried, then crushed and sometimes lightly roasted (dry baking) or cooked in water.
After a lot of work we get a fatty paste that is mixed with water.
This mixture is heated until boiling.
The raw butter is collected on the surface of the liquid.
Then this raw butter is improved by mixing and gently heating to remove the water and make it liquid which allows it to be filtered to eliminate some of the impurities.
The technique is simple but long and requires a lot of work (however it is a community work that ensures the cohesion of the group).
The yield is rather low; in general, only half of the fat is recovered.
The rest goes into the meal, which is most often returned to the soil (fertilizer). or serves as fuel.
These are the same techniques (with the same disadvantages) as for other oilseeds or oleaginous kernels:
- By pressing "cold" after crushing, grinding and light heating of the fat cake, the qualities of the butter are good but the yield is average.
- Chemically after crushing, grinding, using a grease solvent, most often hexane, which dissolves the fats and is then evaporated and recycled (good yield).
- Some techniques are a little experimental, eg microwave and preparation of the paste with water and a little hexane (good performance).
VITTELLARIA PARADOXA CULTIVATION
The majority of shea trees are "wild", spontaneous and preserved, kept among other food crops.
In fact, it takes 15 to 20 years to obtain the first shea fruits and 50 years to have a normal harvest, it does not encourage the planting of vittelaria paradoxa (which is mainly made from fresh seeds).
Once installed the shea tree is drought resistant thanks to its well-developed root system but is sensitive to bush fires that can destroy trees in full production in a few minutes.
The burnt tree can regenerate from the stump, but it takes many more years to harvest the first fruit.
Average annual yield: 15 to 40 kg, with good and bad years cyclically.
20 kg of fruit give about 2kg of shea butter.
SHEA TREE and SHEA BUTTER
The shea tree found in African savannahs has edible fruit with an oleaginous kernel.
Shea butter is use as food and as a cosmetic and medicinal product.
The leaves and bark of the tree are used in traditional medicine.
Copyright 2019 : Dr Jean-Michel Hurtel