Shea butter (karite): Nutrition and bioactive compounds
Shea butter, also known as karite, is a supreme product originating from the relatively narrow area in Africa. It is a principal compound of many highly regarded cosmetic products due to the skin moisturising and anti-irritation properties. In the producing African countries, however, the butter is generally used for cooking.
The butter is a fat extracted from the nut of the African shea tree (Vitellaria paradoxa) which grows in savanna from the Eastern Senegal to Ethiopia (1–4). V. paradoxa has two subspecies with distinct geographical ranges: V. paradoxa paradoxa grows between Senegal and Nigeria, mostly at lower elevations (100–600 m), while V. paradoxanilotica resides in Sudan, Ethiopia, and Uganda territories at the elevation from 650 to 1600 m (1).
Nutrition and bioactive compounds
Lipids are predominant constituent of the shea kernels and butter. Its fat is characterized by 16 saturated and unsaturated fatty acids, with the five (oleic, stearic, palmitic, linoleic, and arachidic) prevailing ones (2). The variability among kernels of different origin is quite high because the chemical composition depends on many parameters: environmental influences, geographical location, agronomic factors, and genetic variation (2,5). In general, fat content of shea kernels should be higher in high altitudes and cooler environment (20–25°C) (2).
Chemical properties of shea butter vary across its distribution range: the highest oleic acid content was found in Uganda (57%), and the lowest in Burkina Faso (45%), while the proportion of stearic acid was highest in the shea butter from the Mossi plateau in Burkina Faso (45%) and lowest in Uganda butter (31%)(3).
Shea butter has been reported to have a pale yellow, cream or grey colour (4). It is predominantly composed of triglycerides and a high proportion of unsaponifiable matter, mainly consisting of triterpene alcohols (60–70%). That’s the reason the skin care products with the shea butter have good penetrative properties (3).
Shea butter has high levels of tocopherol and contains some polyphenols, which are all known antioxidants (2,4). Especially important is α-tocopherol (form of vitamin E): its content in the butter varies considerably among regions. It has been reported in the range from 29 mg /100 g in Uganda to 800 mg /100 g in the West African shea butter (2,4). Additionally, the butter contains allantoin, which is known for the anti-inflammatory and healing effect on the skin (3).
Cultivation
Shea tree is indigenous to the savanna belt of sub-Saharan Africa (500–700 km wide), extending through 19 countries across the continent (2,3). It mostly grows in the semi-arid to arid areas north of the humid forest zone, and reaches 15–22 m in hight (2). The shea tree begins to bear fruit only after about 15 years, yet it can produce the good-quality fruits with a high fat content for up to 30 years (2).
Seed propagation is used for cultivation as vegetative propagation is still problematic, but grafting can accelerate the fruiting (3). Trees’ distribution depends on the cropping system: recommendations vary from 25 to 100 trees per ha (3). The fruits are produced from May to August (2). They weight from 10 to 57 g, resulting in annual production from 15 to 30 kg per tree (2).
Shea is beneficial to the overall resilience of the ecosystem, maintaining soil fertility and biodiversity of flora and fauna. Although it is affected by the climate variability and change, it is quite a resistant crop (7).
Uses
Shea butter is a very popular ingredient in cosmetics, especially in the Western world, and is thus highly demanded by the international cosmetic industries. It is also a suitable base for topical medicines and has been traditionally used to relieve inflammation of the nostrils (3). Shea butter has become popular also in the European and Japanese cuisine as well as the potential replacement of a cocoa butter in the chocolate manufacture (2).
In the origin countries, shea butter is mainly used for cooking. The pulp of the shea fruit is sweet and nutritious, and an important food source at the beginning of the rainy season in sub-Saharan Africa (2). It has also been studied as an animal feed supplement (8).
Waste water from the shea butter production has pesticidal properties (3) The press cake and the husks are also potential fertilizers and fuels (3). Shea tree is an important source of honey (3). Leaves, flowers, bark and latex are all being used for various purposes (3).
All its beneficial properties aside, shea production is very important in many producing countries because it helps to reduce poverty through exports and increases food security (4,7), enabling local people a better quality of life.
Sources:
1. Nafan D., Noel D.D., Martial Y.S.D. (2021): Estimation of shea trees (Vitellaria paradoxa C.F. GAERTN.) fruit production by assessing the correlation between yield parameters and dendrometric features in northern of CÔTE D’IVOIRE. Journal of Experimental Biology and Agricultural Sciences 9(6): 745–758.
2. Honfo F.G., Akissoe N., Linnemann A.R., Soumanou M., Van Boekel M.A.J.S. (2014): Nutritional Composition of Shea Products and Chemical Properties of Shea Butter: A Review. Critical Reviews in Food Science and Nutrition, 54:673–686; DOI: 10.1080/10408398.2011.604142
3. Plant Resources of Tropical Africa: https://www.prota4u.org/database/protav8.asp?g=psk&p=Vitellaria paradoxa
4. Omujal F. (2009): Post harvesting handling practices and physico-chemical characteristics of shea (Vitellaria paradoxa) fruit in Uganda. Dissertation, Makerere University.
5. Goumbri B.W.F., da Silva T.L.T.,· Marini R.D., Semdé R., Somé T.I., Danthine s. (2021): African Shea Butter Properties Related to Common Extraction Technologies: A Review. Food and Bioprocess Technology (on-line); https://doi.org/10.1007/s11947-021-02708-w
6. Enweremadu C.C., Alamu O.J. (2010): Development and characterization of biodiesel from shea nut butter. Int. Agrophysics 24: 29–34.
7. Venturini S., Haworth A., Coudel N., Jiménez Alonso E., Simonet C. (2016): Cultivating Climate Resilience: The Shea Value Chain. BRACED Knowledge Manager collection Cambio Climático y Cadenas.
8. Donkor M.N., Mosobil R., Abaah E.A., Kanati C., Akabanda F., Donkor A.M. (2021): Potential of shea fruit-based ingredients for the feed industry. Agric. & Food Secur. 10: 54; https://doi.org/10.1186/s40066-021-00326-5
