Shea butter, women's gold
Shea butter is an edible vegetable oil extracted from the fruit of the shea tree, which grows mainly in the wooded savannahs of West and Central Africa. The name ghariti means "butter tree" in Wolof from Senegal, and is the origin of the French name "karité".
Shea butter is mainly used in cooking in Africa and in the chocolate industry in Europe (as a substitute for cocoa butter). It is also known in Africa, Europe and the United States for its skin-softening and nourishing cosmetic properties, which make it an ingredient in many cosmetics and pharmaceutical products.
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Both the harvesting of the fruit and the extraction and local marketing of the shea nut are mainly carried out by African women in rural areas, hence its nickname of "women's gold" (even though the international shea industry is essentially dominated by men).
Once the fruit has been harvested (June-September), the pulp is removed to produce a nut, which is then dried. The kernel is then recovered by crushing the nuts. It is then washed and left to dry in its intact shell, to avoid acidification (increase in free fatty acids) due to the action of microorganisms. Properly prepared, almonds can be stored for up to a year without deterioration.
Harvesting the fruit and preparing the almonds requires one hour's work per kilo of dry almonds.
The almonds are then crushed, roasted and ground into a thick paste. After processing, three kilos of almonds yield around one kilo of butter.
There are three methods for extracting butter from the shea kernel.
The traditional method
The thick paste obtained is mixed with water and vigorously churned. The resulting paste is stirred with long spatulas, while the mixture is heated.
Immersion in boiling water separates the butter from the other components of the almond, notably the impurities that settle to the bottom of the container. Once removed, the butter floating on the surface is kneaded before being cooked for a long time to allow the water to evaporate and the impurities to settle.
The oil (in fact, the liquid butter) thus obtained is filtered before being packaged. The result is artisanal shea butter. Although it is often said that heat somewhat alters the qualities of artisanal shea butter, only comparative physico-chemical analysis can tell for sure.
It is highly likely that this statement justifies industrial shea production to the detriment of African women[ref. needed]. African women, who have the know-how to extract shea in an environmentally-friendly way, provided they work in dignified and healthy conditions.
Any impurities remaining at the bottom are collected to form balls, which are used as fuel to heat new pots.
The result is 30-35% butter per dry weight of nuts.
Cold press extraction
The term "cold extraction" is misleading. It is an industrial extraction method by refining presented by the cosmetics industry as cold extraction and relayed by influencers from 2018. The aim is to meet the growing demand for natural shea butter.
The "cold" extraction stages are as follows:
- degumming: remove waxes and mucilages by injecting steam into the oil, which is heated to around 70°C. The aim is to eliminate certain components suspended in the oil;
- decolorization: pigments and chlorophyll are removed by filtering the oil through activated carbon. The oil is heated to between 90 and 120°C and the necessary quantity of Fuller's earth is absorbed. Once the action is complete, the bleaching agent is separated from the oil by the classic method of filtration;
- deodorization: to extract the volatile products responsible for taste and odor. Dry steam, at around 140°C, is sent into the oil, which is heated to 180°C under vacuum.
- winterization or demargarinization (not mandatory): the oil is cooled to between 3° and 8° for several hours.
This extraction method is still more virtuous than the solvent extraction method.
Solvent extraction
Almonds are crushed industrially and then a solvent, hexane, is used. The butter still contained in the kernels dissolves in the hexane. The hexane is then allowed to evaporate and the shea butter is recovered. This method is the most cost-effective, but the resulting shea butter is of inferior quality.
The result is up to 45% butter per dry weight of nut.
Composition
In its natural state (virgin, raw, first cold-pressed), without any processing, shea butter contains five main fatty acids (triacylglycerides): palmitic acid, stearic acid, oleic acid, linoleic acid, and arachidic acid. Among these, stearic and oleic acids make up about 85 to 90%, depending on the origin.
- Oleic Acid (40-60%)
- Stearic Acid (20-50%)
- Linoleic Acid (3-11%)
- Palmitic Acid (2-9%)
- Linoleic Acid (< 1%)
- Arachidic Acid (< 1%)
The relative proportion of stearic and oleic acids influences the consistency of the butter. Stearic acid provides a solid consistency, while oleic acid gives a soft or even liquid consistency. Thus, shea butter from the Mossi plateau (Burkina Faso) and northern Ghana has a higher stearic acid content and is generally harder; shea butter from Uganda is liquid and requires fractionation to become butter; shea butters from West Africa vary more in their consistency.
In addition to its fatty acids, shea butter contains catechins, vitamins E, A, essential fatty acids, and triterpenes.
Sarah Traboulsi