Shea butter

Shea butter is a slightly yellowish or ivory-colored fat extracted from the nut of the African shea tree (Vitellaria paradoxa).[1] It is widely used in cosmetics as a moisturizer, salve or lotion. Shea butter is edible and may be used in food preparation.[2] Occasionally the chocolate industry uses shea butter as a substitute for cocoa butter, although the taste is different.[3]

The English word "shea" comes from s'í, the tree's name in the Bamana language of Mali. The French name karité comes from ghariti, its equivalent in the Wolof language of Senegal.

Contents

Butter extraction and refining

The traditional method of preparing unrefined shea butter consists of the following steps:

Industrially, a mechanical sheller such as the Universal Nut Sheller may be used, although controversy over its usability with shea nuts is reported in that article. The refined butter may be extracted with chemicals such as hexane, or by clay filtering.

Composition and properties

Shea butter extract is a complex fat that contains, besides many nonsaponifiable components (substances that cannot be fully converted into soap by treatment with alkali), the following fatty acids:oleic acid (40-60%), stearic acid (20-50%), linoleic acid (3-11%), palmitic acid (2-9%), linolenic acid(<1%) and arachidic acid(<1%).[4]

Shea butter melts at body temperature and absorbs rapidly into the skin without leaving a greasy feeling.

Uses

Shea butter is mainly used as an ingredient in chocolate.[3] Shea butter is also in cosmetics, such as moisturizer creams and emulsion, and hair conditioners for dry and brittle hair. It is also used by soap makers, typically in small amounts (5-7% of the oils in the recipe), because of its property of leaving a small amount of oil in the soap.

In Africa, shea butter is used for cooking oil, as a waterproofing wax, for hairdressing, for candle-making, and also as an ingredient in medicinal ointments. It is also used by makers of traditional African percussion instruments to increase the durability of wood (such as carved djembe shells), dried calabash gourds, and leather tuning straps.

Medicinal

Shea butter is used as a base for medicinal ointments. Some of the isolated chemical constituents are reported to have anti-inflammatory, emollient and humectant properties.[5] Shea butter has been used as a sunblocking lotion and has a limited capacity to absorb ultraviolet radiation. [3]

In Ghana, shea butter, locally known as nkuto (Akan) or nku (Ga) is used as lotion to protect the skin during the dry Harmattan season.

In Nigeria shea butter is used for the management of sinusitis and relief of nasal congestion.[6] It is also massaged into joints and other parts of the body where pain is experienced.

Classification

Some companies have suggested a classification system for shea butter separating it into five grades: A (raw or unrefined, extracted using water), B (refined), C (highly refined and extracted with solvents such as hexane), D (lowest uncontaminated grade), E (with contaminants). Commercial grades are A, B, C. The color of raw (grade A) butter ranges from cream (like whipped butter) to grayish yellow, and it has a nutty aroma which is removed in the other grades. Grade C is pure white While the level of vitamin content can be affected by refining, up to 95% of vitamin content can remain in refined grades (i.e. grade C) of shea butter while reducing contamination levels to non-detectable levels.

See also

References

  1. ^ Alfred Thomas (2002). "Fats and Fatty Oils". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a10_173. 
  2. ^ http://books.nap.edu/openbook.php?record_id=11763&page=303
  3. ^ a b c http://www.fao.org/docrep/008/y5918e/y5918e11.htm
  4. ^ Davrieux, F., Allal, F., Piombo, G., Kelly, B., Okulo, J.B., Thiam, M., Diallo, O.B. & Bouvet, J.-M. (2010) Near Infrared Spectroscopy for High-Throughput Characterization of Shea Tree (Vitellaria paradoxa) Nut Fat Profiles. Journal of Agricultural and Food Chemistry, 58, 7811-7819.
  5. ^ Akihisa, T; Kojima, N; Kikuchi, T; Yasukawa, K; Tokuda, H; t Masters, E; Manosroi, A; Manosroi, J (2010). "Anti-inflammatory and chemopreventive effects of triterpene cinnamates and acetates from shea fat". Journal of oleo science 59 (6): 273–80. PMID 20484832. 
  6. ^ Tella, A, Br (1979). "Preliminary studies on nasal decongestant activity from the seed of the shea butter tree, Butyrospermum parkii". J Clin Pharmacol 7 (5): 495–497. 

External links