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Monday, February 4, 2013

Shea (Vitellaria paradoxa)

Shea (Vitellaria paradoxa, syn. Butyrospermum paradoxa, Butyrospermum parkii), also know as lulu tree, shi tree, shea-buttertree or vitellaria, is a small to medium-sized (30'-40') tall tree of the Sapotaceae family indigenous to West Africa. The shea fruit (nut) consists of a thin, tart, nutritious pulp that surrounds a relatively large, oil-rich seed from which shea butter is extracted.

Shea nuts on tree in Sudan. Author: Luluworks. Permission: US Federal government - public domain. Source: http://transition.usaid.gov/stories/sudan/successstory_sudan_lulu.html.
Shea Butter

Shea butter is a slightly yellowish or ivory-colored fat extracted from the nut of the African shea tree (Vitellaria paradoxa).[1] Shea butter is a triglyceride (fat) derived mainly from stearic acid and oleic acid. It is widely used in cosmetics as a moisturizer, salve or lotion. Shea butter is edible and is used in food preparation in Africa and also as a prophylactic.[2] Occasionally the chocolate industry uses shea butter mixed with other oils as a substitute for cocoa butter, although the taste is noticeably different.[3][4] The English word "shea" comes from s'í, the tree's name in the Bamana language of Mali.[5] The French name karité comes from ghariti, its [6]

Shea Butter Extraction and Refining

The traditional method of preparing unrefined shea butter consists of the following steps[7]:
  • Separating/cracking: The outer pulp of the fruit is removed. When dry, the nut, which is the source of shea butter, must be separated from the outer shell. This is a social activity, traditionally done by Women Elders and young girls who sit on the ground and break the shells with small rocks.
  • Crushing: To make the shea nuts into butter, they must be crushed. Traditionally, this is done with mortars and pestles. It requires lifting the pestles and grinding the nuts into the mortars to crush the nuts so they can be roasted.
  • Roasting: The crushed nuts are then roasted in huge pots over open, wood fires. The pots must be stirred constantly with wooden paddles so the butter does not burn. The butter is heavy and stirring it is hot, smoky work, done under the sun. This is where the slight, smoky smell of traditional shea butter originates.
  • Grinding: The roasted shea nuts are ground into a smoother paste, water is gradually added and the paste is mixed well by hand.
  • Separating the oils: The paste is kneaded by hand in large basins and water is gradually added to help separate out the butter oils. As they float to the top, the butter oils, which are in a curd state, are removed and excess water squeezed out. The butter oil curds are then melted in large open pots over slow fires. A period of slow boiling will remove any remaining water, by evaporation.
  • Collecting and shaping: The shea butter, which is creamy or golden yellow at this point, is ladled from the top of the pots and put in cool places to harden. Then it is formed into balls.

Industrially, a mechanical sheller such as the Universal Nut Sheller (see video below) 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 in addition to many nonsaponifiable components (substances that cannot be fully converted into soap by treatment with alkali) contains the following fatty acids: oleic acid (40-60%), stearic acid (20-50%), linoleic acid (3-11%), palmitic acid (2-9%). Shea butter melts at body temperature. Proponents of its use for skin care maintain that it absorbs rapidly into the skin, acts as a "refatting" agent, and has good waterbinding properties.[9]

Uses of Shea Butter

Shea butter is mainly used in the cosmetics industry for skin and hair related products (lip gloss, skin moisturizer creams and emulsions, and hair conditioners for dry and brittle hair).[citation needed] 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 some African countries such as Benin, 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.

Benefits of Shea Butter

Some of the possible benefits of topical applications of shea butter include:
  • Evens skin tone
  • Absorbs quickly without leaving greasy residue like mineral oil based products
  • Penetrates deep into the epidermal layer of your skin to help restore elasticity to maturing skin and prevent the cellular breakdown that leads to dry, cracking skin, and stretch marks
  • Stimulates cellular activity, fights the effects of aging and repairs rough, damaged skin
  • Returns natural luster to skin and hair
  • Does not clog pores*Revitalizes, softens and maintains skin moisture
  • Aids in the healing of wounds and may improve scars due to its anti-inflammatory properties
  • Used to heal eczema, burns, rashes, severely dry skin, and to lessen the irritation of psoriasis
  • Moisturizes after shaving to prevent irritation
  • Has natural sun blocking powers and may protect skin from sun damage and environmental elements
  • Nourishes the hair shaft
  • Moisturizes dry, dull over-processed and heat-treated hair resulting in improved brilliance and manageability
  • Helps prevent weak hair from breaking, fading, or thinning out and may promote hair growth

Shea butter is sometimes used as a base for medicinal ointments. Some of the isolated chemical constituents are reported to have anti-inflammatory, emollient and humectant properties.[10] 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.[6]:p.8

In Nigeria shea butter is used for the management of sinusitis and relief of nasal congestion.[11] It is also massaged into joints and other parts of the body where pain is experienced.

Hypersensitivity to Shea Butter

One thing nobody talks about that you need to be mindful of is that shea butter, also known as African Karite butter, contains a natural occurring latex. Although the quantities of latex in shea butter are small, this natural latex is sometimes responsible for causing adverse skin reactions when used by those people who have a latex allergy

The omnipresent shea butter can be found in  soaps, lotions, body butters, hair conditioner, foundation, eye shadow, you-name-it... they're all loaded with the stuff.

This is what the Food Allergy and Anaphylaxis Network (FAAN) which is based in the US says about shea butter:

We suggest you ask your allergist for advice about this. The shea nut is a tree nut that has not been widely used in foods in the past, but shea butter and shea oil are being used increasingly in lotions, bath products, shampoos, and cosmetics. Although no reactions to shea nut have been documented in the medical literature some doctors advise patients with tree nut allergy to use caution and avoid products that contain ingredients derived from the shea nut.”

Shea Butter Contains A Natural Latex

Most people are familiar with latex from the tissue beneath the bark of the rubber tree responsible for the multitude of rubber products. Shea butter contains natural latex. Although it is not exactly the same as the sap-like latex extract from the Rubber Tree (Hevea brasiliensis), it is very similar in chemical composition. Although the quantities of latex in shea butter are small, this natural latex is responsible for the sealing property that shea butter has that may aid in protecting your skin and also contributes to its ability to protect the skin from sun damage.

It should be noted, however, that anyone with a known latex allergy should do a patch test before using. To date, there have been no Shea butter latex allergic reactions reported to the FDA.

Some manufacturers use use a proprietary process to remove the naturally occurring latex, however, trace amounts of the latex may still occur, and if you have a latex allergy you would do best to avoid it all together.

Alternatives to Shea butter include but are not limited to:
  • Mango Butter: Mango butter has emollient properties, thus making it appealing for creams, sun care balms, hair products, and other moisturizing products. 
  • Cocoa butter: Derived from the cacao (Theobroma cacao) bean, also called theobroma oil, is the major ingredient in the commercial manufacture of both white and milk chocolate, as well as some ointments, toiletries, and pharmaceuticals. Aside from the velvety texture and pleasant fragrance, cocoa butter also has emollient (moisturizing) properties and contains natural antioxidants, which have made it a popular ingredient in products for the skin, such as cosmetics, soaps and lotions.
  • Cupuacu Butter: Cupuacu is related to Theobroma cacao. This butter is a little more expensive, but it may well be worth it for those who desire a more moisturizing butter. People who use this alternative for hair care tend to fall in love with it and use it in many mixtures (e.g., whipped butter, conditioner additive, styling agent, etc). Cupuacu butter has the ability to absorb water, thus helping to restore moisture to dry hair. 
  • Lanolin: Also called wool wax or wool grease, is well known for its significant emollient (skin smoothing) action that lasts for hours. Some people are allergic or sensitive to the esters contained in lanolin. New products obtained using complex purification techniques produce lanolin esters in their natural state, removing oxidative and environmental impurities resulting in white, odorless, hypoallergenic lanolin. These ultra-high purity grades of lanolin are ideally suited to the treatment of dermatological disorders such as eczema and on open wounds.[13] 

Latex and Foods

Some people who have latex allergy may also have an allergic response to any of a number of plant products, usually fruits. This is known as the latex-fruit syndrome[14]. Fruits (and nuts/seeds) involved in this syndrome include banana, pineapple, avocado, chestnut, kiwi, mango, passionfruit, strawberry, soy, papaya and chestnuts. Some but not all of these fruits contain a form of latex. The Asthma and Allergy Foundation of America estimates that nearly 6 percent of the United States population have some type of food allergy and up to 4 percent have a latex allergy.[15] It can also cause reactions from foods touched by latex products in the most severe cases.

Some individuals who are highly allergic to latex have had allergic reactions to foods that were handled or prepared by people wearing latex gloves.

Here is a list of cross-reactive foods for people allergic to latex:

Latex cross reactive foods include but are not limited to:
  • Banana
  • Kiwi
  • Papaya
  • Grape
  • Avocado
  • Watermelon
  • Celery
  • Soy
  • Pineapple
  • Mango
  • Passionfruit
  • Strawberry
  • Chestnuts, and
  • less commonly, potatoes, tomatoes, and peaches, plums, cherries, and other pitted fruits

Possible cross reactive foods may include but are not limited to:
  • Spinach
  • Broccoli
  • Apple
  • Squash
  • Legumes
  • Spices, mint, cinnamon

Individual Concerns: Avocados and Latex Allergy

"Like bananas and chestnuts, avocados contain enzymes called chitinases that are associated with the latex-fruit allergy syndrome. There is strong evidence of the cross-reaction between latex and foods that naturally contain high amounts of chitinase enzymes. If you have a latex allergy, you may very likely be allergic to these foods as well. Processing the fruit with ethylene gas increases these enzymes; organic produce not treated with gas will have fewer allergy-causing compounds. In addition, cooking the food may deactivate the enzymes."
Source: http://www.whfoods.com/genpage.php?tname=foodspice&dbid=5#safetyissues Accessed19 January 2013.

Another surprising fact is that many manufacturers continue to handle all their food products with latex gloves in the factory, which can deposit hidden latex directly onto the food itself. 

ALLERGY ALERT: Shea is sourced from the fruit (nut) of a tree that is closely related to the rubber tree, which yields latex, a common allergen. If you have a latex allergy, you're likely to become allergic to shea, as shea contains a natural latex. Although it is not exactly the same as the sap-like latex extract from the Rubber Tree (Hevea brasiliensis), it is very similar in chemical composition. Although the quantities of latex in shea butter are small, this natural latex is responsible for the sealing property that shea butter has that may aid in protecting your skin and preventing sun allergies.

Persons suffering from latex allergies should do an allergy Patch Test (contact allergy testing) before using any shea butter product. Many people with latex allergies are not affected by shea butter, but some are, so it is better to be safe than sorry.

It is important to note that latex sensitization (a similar condition to latex allergy) worsens with cumulative exposures to latex and chemically similar products. Individuals who become severely sensitized can progress beyond contact dermatitis, developing many food allergies and even suffering anaphylactic shock upon exposure.

If you have a known latex allergy or sensitization, check the labels on all your personal care products and avoid anything containing shea butter, often listed on the label as Butyrospermum parkii. Promptly toss these products. Your skin will thank you for it.

Classification

The United States Agency for International Development, Gassel Consulting, and many other companies[12] 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[citation needed] 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. 

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. 17: SHEA  http://books.nap.edu/openbook.php?record_id=11763&page=303  
3. Reinforcing sound management through trade: shea tree products in Africa.  http://www.fao.org/docrep/008/y5918e/y5918e11.htm 
4. Fold, N. 2000. A matter of good taste? Quality and the construction of standards for chocolate in the European Union. Cahiers d’Economie et Sociologie Rurales, 55/56: 92–110 http://www.inra.fr/sae2/publications/cahiers/pdf/fold.pdf  
5. Shea. "Reference.com Dictionary Entry".
6. Goreja, W. G. (2004). Shea butter: The nourishing properties of Africa's best kept natural beauty secret.. Shea Butter: The Nourishing Properties of Africa's Best-Kept Natural Beauty Secret. TNC International. p. 5. ISBN 9780974296258. 
7. Experimental study of Shea butter extraction efficiency using a centrifugal process. http://www.arpnjournals.com/jeas/research_papers/rp_2009/jeas_0809_221.pdf 
8. 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. 
9. Hemat, R. A. S. (2003). Shea butter: Principles of Orthomolecularism. Urotext. p. 160. ISBN 9781903737057. 
10. 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. 
11. 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. 
12. A marketing Manual for West Africa: Buying and Selling Shea Butter. http://www.gasselconsult.net/shea/sheadocs/Buying%20and%20Selling%20Shea%20Butter%20Fintrac.pdf 
13. Arden Jones MR, Steel I, Powell SM (July 2002). British Journal of Dermatology 147 (Suppl 62): 71. (2002), British Contact Dermatitis Group: Summaries of Papers. British Journal of Dermatology, 147: 67–74. doi: 10.1046/j.1365-2133.147.s62.19.x. 
14. Brehler R, Theissen U, Mohr C, Luger T (April 1997). ""Latex-fruit syndrome": frequency of cross-reacting IgE antibodies". Allergy 52 (4): 404–10. doi:10.1111/j.1398-9995.1997.tb01019.x. PMID 9188921.   
15. "Latex allergy". Better Health Channel.


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