Shea Butter Scientific Information
Shea butter is the fat extracted from the kernels
of Vitellaria paradoxa Gaertner (Sapotaceae), which is also
known as Butyrospermum parkii. The species is found across
19 countries across the African savanna zone from Senegal to Ethiopia.
Shea butter contains high levels of UV-B absorbing triterpene esters,
including cinnamic acid, tocopherols (vitamin A), and phytosterols.
Shea butter does contain a high percentage of unsaponifiables, such
as phytosterols (campesterol, stigmasterol, beta-sitosterol , and
alpha-spinosterol) and triterpenes (cinnamic acid esters, alpha-
and beta-amyrin, parkeol, buytospermol, and lupeol), and hydrocarbons
such as karitene (1, 2)
Shea Butter Fatty Acid Profiles
Shea butter is composed of five principal fatty acids:
palmitic, stearic, oleic, linoleic, and arachidic (Table 1) (3).
The fatty acid composition is dominated by stearic and oleic acids,
which together account for 85-90% of the fatty acids (3). The relative
proportions of these two fatty acids produces differences in shea
butter consistency. The high stearic acid content gives the shea
butter its solid consistency, while the percentage of oleic acid
influences how soft or hard the shea butter is.
The proportions of stearic and oleic acids in the
shea kernels and butter differ across the distribution range of
the species. Ugandan shea butter has consistently high oleic acid
content, and is liquid at warm ambient temperatures. Ugandan shea
butter fractionizes into liquid and solid phases, and is the source
of liquid shea oil. The fatty acid proportion of West African shea
butter is much more variable than Ugandan shea butter; the oleic
content ranges from 37 to 55%. Variability can even be high in relatively
small local populations; a tree that produces hard butter can be
located right next to one that produces soft butter. Nuts are gathered
from a wide area for local production, so shea butter consistency
is determined by the average fatty acid profile of the population.
Within West Africa, shea butter from the Mossi plateau region of
Burkina Faso has higher average stearic acid content, and was found
to be harder than shea butter from other West African regions (3).
| Table
1. Fatty acid variation in shea butter (3) |
| Fatty
acid |
Percentage of total fatty acids
|
|
Mean
|
Min
|
Max
|
| 16:0 |
Palmitic |
4.0
|
2.6
|
8.4
|
| 18:0 |
Stearic |
41.5
|
25.6
|
50.2
|
| 18:1 |
Oleic |
46.4
|
37.1
|
62.1
|
| 18:2 |
Linoleic |
6.6
|
0.6
|
10.8
|
| 20:0 |
Arachidic |
1.3
|
0.0
|
3.5
|
|
Fatty
acid carbon chain lenth:number of double bonds
N.B. Data are from 432 trees samples in 42 populations in
10 countries (3)
|
Shea Butter Phenolics
Phenolic compounds are known to have antioxidant
properties. A recent study characterized and quantified the most
important phenolic compounds in shea butter (4). This study identified
10 phenolic compounds in shea butter, eight of which are catechins,
a family of compounds being studied for their antioxidant properties.
The phenolic profile is similar to that of green tea, and the total
phenolic content of shea butter is comparable to virgin olive oil.
Also, this study was performed on shea butter that had been extracted
with hexane, and the authors note that alternative extraction methods
- such as traditional extraction - may result in higher phenolic
levels. Furthermore, they note that the catechin content alone of
shea kernels is higher than the total phenolic content of ripe olives.
This study also found that the overall concentration
and relative percentages of different phenolic content in shea kernels
varied from region to region. The authors hypothesized that the
overall concentration of phenols in shea kernels is linked to the
level of environmental stress that the trees endure.
Sources:
1. Wiesman, Z, S. Marans, G..Bianchi, and J Bisgaard.
2003. Chemical analysis of fruits of Vitellaria paradoxa. In Teklehaimanot,
Z (Ed) Improved Management of Agrofrestry Parkland Systems in Sub-Saharan
Africa, Final Report. School of Agricultural and Forest Sciences,
University of Wales: Bangor, U.K.; pp131-139.
2. Badifu, G.I.O. 1989. Lipid composition of Nigerian
Butyrospermum paradoxum kernel. J Food Compos Anal 2:238-244.
3. Maranz, S, Z. Wiesman, J. Bisgaard and G. Bianchi.
2004. Germplasm resources of Vitellaria paradoxa based on variations
in fat composition across the species distribution range. Agroforestry
Systems 60:71-76.
4. Maranz, S., Z. Wiesman and N. Garti. 2003. Phenolic
constituents of shea (Vitellaria paradoxa) kernels. J Agric Food
Chem 51: 6268-6273.
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