Mongongo oil has been valued for centuries in Africa and is now
gaining popularity in the rest of the world as we become educated about
its beneficial qualities. Not only is the fruit extremely nutritious,
but the oil has many useful properties as an emollient for both hair and
skin. What makes mongongo different from other botanical oils and how
does this affect its properties?
Origin
Mongongo oil is obtained by cold-pressing the nuts that come from the
Mongongo or Manketti tree (Schinziophyton rautanenii). The Manketti
tree is found from coast to coast in Southern Africa. It thrives in the
seasonal dry lands where it weathers a broad range of temperatures from
sub-freezing to scorching desert heat. It is found both sporadically
scattered and also in large groves throughout northern Namibia, southern
Angola, Zambia, Botswana, Zimbabwe, Mozambique and Malawi. The
egg-shaped, reddish brown fruit is prized by both the people and the
elephants indigenous to the region. The nuts are often gathered from
elephant dung, a practice that is less labor intensive than harvesting
the fruit and extracting the nut from the center.
Composition of Mongongo Oil
The nut is very high in fat (>57%) and contains a plethora of
other valuable nutrients, such as calcium, magnesium, iron, copper, zinc
and thiamine. Each seed contains approximately 560 mg of vitamin E
(tocopherol). The antioxidant properties of this vitamin lend a high
degree of thermal and oxidative stability to the oil, which greatly
delays onset of rancidity of the oil, even in the intense South African
heat. The oil has been greatly prized, not only for its nutritive
benefits, but also as a skin and hair emollient and skin protectant.
The composition of the oil in mongongo fruit is fairly different from
many other plant oils used as topical hair treatments or conditioning
ingredients. It is comprised of between 40-50% polyunsaturated fatty
acids, as compared to shea and coconut oil, which are comprised largely
of saturated fatty acids and mango, olive, avocado, jojoba and almond
oils, which are comprised mainly of monounsaturated oils.
Fatty Acid Content of Mongongo Oil:
- 45-55% polyunsaturated fatty acids: linoleic acid, alpha-eleostearic acid
- 17% saturated fatty acids: palmitic acid, stearic acid
- 18% monounsaturated fatty acid: oleic acid
Unsaturated molecules have at least one carbon-carbon double bond in
their structure. Double bonds are connected at a different angle than
single ones and this produces a kink in the molecular geometry. This
type of structure inhibits crystallization by impeding packing of
adjacent molecules. For this reason, oils with high concentrations of
polyunsaturated and monounsaturated fatty acids are typically either
liquids at room temperature or melt readily upon contact with skin.
Stearic acid, a saturated hydrocarbon molecule with 18 carbons
(relatively long-chain fatty acid) has a melting point of 69.6°C
(157.28°F). Oleic acid is a monounsaturated hydrocarbon with a melting
point of 10.5°C (50.9°F). Polyunsaturated acids, such as linoleic and
linolenic, have multiple kinks in their chains and are liquid at very
low temperatures (melt point = -5°C (23°F) for linoleic acid).
The protective outer cuticle layer of hair is not a solid surface,
but is porous in order to allow transport of oils and water back and
forth through the hair and into the cortex. The lipid-rich cell membrane
complex layer just beneath the cuticle scales acts as a diffusion port,
enabling fatty acids and moisture to travel into the interior of the
hair strand.
Molecular size and shape determine the probability of a fatty acid to
travel through the cuticle layer into the cortex of the hair. Saturated
fatty acids such as stearic acid, lauric acid and palmitic acid diffuse
easily through the pores of the cuticle layer and penetrate the cortex,
where they provide flexibility and suppleness to hair strands.
Spectroscopic studies demonstrate that despite their kinked structure
due to the single double bond, monounsaturated fatty acids are also able
to readily penetrate the interior of the hair via this route.
However, the more unwieldy structure of polyunsaturated fatty acids
prohibits them from penetrating into the interior of the hair strand and
they remain adsorbed onto the surface of the hair. Oils such as
mongongo oil that are high in polyunsaturated fatty acids, form a
protective and emollient film on the surface of the hair, where they act
as a barrier preventing moisture from escaping the interior of the
hair. These fatty acids can add gloss to hair and improve comb-ability
by smoothing the surface of the hair. Due to the presence of the acid
groups in their structure, these ingredients can also have a mild
humectant effect.
hair, and stearic acid, palmitic acid and oleic acid are good at
penetrating to the cortex to supply elasticity and improved mechanical
properties. Perhaps the most interesting properties of mongongo oil can
be attributed to the presence of α-eleostearic acid, a conjugated
trienoic fatty acid. This molecule has three double bonds in the middle
of its structure that are conjugated, meaning they alternate (double
bond-single bond-double bond-single bond…). These types of structures
have unique chemical properties due to this conjugation, as they can
delocalize certain of their electrons in response to various stimuli in a
process known as resonance stabilization.
There are three reasons that this very specific feature of the
organic structure of α-eleostearic acid is interesting to us in hair
care applications. The first is that the conjugated diene structure
enables this fatty acid to act as a mild sun protective agent via
UV-absorption and subsequent resonance stabilization. The second reason
is that the molecule is capable of undergoing a UV-initiated
photopolymerization reaction, whereby the fatty acids molecules link
together into a three-dimensional crosslinked network, forming a
flexible film on the surface of the hair. This provides physical
protection to the hair and also may impart style hold or curl retention.
Thirdly, this polymerization mechanism (called curing) substantially
reduces drying time for hair. Even once polymerized, the carboxylic acid
groups on the molecule should be sufficient enough “hydrophilic
handles” to permit removability in water, especially if conditioner
and/or mild shampoo are used.
Since it is fun to experiment with our hair, it seems worthwhile to
at least sample some of these new products containing this ingredient.
Look for products that contain other quality ingredients and that
feature mongongo oil sufficiently high up the ingredient list. Beware
products that are comprised primarily of other oils and only include
this as a trace ingredient as they may prove to not be a sound
investment. Let us know your thoughts when you do try some of the new
mongongo oil products.
- Dyer, J.M., et al, http://naldc.nal.usda.gov/download/22993/PDF, Differential Extraction of Eleostearic Acid-Rich Lipid–Protein Complexes in Tung Seeds, JAOCS, Vol. 75, no. 11 (1998)
- Yang et al. BMC Plant Biology 2010, 10:250, http://www.biomedcentral.com/1471-2229/10/250
