Kalahari Melon Oil

Botanical: Citrullus lanatus
Family: Cucurbitaceae
Vernacular: Tsamma melon, Wild watermelon, Kalahari melon

Description

The Kalahari melon is the biological ancestor of the watermelon, now found all over the world, but which originated in the Kalahari region of Southern Africa. It is thought that as continental drift split Gondwanaland, the Cucurbitaceae family (gourd) was also split, generating different varieties across the latitudes. Unlike the common watermelon, whose flesh is sweet and red, the Kalahari melon’s juicy flesh is pale yellow or green, and tastes bitter. A creeping annual herb, the Kalahari melon has hairy stems, forked tendrils and three-lobed hairy leaves. Its flowers are bright yellow. 

Fruit

Fruits vary significantly, from small and round in the wild, to larger and more oblong-shaped under cultivation. The surface is smooth, pale green with irregular bands of mottled darker green radiating from the stalk. The flesh is a pale green or yellow, and contains numerous brown seeds. In its wild form, the fruit is bitter to bland in taste, and largely inedible when fresh.  Many varieties are grown for their oil and protein rich seeds.

Distribution

Citrullus lanatus species are highly adapted to surviving drought and high light stress conditions, despite carrying out normal C3-type photosynthesis. They are therefore adapted to desert habitats, and are found all over Southern Africa, though the Kalahari melon is most closely associated with the Kalahari sands of Namibia, Botswana, south-western Zambia and western Zimbabwe.

Traditional uses

Traditionally, a crucial water-source in the Kalahari, the Kalahari melon has also been consumed as a food, despite its bitterness. Before the arrival of modern day transport, travel across the Kalahari desert was constrained by the Kalahari melon season, as the fruit supplied both food and water to the traveller. The Kalahari bushman is highly dependent upon the melon; it is possible to survive in the desert for 6 weeks on Kalahari melon alone. To extract the water, the top of the melon is lopped off, the central pulp is then scraped out and eaten raw, leaving a cavity.  The remaining pulp is then mashed up, using a stick inserted into the cavity, to produce a watery mixture that is both eaten and drunk.  Or, a stew can be cooked in the rind itself, by adding meat and other vegetables to the chopped up melon flesh and placing the ‘cooking pot’ melon rind on the embers of the fire.  The rind can then be used to make pickles.  Throughout these processes the seeds are safely kept aside, since they are highly prized both as a protein-rich snack food and for their oil content.  The seeds are rich in a clear, yellow oil which has a long history of use as a cosmetic.  Traditionally, used as a moisturizer to protect the skin from the sun, to ensure a blemish-free complexion, to promote hair growth and in soaps.   Modern local entrepreneurs have developed effective and popular skin lotions and tonics building on this traditional heritage. 

Known properties

The primary area of interest for the Kalahari melon is in the properties of it’s seeds.  Comprising 50% oil to 35% protein, the seeds have both nutritional and cosmetic importance.  The seeds contain vitamin C, B2 and G, minerals, riboflavin, fat, carbohydrates and protein.  The absence of hydrocyanic acid also renders them an excellent livestock feed. The seeds are as rich in oil as the conventionally used cottonseed, soy and corns and in West Africa there is a sizeable industry in the production of seeds from a related melon (commonly known as the Egusi melon), with annual production figures in the range of 250-300,000 tonnes of seed.  The oil predominantly contains unsaturated fatty acids, is rich in essential fatty acids, cholesterol free, containing linloleic- oleic- palmitic fatty acids.  There is a high activity of detoxifying hydroxyl radicals (antioxidants) possibly aiding the herb’s survival in the extraordinarily harsh Kalahari desert environment. Combined, these characteristics make the Kalahari melon seed oil particularly interesting to the cosmetic industry where it is used by a number of prominent European cosmetics companies for moisturizing, regenerating and restructuring skin-care formulations.

Technical Specifications

INCI name:	Citrallus lanatus (Kalahari Melon) Seed Oil
CAS No:	90063-94-8
EINECS No:	290-054-3
Description:	Yellow coloured oil, which is liquid at room temperature
Specific gravity:	0.91-0.92
Iodine value gI2/100g:	120-130.
Saponification value mgKOH/g:	180-200
Acid value mg KOH/g:	5max
Peroxide value mEq O2/Kg:	15max

Fatty acid composition

Parameter	Range
16:0 palmitic %	7.0-13.0
18:0 stearic %	5.0-11.0
18:1 oleic %	10.0-24.0
18:2 linoleic %	55.0-70.0
18:3 -linolenic %	Max 0.5
minor components %	Max 0.1

 

MANUFACTURING PROCESS :	Cold pressed (T<60°C) - no solvents or chemicals used.
	Successive filtrations of the oil through filter cloth.
STORAGE :	-keep away from light, heat (T<20°C) and in a dry place. Sparge with Nitrogen.
PACKAGING :	200 kg metal drums

Actives

Linoleic acid an essential fatty acid

Applications

Skin-care - moisturising, restructuring, regenerating

Hair-care - conditioning

Soap

Suggested References

Akashi, K. et al (2004) Potent hydroxyl radical-scavenging activity of drought-induced type-2 metallothionein in wild watermelon. Biochem Biophys Res Commun. 2004 Oct 8: 323(1):72-8.

Jacks, T. J. et al (1972) Cucurbit Seeds: I. Characterizations and Uses of Oils and Proteins.  A Review. Economic Botany, 26 (2): 135-141.

Lazos, E. S. (1986) Nutritional, Fatty acid, and Oil Characteristics of Pumpkin and Melon Seeds. Journal of Food Science, 51 (5): 1382.

Maggs, G. I.  (1996) Agricultural potential of indigenous Cucurbitaceae in Namibia, National Botanical Research Institute of Namibia (NBRI).

Renew, A. (1968) Some edible wilds cucumbers (Cucurbitaceae) of Botswana. Botswana Notes and Records, 1: 5-8.

Rûgheimer, S. (1996) Cucurbitaceae: potential new crops for arid lands. MSc Thesis, University of Stellenbosch, South Africa.

Rûgheimer, S. (1997) Chemical characterization of the oil extracted from Citrullus lanatus seeds. University of Stellenbosch, South Africa.

SEPASAL (2004) Citrullus lanatus (Thunb.) Matsum. & Nakai, Lagenaria siceraria (Molina) Standl., Kew Gardens, http://www.kew.org/ceb/sepasal/internet/. 01/06/04.

Van der Vossen, H. et al (2004) Citrullus Lanatus (Thunb.) Matsum. & Nakai. In Plant Resources of Tropical Africa 2. Vegetables (Eds, Grubben, G. and Denton, O.), Backhuys, Leiden, Netherlands, PROTA Foundation, Wageningen, the Netherlands, pp. 36-40.