Kalahari melon oil also known as Tsamma (Damara/Nama), wild watermelon (English), bitterboela, karkoer (Afrikaans), wild watermelon, makatane (Setswana) or Mokaté oil, is a plant oil, extracted from the seeds of the Kalahari melon (Citrullus vulgaris), which is endemic to the Kalahari Desert, spanning Namibia, Botswana and South Africa. Being one of 1,200 varieties of melon, Kalahari melon oil is distinct from regular watermelon seed oil. The seed of the Kalahari melon consists of approximately 50% oil, 35% protein and 5% dietary fibre.
INCI Name
A common misconception is that the INCI name of Kalahari melon oil is different from watermelon oil, that the former is known as Citrullus lanatus seed oil, and the latter Citrullus vulgaris seed oil. For well over 100 years in the scientific literature, both terms have been used interchangeably to describe both the sweet, red watermelon, and the bitter Kalahari melon. The true situation is that the uncertainty regarding the scientific name is recognised by the Personal Care Products Council and the Cosmetics Ingredients and Substances Database of the European Union, who record both INCI names as synonyms of one another.
History
The Kalahari melon is considered the original wild watermelon and the evolutionary ancestor of the common, sweet watermelon, distinguishable by its smaller size, pale yellow flesh and bitter taste. The plant is widely considered to be a weed, where it grows wildly, particularly in Central and Eastern Namibia, Botswana and the North West, Free State, Western Cape and Northern Cape provinces of South Africa.
The Kalahari melon has been used for over 4,000 years by the San people of the Kalahari. The word Kalahari is derived from the Tswana word Kgala, meaning "the great thirst", therefore despite the melon’s bitter taste it has served as a crucial source of water, especially as the water‐rich melons mature in the dry season, when surface water is unavailable. Although the melons were fed on by a wide range of animals, they were used to a greater extent by larger animals as a supplementary water supply. It is said that San can survive for six weeks in the desert on Kalahari melons alone. Additionally, the San would grind the seed into a paste and use it to protect their skin against the harsh deserts elements, while the pulp mixed with water was used as a sunblock. The seed-meal also has a history of use as a cosmetic. After grinding, it was chewed and moistened with saliva, then smeared over the skin for a healthy, blemish-free complexion.
Appearance
Kalahari melon seed oil is liquid at room temperature, naturally light yellow in colour and has a nutty flavour and odour.
Chemistry
Physical properties of Kalahari melon oil
The oil is naturally high in linoleic acid, an omega 6, polyunsaturated essential fatty acid which is critical for cell biology but cannot be made by your body, so it must be supplemented through diet or applied topically to the skin.
Kalahari melon oil is the only oil that contains polyunsaturated fatty acids which are also stable, primarily because it contains vitamin E. The major component is γ-tocopherol (70.56 mg/100 g), followed by α-tocopherol (25.94 mg/100 g). Total tocopherol concentrations up to 2,742.4 mg/kg have been reported in the literature and commercially. These high values provide antioxidant properties and a long shelf life for industrial, pharmaceutical and cosmetic purposes.
Fatty acids present in Kalahari melon oil
Phytosterols are present in the oil, including β-sitosterol (485.49 mg/100 g), campesterol (130.41 mg/100 g) and stigmasterol (25.87 mg/100 g). The phenolic acids present are gallic, protocatechuic, p-hydroxybenzoic, vanillic, caffeic, syringic (trace), p-coumaric, and ferulic acids. These key secondary metabolites exhibit efficient peroxyl-radical scavenging activity and potentially have beneficial pharmacological effects.
Uses
Cold pressed Kalahari melon oil is a newly emerging ingredient, used in a variety of European and American cosmetic and hair-care industries for product development due to its stability, moisturizing and skin conditioning properties. The oil is non-irritant to human skin.
Extraction
The Kalahari melon is a trailing herb of up to long with broad leaves and yellow flowers. The fruit, which varies in size and colour, contains smooth compressed seeds of a black or yellowish white colour. To extract oil from the seeds, the seeds are dried to reduce the water contents. Oil extraction yields vary, depending on the extraction method.