The search for alternative cooking oils is particularly important as economies expand and seek ways to improve diet. Whilst the generation of biodiesel has moved growers away from conventional seed oil production such as sunflower and palm oils, so new sources are continually sought. One plant, the Bitter Apple (Citrullus colocynthis L.) might provide a solution with its unique oil bearing seeds. It’s seeds are also cited as a potential biodiesel source (Giwa et al., 2010).
Citrullus colocynthis L., (Family: Curcurbitaceae) commonly called the Bitter Apple, Bitter Gourd, Egusi Melon or Handhal was from biblical times gathered for its medicinal properties. Indeed it is probably referred to in the Bible. It was a traditional Persian medicine for highly effective pain relief, especially for neuralgia. It is cultivated in both the tropical and arid or semi-desert regions of Africa and the Middle East. Its pulp and its seeds are a food and is a crop inter-planted with maize, cassava and yam (Uruakpa et al., 2004).
The fruit itself is round, yellow with a thin but hard rind. The fruit pulp is extremely bitter and can cause intestinal haemorrhage when ingested. The pulp is still used as a laxative because it contains some potent glucosides, most notably colocynthin (Dane et al., 2007). The gourd also yields distinctive seeds which are edible and can be ground to yield a flour for bread making, as practiced by Bedouin tribes in the desert regions.
The seeds themselves consist of 17 to 19% oil of which up to 85% is unsaturated fatty acids (Schafferman et al., 1998). It has a relatively high linoleic acid content (Yaniv et al., 1999; Uruakpa et al., 2004; Oluba et al., 2008).
Recent studies at the King Saud University have demonstrated further potential possible as a general food cooking oil and ingredient for topical skin products (Nehdi et al., 2013). They provide a comprehensive investigation into the both the content of the oil and its antioxidative properties, especially as a source of tocopherol (122 mg/100g seed) with γ-tocopherol. Their methods included proton-NMR and FTIR and they compared the properties of the seed oil with the standard, sunflower oil. One interesting finding is that they conjecture that the seed oil could absorb UV-B radiation which lends it application in sunscreen oil. One entrepreneur has already requested further details on this and other seed oils for comparison.
References
Dane, F., Liu, F., Zhang, C. (2007) Phylogeography of the bitter apple, Citrullus colocynthis. Genetic Resources and Crop Evolution. 54 pp. 327-336
Nehdi, I.A., Sbihi, H., Tan, C.P., Al-Resayes, S.I. (2013) Evaluation and characterisation of Citrullus colocynthis (L.) Schrad seed oil: Comparison with Helianthus annuus (sunflower) seed oil. Food Chem., 136 pp. 348-353
Oluba, M.O., Ogunlowo, Y.R., Ojieh, G.C., Adebisi, K.E., Eidangbe, G.O., Isiosio, I.O. (2008) Physicochemical properties and fatty acid composition of citrullus lanatus (Egusi melon) seed oil. J. Biol. Sci. 8, pp. 814–817.
Schafferman, D., Behazav, A., Shabelsky, E. Yaniv, Z. (1998) Evaluation of Citrullus colocynthis a desert plant native in Israel as a potential source of edible oil. J. Arid Environments 40 pp. 431-439
Uruakpa, F.O., Aluko, R.E. (2004) Heat-induced gelation of whole egusi (Colocynthis citrullus L.) seeds. Food Chem. 87, pp. 349–354
Yaniv, Z., Shabelsky, E., Schafferman, D. (1999) Colocynth: Potential arid land oilseed from an ancient cucurbi. In: Perspectives on New Crops and New Uses,1st Edition.; Janick, J., Ed.; ASHS Press: Alexandria, VA, USA, pp. 257–261.
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