Physiochemical properties of Saudi <i>Nigella sativa</i> L. (‘Black cumin’) seed oil
Nesrain Farhan, Nadia Salih, Jumat Salimon
Abstract
The seeds of Nigella sativa L. (Ranunculaceae), commonly known as black cumin seeds and Habat Al-barkah in Saudi Arabia, are used extensively for flavouring and medicinal purposes. This work reported the study of physiochemical properties of Saudi black cumin seed oil (BCSO). The results of hexane extraction showed that black cumin seeds are rich in oil (43.7%). All the oil samples show high saponification values and low unsaponification values. High iodine values (122.7 mg/100 g) showed high degree of unsaturation (86%) for Saudi BCSO with about 60% of dominant linoleic acid (C 18:2 ). The volatile compounds presence in Saudi BCSO were extracted using steam distillation method and analyzed using gas chromatography mass spectrometer (GC/MS). The results showed that the volatile compounds such as p -cymene (31.50 ± 0.51%) and thymoquinone (25.35 ± 0.37%) were dominantly high in Saudi BCSO. Other compounds such as 3,5-dimethyl cyclohexanol, α-thujene, carvacrol, paeonol and longifolene were also present. Vitamin E was analyzed using High performance liquid chromatography (HPLC)-fluorescence method. The total concentrations of vitamin E were 451 ppm. The Saudi BCSO showed high content of linoleic acid (59.8%). The HPLC results showed that major triacylglycerols (TAGs) of Saudi BCSO were 1-oleoyl-2,3-dilinoleoylglycerol (OLL; 37.7 ± 0.4%) and 1,2,3-trilinoleylglycerol (LLL; 35.9 ± 0.3%). On the other hand, minor TAGs present were 1-palmitoyl-2,3-dilinoleylglycerol (PLL; 6.7 ± 0.9%), 1,2,3-trioleylglycerol (OOO; 6.4 ± 0.5%) and 1,2-dioleyl-3-linoleylglycerol (OOL; 5.7 ± 1.1%). The Saudi BCSO exhibited specific physicochemical properties and might be used for medicinal applications.