Nigella sativa L.: Chemical composition and physicochemical characteristics of lipid fraction

Physicochemical properties of two Nigella seed varieties, having a Tunisian and Iranian origin, were determined. Physical and chemical analyses of crude oils extracted from the seeds by a cold solvent method were also performed. The following results (on a dry-weight basis) were obtained for Tunisian and Iranian varieties, respectively: protein 26.7% and 22.6%, oil 28.48% and 40.35%, ash 4.86% and 4.41%, and total carbohydrate 40.0% and 32.7%. The major unsaturated fatty acids were linoleic acid (50.3–49.2%), followed by oleic acid (25.0–23.7%), while the main saturated fatty acid was palmitic acid (17.2–18.4%). Myristic, myristoleic, palmitoleic, margaric, margaroleic, stearic, linolenic, arachidic, eicosenoic, behenic and lignoceric acids were also detected. Thermal profiles of both Nigella seed varieties, determined by their DSC melting curves, revealed different thermograms. Sensorial profiles of Tunisian and Iranian seed oils were defined through the CieLab (L∗, a∗, b∗) colour, oxidative stability by Rancimat test and viscosity. Physicochemical properties of the oils for Tunisian and Iranian varieties, respectively, include: saponification number 211 and 217, peroxide value 5.65 and 4.35, iodine index 120 and 101, and an acidity of 22.7% and 18.6%. Results suggested that Nigella seed oil could deserve further consideration and investigation as a potential new multi-purpose product for industrial, cosmetic and pharmaceutical uses.