Physicochemical and biochemical characterizations of some Tunisian seed oils

Four Tunisian vegetable oils extracted from seeds ( Nigella sativa , Opuntia ficus indica , Pistacia lentiscus and Hibiscus sabdariffa ) have been characterized in this study. The following parameters were determined: acidity, peroxide value, saponification value, specific extinction coefficients K232, K270, chlorophylls and carotenoids content. The triglyceride and tocopherol compositions of the oils were determined using reversed phase high performance liquid chromatography with diode array detection (HPLC-DAD) and the fatty acids (FA) and phytosterol compositions were determined using a gas chromatography (GC) with a flame ionization detector (FID). Polyunsaturated fatty acids were predominant in all tested samples except in Pistacia lentiscus oil where monounsaturated fatty acids were predominant. Major FA were linoleic and oleic acids. β-sitosterol was the most abundant phytosterol. All samples had high content of TAGs with an equivalent carbon number of 44, 46 and 48. Nigella sativa oil had the highest content of tocopherols.