Evaluation of phytochemical profile and oxidative stability of mechanically pressed seed oils from five aromatic plants

The aim of the study was to determine the recoverability, composition, and stability of oils pressed from spice seeds as novel sources of bioactive ingredients. Oils were pressed (solvent-free extraction) from five spice seeds: caraway (Carum carvi), cumin (Cuminum cyminum), lovage (Levisticum officinale), ajwain (Trachyspermum ammi) from the Apiaceae family and nigella (Nigella sativa) from the Ranunculaceae family. Liquid, gas, and supercritical fluid chromatography were used to determine triacylglycerols, fatty acids, tocopherols, tocotrienols, sterols, squalene, and carotenoids, and oxidative stability was observed during storage at 21 and 60 °C. Nigella and ajwain had the highest crude oil content and recovery by mechanical pressing. The fatty acid profiles of the Apiaceae species were dominated by petroselinic acid, the highest proportion being in ajwain (64.66%), while nigella predominantly contained linoleic acid (58.08%). Triacylglycerols were primarily made up of petroselinic acid in Apiaceae species, and of linoleic and oleic acid in nigella. Apiaceae species’ oils contained squalene in variable amounts. The sterol content ranged 247.83 (nigella) – 1056 mg 100 g− 1 (lovage). The main carotenoid in all oils was lutein, followed by zeaxanthin, nigella seed oil was lowest in carotenoids. All oils’ tocochromanol profiles were dominated by tocotrienols (T3), especially γ-T3 in caraway and ajwain, α-T3 in cumin, and almost exclusively β-T3 in nigella (131.17, 68.42, 91.14 and 24.52 mg 100 g− 1, respectively). While sterol and carotenoid contents were similar to conventional oils, the pressed spice seed oils were rich in less common tocotrienols.