Effect of extraction solvents on physicochemical, phytochemical, thermal, structural, and rheological properties of halim (Lepidium sativum) seed oil

Halim ( Lepidium sativum ) seed and its oil remain underutilized despite their nutritional value and health-promoting potential. The present study investigated the effect of different extraction solvents (hexane, petroleum ether, acetone, and ethanol) on the physicochemical, phytochemical, thermal, structural, rheological properties, and fatty acid profile of halim seed oil. The highest oil yields were obtained with hexane (23.94%) and petroleum ether (24.23%), followed by acetone (20.45%) and ethanol (6.20%). Acetone-extracted oil exhibited a greener hue, whereas ethanol-extracted oil showed the highest phytochemical content and oxidative stability. The total phenolic and flavonoid contents of ethanol-extracted oil were 1.76 mg GAE/g and 2.44 mg QE/g, respectively, with corresponding DPPH, ABTS, and FRAP antioxidant activities of 46.19%, 45.25%, and 100.55 mg AAE/g. Fatty acid profiling revealed a high proportion of α-linolenic acid (33.16–34.40%), indicating that halim seed oil is a valuable plant-based source of omega-3 fatty acids. FTIR analysis confirmed the presence of characteristic triglyceride functional groups, including ester carbonyl (C = O), aliphatic C–H, and ester C–O bonds, while DSC revealed distinct crystallization and melting transitions influenced by solvent type. Rheological analysis indicated Newtonian flow behaviour, with rheological data fitting the Arrhenius model, and morphological observations demonstrated oil-bearing microstructures in the flour before and after extraction. PCA and Pearson’s correlation analysis revealed significant relationships among the measured attributes, providing insights into the functional versatility of halim seed oils. Overall, halim seed oil exhibits promising nutritional and functional potential as a bioactive edible oil and a plant-derived source of omega-3 fatty acids.