Synergistic effect of seed roasting and green extraction on oxidative stability in black cumin oil

Cold-pressed black cumin oil (BCO) is prone to oxidative deterioration due to its high polyunsaturated fatty acid (PUFA) content and is known for elevated acid and peroxide values. Prior studies show seed roasting reduces acid values and increases oxidative induction time (OIT), yet the PUFA-rich BCO remains oxidation-susceptible. This study demonstrated that green extraction using unroasted seed press cake enriched carotenoids (+33%) and chlorophyll (+58%) in the oil, indicating transfer of lipophilic press-cake constituents. It also enhanced antioxidant capacity, and lowered primary oxidation products (peroxides -58%, conjugated dienes -10%) in BCO, though acid values rose likely due to enzymatic activity. Furthermore, seed roasting lowered acid values by 82% and boosted thymoquinone content, while combining roasting with green extraction significantly increased OIT compared to unoptimized roasted BCO. These novel findings highlight the synergistic potential of seed roasting in combination with green extraction to valorize press cake while addressing BCO stability challenges.