Comparative Evaluation of SFE and Solvent Extraction Methods on the Yield and Composition of Black Seeds (Nigella Sativa)

Supercritical Fluid Extraction (SFE) conditions (temperature, pressure, and volume of CO2) were optimized to obtain high quality black seed oil rich in antioxidants. The highest extraction yield (31.7%) was obtained under the SFE condition (50°C, 400 bar, and 100 mL), whereas SFE condition (50°C, 100 bar, 200 mL) gave a low yield (0.84%) as lipids were not extracted. HPLC characterization of compounds in the SFE extracts indicates the presence of a large number of compounds in high concentrations in the extract with a low yield. The yield and composition of SFE extracts were compared with the extracts obtained by the soxhlet extraction method and the SFE extract with low yield was found to be superior. Selected SFE extracts were also subjected to GSH recovery tests, and maximum recovery (84.6%) was obtained for the extract with low yield confirming the presence of antioxidant compounds.