Volatile compounds fingerprints of black cumin (Nigella sativa L.) seed oil extracted by supercritical carbon dioxide

Black cumin (Nigella sativa L.) seed oil consists of many volatile components dissolved in the fixed-oil, mainly triglyceride. It is used as food flavoring and natural preservative. The total oil content was reported in range of 39.5-41.8 %wt., while the essential content was found in range of 0.4-2.5%wt. In this work, the seed oil samples were obtained from supercritical CO₂ (SCCO₂) extraction under various pressures (20.0-30.0 MPa) and temperatures (40-60 °C). The volatile compounds fingerprints of SCCO₂ extracted oils were analyzed by the headspace-gas chromatography (SH-GC) without using any organic solvent. The comparison of volatile compounds fingerprints obtained from SCCO₂ and n-hexane extracts and direct analysis of milled seed by SH-GC was also investigated. It was found that the extraction temperature influenced the volatile compound fingerprints, especially at the extraction pressure of 30.0 MPa. The increasing temperature reduced the amount of the mid-boiling point compounds. The SCCO₂ extracts had nearly similar volatile compounds fingerprints of milled black cumin seed without detected residue solvent.