Supercritical CO₂ Extraction and Characteri-zation of Thymoquinone-Rich Nigella sativa L. Seed Oil: A Process Optimization Framework Using RSM

Abstract

Background: Post-pandemic interest in plant-derived bioactive compounds has renewed attention on Nigella sativa L. seeds and thymoquinone (TQ), a principal bioactive constit-uent. Efficient recovery of TQ-rich N. sativa seed oil is important for its potential applications in functional food and health-related formulations.
Method: Supercritical carbon dioxide (SC-CO₂) extraction was employed to recover N. sativa seed oil and TQ. The effects of extraction pressure, temperature, and seed particle size were investigated, while CO₂ flow rate was maintained at 0.012 kg min⁻¹. Response surface methodology (RSM) was used for process modelling and optimization. The extracted oil was characterized using GC–MS/MS, GC–FID, fatty acid profiling, FTIR, NMR, and SEM.
Result: The highest TQ concentration of 4.06% (w/w) was obtained at 15 MPa, 40 °C, and 0.87 × 10⁻³ m particle size. TQ was confirmed and quantified using GC–MS/MS and GC–FID. The optimized conditions effectively recovered TQ-rich N. sativa seed oil. Chroma-tographic, spectroscopic, and microscopic analyses further characterized the extracted oil's chemical and structural properties.
Conclusion: SC-CO₂ extraction combined with RSM provides an effective approach for optimizing TQ-rich N. sativa seed oil recovery and characterization. The integrated extraction and analytical framework offers a systematic basis for process optimization and evaluation of the chemical and structural properties of the resulting oil.