2. Metabolic Engineering, Dexa Laboratories of Biomolecular Sciences (DLBS), Industri Selatan V, Block PP no. 7, Jababeka Industrial Estate II, Cikarang, West Java 17550, Indonesia.
Optimum condition for Nigella sativa seeds oil and its bioactive compound, thymoquinone (TQ) using supercritical fluid carbon dioxide extraction (SCFE-CO2), were investigated. The optimization process was performed with Taguchi method and full factorial design (FFD) under the following condition: pressure (150, 200 and 250 bar), temperatures (40, 50 and 60°C) and carbon dioxide (CO2) flowrate (10, 15 and 20 g/min), in which solvent to feed (SF) ratio was set constant at 24. The highest yield of Nigella sativa seeds oil from SCFE-CO2 process with FFD method was 12% at 250 bar, 60°C and 20 g/min. Whereas Taguchi method was performed at 250 bar, 50°C, 10 g/min with oil yield 11.9%. The highest thymoquinone content in Nigella sativa seeds oil from both experimental design was achieved through SCFE-CO2 extraction condition at 150 bar, 60°C and 20 g/min with thymoquinone content 20.8 mg/ml. In addition, conventional methods such as high pressure soxhlet with liquid CO2, n-hexane soxhlet and percolation with ethanol were performed with oil yield 5.8%, 19.1% and 12.4%; and thymoquinone content 8.8 mg/g oil, 6.3 mg/g oil and 5.0 mg/g oil, respectively. The analysis of variance (ANOVA) with 95% confidence interval, indicates effect of pressure on Nigella sativa seeds oil yield and thymoquinone content from SCFE-CO2 process. The oil was then evaluated for its activity. The antibacterial activity of the oil from Taguchi Method, shows that all samples were unable to inhibit Escherichia coli O157 and Salmonella typhimurium. For other pathogenic bacterias, all samples show similar inhibition at concentration 10% oil for MRSA, 3% oil for Stapylococcus aureus and 3% oil for Bacillus subtilis.
Keywords: SCFE-CO2, Nigella sativa, taguchi method, full factorial design, thymoquinone, antibacterial activity