Abstract: The optimal conditions for extracting oil from Aquilaria agallocha (Lour.) Roxb.with supercritical CO₂ were studied.The contents of fatty acids in refined essential oil were determined.On the basis of single factor experimental methods,flow rate of CO₂,extraction pressure,extraction temperature,extraction time and concentration of the entrainer on the extraction ratio of raw material oil were studied by orthogonal array design.Then,the obtained essential oil was further refined by molecular separation technology.Finally,the contents of fatty acids in the essential oil were determined by gas chromatography.Experimental results showed that the order of factors affecting extraction ratio of oil from raw material was flow rate of CO₂>extraction pressure>extraction temperature>concentration of the entrainer ethanol>extraction time.The highest extraction ratio of 3.34% in raw material oil was obtained with a flow rate of CO₂ of 30 L/h,extraction temperature of 40 ℃,extraction pressure of 20 MPa,extraction time of 3 h and concentration of the entrainer of 80% ethanol.After molecular distillation treatment,the content was 0.935% for liquid essential oil under the distillation temperature of 80 ℃ and distillation pressure of 1 Pa.Gas chromatographic analysis revealed that there were thirty-six kinds of fatty acids in liquid essential oil,among which the contents of palmitic acid,oleic acid and linoleic acid ranked in the top three,and their total content accounted for 45% of the total fatty acids.The extraction method has the advantages of good selectivity,stable and reliable,which is suitable for extraction of oil from Aquilaria agallocha (Lour.) Roxb.

Key words: supercritical CO₂ extraction;extracting oil of Aquilaria agallocha (Lour.) Roxb., optimization of extraction technology, molecular separation technology, essential oil, gas chromatography, fatty acids