Optimization of Subcritical Fluid Extraction of Oil from Tree Peony(Paeonia suffruticosa Andr.) Seeds

An orthogonal array design was employed to optimize the subcritical fluid extraction of seed oil from tree peony(Paeonia suffruticosa Andr.). The fatty acid composition and physicochemical properties of the seed oil were analyzed. The results showed that the optimum extraction conditions were determined to be extraction at 50 ℃ and 0.5 MPa performed three times for 30 min each,resulting in an oil yield of 24.16%. Twelve fatty acids were identified in the extracted seed oil and the major fatty acids were linolenic acid(45.412 2%),linoleic acid(38.119 9%),palmitic acid(11.124 6%) and stearic acid(3.648 9%). The physicochemical indexes were as follows: relative density 0.901 3,index of refraction 1.474 2,acid value 3.25 mg/g,iodine value 175 g/100 g,saponification value 176 mg/g,and peroxide value 1.48 meq/kg.