Effects of Different Extraction Methods on the Quality of Eucommia ulmoides Seed Oil

The aim of this study was to evaluate the effects of soxhlet extraction method(SE),subcritical extraction method(SBE)and supercritical CO₂(SC-CO₂)extraction method on the yield,main physical and chemical properties,as well as fatty acid composition of Eucommia ulmoides seed oil. The results showed that Eucommia ulmoides seed oil yield achieved by SE,SBE and SC-CO₂ were 34.47%,28.42% and 18.68%,respectively. SE showed the highest peroxide value((0.087±0.002) g/100 g)and acid value((1.64±0.02) mg/g),but the lowest relative density(0.87±0.01)and iodine value((190.4±0.8) g/100 g),which demonstrated that the quality was the worst. Compared with SE,the Eucommia ulmoides seed oil extracted by the SBE and SC-CO₂ showed better product characteristics. Significant difference(P<0.05)in color analysis was observed among three kinds of methods.Eucommia ulmoides seed oil extracted by SC-CO₂displayed the highest brightness and color. Moreover,these oil samples had nearly identical fatty acid composition which was measured by gas chromatography,and the main fatty acid were oleic acid,linoleic acid and α-Linolenic acid,but the content of various fatty acids was different. In addition,the content of unsaturated fatty acids was SC-CO₂ > SE > SBE. In comprehensive consideration,SC-CO₂ could produce Eucommia ulmoides seed oil with the best quality,SBE was also a new green process for extracting Eucommia ulmoides seed oil if comprehensive consideration of cost factors and ease of industrial operation. This study laid the theoretical foundation for the development and utilization of Eucommia ulmoides seed oil.