Effects of Different Extraction Methods on the Quality and Antioxidant Activity of Safflower Seed Oil

In this study, the ultrasonic-assisted and oscillation-assisted solvent extraction methodologies were employed to extract safflower seed oil using unshelled and shelled safflower seeds harvested from Xinjiang as raw materials. The effects of different extraction methods on the physicochemical indices and volatile components of safflower seed oil were further investigated to clarify the differences in the quality of oils extracted from unshelled and shelled safflower seeds. Results showed that the physicochemical indices of safflower seed oil extracted by different methods, including relative density, refractive index, saponification value, acid value, iodine value, peroxide value and so on, were in complance with the national standard of safflower seed oil (GB/T 22465-2008). The fatty acids of different oil samples were mainly linoleic acid (57.53%~67.95%), oleic acid (6.46%~8.12%), palmitic acid (1.87%~2.12%) and stearic acid (1.26%~1.77%). The fatty acid compositions of safflower seed oils extracted by these two different methods did not show any significant differences. The contents of trans-(2-octenal), n-hexanol and n-amyl alcohol in safflower oil obtained by the ultrasonic-assisted method were 2.74%, 14.96% and 1.93%, while those obtained by the oscillation-assisted method were 2.14%, 12.49% and 1.88%. In addition, the OSI values of safflower seed oils extracted by the ultrasonic-assisted method and the oscillation-assisted method were 6.89 h and 5.57 h, respectively. More importantly, the oils extracted from the unshelled safflower seeds exhibited significantly higher antioxidant activities (i.e. scavenging degrees of DPPH and ABTS⁺ free radicals) than those extracted from shelled safflower seeds. The results will provide a theoretical basis for the preparation and refining technology of safflower seed oil.