Oil extraction
Unhulled silflower seeds (700 g) were ground, and hexane (2.5 L) was
added. The mixture was heated at 55 °C in an oven for 6 h, filtered, and
the solvent was evaporated with a rotary evaporator. The defatted meal
was extracted again with hexane (2.5 L) at 55 °C for 3 h. The combined
oil was dissolved in 200 ml hexane, stored in a freezer (-20 °C)
overnight, and filtered. Solvent was removed with a rotary evaporator
and then a vacuum pump. The exactly the same conditions were used to
extract oil from unhulled sunflower seeds. The oils were stored under
argon until analyses. Oil contents are reported as the average values of
duplicate extractions.