To analyse the oil content in the emulsion and aqueous phase
from combined extraction, 20 ml of petroleum ether 40/60 was
added to freeze dried samples and mixed by vortex for 30 s. The
samples were incubated overnight, followed by centrifugation
at 3000 × g (4
◦
C, 20 min). Two phases, petroleum ether contain-ing extracted oil at the top and remaining solid at the bottom,
were formed and separated. Petroleum ether was removed from
the collected oil using rotary evaporator. Oil content was deter-mined by weighing. Oil content of the residue was calculated by
difference