Petroleum ether 40/60 (10 ml)
was added carefully to the funnel to extract the free oil, but not
the oil in the emulsion. After incubation for 1 h, the three phases
were collected in separate containers. Petroleum ether from free oil
phase was removed using rotary evaporator, and oil content was
determined by weighing. Emulsion and a known amount of aque-ous phase sample were freeze-dried; all samples were stored at −18◦C until analysis