2.2. Transferring of Monascus pigments by Winsor I microemulsion
extraction
Transferring of Monascus pigments from nonionic surfactant
aqueous solution to ionic liquid (IL) was conducted by ionic liquid
based Winsor I microemulsion extraction [17]. The clear supernatant
fermentation broth (20 ml) was mixed with 5 g (4 ml) IL
(ionic liquid, [Bmim]PF6) in 50 ml tube, which was subjected to
Winsor I microemulsion extraction by setting up at a room temperature
for phase separation for at least 1 h. The mixture was separated
into two phases, where the lower one was excess IL phase
and the upper one was Wm (oil-in-water microemulsion) phase
(Winsor I microemulsion). The Wm phase was transferred into
another tube. The excess IL phase was further washed with water
for 3 times to remove the contaminated nonionic surfactant in the
excess IL phase. Based on the volume and the corresponding
pigments absorbance at 410 nm, the fraction of Monascus pigments
in the excess IL phase or Wm phase was determined.