Recovery in aqueous two-phase systems of lutein produced by the green microalga Chlorella protothecoides

In this study the potential use of aqueous two-phase system (ATPS) to establish a viable process for the recovery of lutein from the green microalga Chlorella protothecoides is evaluated. The partitioning behaviour of lutein, a representative model of natural compounds of commercial interest, was investigated in a polyethylene glycol (PEG)-phosphate system. An evaluation of system parameters including PEG molecular mass, the concentrations of PEG, phosphate and product concentration was conducted, to estimate conditions under which lutein partitions preferentially to the top phase whilst cell debris partition to the opposite phase. The necessary addition of ethanol to the ATPS for the dissolution of lutein affected the phase formation and such effect was evaluated using the change in the volume ratio produced. ATPS extraction comprising Vr=1.0, PEG 8000 22.9% (w/w) and phosphate 10.3% (w/w), pH 7.0 provided the conditions for the concentration of lutein into the upper phase and the cell debris preferentially to the bottom phase. The use of ATPS resulted in a primary recovery process to obtain lutein with an overall product yield of 81.0±2.8%. The findings reported here demonstrate the potential of ATPS for the further development of a prototype process to recover lutein from C. protothecoides as a first step for the generic application of this technique.