Aqueous two-phase extraction for recovery of proteins from cheese whey

Aqueous two-phase extraction (ATPE), employing polymer-polymer type and polymer-salt type systems, has been used for the recovery of proteins (devoid of fat) from cheese whey. The application of ATPE resulted in differential partitioning of fat and proteins, that is, selective partitioning of the proteins to the top (polymer rich) phase while the fat to the bottom (salt rich) phase. This differential partitioning of proteins and fat has been explained based on force balance analysis. Such a partitioning behaviour is observed only in the polymer-salt type phase system and not in polymer-polymer type phase system. Effect of process parameters such as phase composition (tie line length, TLL), pH, protein concentration and phase volume ratio were studied. PEG 6000/potassium phosphate system of 23.9% w/w TLL gave the best partitioning results with highest recovery of proteins. Higher phase volume ratios during extraction have improved the recovery of proteins in extracting phase.