Separation of α-Lactalbumin and β-Lactoglobulin in Whey Protein Isolate by Aqueous Two-phase System of Polymer/Phosphate

Abstract

Abstract Poly(ethylene glycol-ran-propylene glycol)monobutyl ether/phosphate aqueous two-phase system (ATPS) coupled with HPLC was developed for the separation of α -lactalbumin and β -lactoglobulin in whey protein isolate (WPI). The main parameters relevant to this method were investigated and optimized. The effects of pH value, volume ratio of the solution of polymer and KH 2 PO 4 , concentration of NaCl and WPI on the partition of α -lactalbumin and β -lactoglobulin in whey protein isolate were investigated. The results showed that an efficient separation of both proteins in whey protein isolate was achieved by an ATPS comprising of 4 mL of poly(ethylene glycol-ran-propylene glycol) monobutyl ether solution (40%, w/w ) and 4 mL of 15.5% KH 2 PO 4 solution (15.5%, w/w ). When the addition of NaCl was 0.40 g per 10 mL, the concentration of WPI was 1 mg mL −1 and pH = 4.0, α -lactalbumin was separated to the top phase while β -lactoglobulin to the bottom phase with the yield of 98.23% and 96.56%, respectively.