Whey protein partitioning in aqueous two-phase systems

Whey is a by-product of cheese manufacturing that has proteins that can be recovered, but they are very diluted and in a mixture with lactose, which limits their use. The aqueous two-phase extraction technique (ATPE) is a procedure with potential to separate proteins. The objective was to evaluate the behavior of an aqueous protein-(NH4)(2)SO4 extraction system applied for the recovery of whey proteins, considering the reduction of lactose. A binodal phase diagram was constructed using a high throughput screening technique. Ammonium sulfate was dissolved at concentrations between 22 and 40 % using whey as solvent. The volume of the top phase of the systems was less than that of the bottom one, but the increase in (NH4)(2)SO4 caused a gradual increase at the top phase. Around 80 % of whey protein concentrated at the top phase, while over 79 % of lactose was at the bottom phase. The ATPE technique has the potential to separate proteins from whey and the best alternative is based on systems with 34 % (NH4)(2)SO4.