Recovery of lactose and proteins from cheese whey with poly(ethylene)glycol/sulfate aqueous two-phase systems

Cheese whey is an environmental problem as an effluent, but also a source of valuable raw materials, namely proteins and lactose. In this work, Aqueous Two-Phase Systems (ATPS) were studied for the recovery of lactose, BSA, β-lactoglobulin and α-lactalbumin, key components of cheese whey. ATPS formed by PEG (molecular weights: 200–8000 g.mol−1) with sodium or ammonium sulfate were investigated. Partitioning of the selected solutes was experimentally addressed in different ATPS and pH values. Partition behavior showed that ATPS formed by PEG1500/ammonium sulfate is able to separate lactose from proteins, while PEG300/sodium sulfate ATPS may be used for protein fractionation. These separation strategies were then tested with simulated and real cheese whey. Under optimized conditions, PEG 1500/ammonium sulfate ATPS allows efficient recovery of > 95% proteins (precipitate) and 80% of lactose (bottom phase), as confirmed for both simulated and real cheese whey. The results found indicate that the proposed polymer/salt ATPS can be used to design scalable and cost-effective separation strategies to apply in cheese whey and other related wastes.