Partitioning of a-lactalbumin and β-lactoglobulin from cheese whey in aqueous two-phase systems containing poly (ethylene glycol) and sodium polyacrylate

Partitioning behavior of the whey proteins alpha-lactalbumin (alpha-la) and beta-lactoglobulin (beta-1g) in aqueous two-phase systems prepared with poly ethylene glycol (PEG) and sodium polyacrilate (NaPA) was investigated as a function of pH and polymer concentrations. It was observed that alpha-la concentrated in the PEG phase while beta-lg concentrated in the NaPA phase. Response surface methodology was applied to optimize protein partitioning and to achieve the best conditions for their fractionation. Thermodynamic analysis based on isothermal titration microcalorimetry indicated that the partitioning of alpha-la was accompanied by endotherrnic heat and was entropically driven, while beta-lg partitioning was accompanied by exothermic heat and was enthalpically driven at low polymer concentrations and entropically driven at high polymer concentrations. Purification and yield parameters were determined using fresh whey and the results allowed for conclusion of the great applicability of this new system for alpha-la and beta-lg fractionation. 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.