Purification and concentration of cheese whey proteins through aqueous two phase extraction

Whey is a by-product of cheese manufacture and contains proteins that can be recovered, but lactose presence limits its use. Proteins can be separated with aqueous two-phase extraction (ATPE), thus the objective was to evaluate this strategy to recuperate proteins from whey attending lactose elimination. An ATPE system with (NH4)2SO4 and polyethylene glycol 4000 (PEG4000) was studied at 25°C. As PEG4000 diminished the volume ratio between phases diminished and a biphasic system was maintained in absence of the polymer. Minimum protein recovering and lactose elimination were 54.5% and 62.1% with mixtures having 25% PEG4000 and 12.1% (NH4)2SO4, but values were 93.0% and 72.3%, respectively, with 0.1% PEG4000 and 34.7% (NH4)2SO4. Therefore, whey incorporated with (NH4)2SO4 in concentration higher than 34% and without polyethylene glycol can be used in ATPE systems to maximize lactose elimination and protein recovering and to concentrate proteins up to 2.45 times through a non-energy strategy.