Partitioning studies of α-lactalbumin in environmental friendly poly (ethylene glycol)--citrate salt aqueous two phase systems.

Aqueous two-phase systems (ATPS) formed by polymer and salt have been utilized to enrich the desired biomolecule into one of the phase with higher yield and purity. The eco-friendly, biodegradable poly ethylene glycol (PEG) and different citrate salts were chosen as ATPS phase components to investigate the partitioning behavior of α-lactalbumin (α-La). System factors and process parameters such as type and concentration of salt, molecular weight and concentration of PEG, pH, temperature and the effect of additives were studied and the results are discussed in detail. PEG 1000-tri-potassium citrate system yields high partition coefficient of 20 with a better yield of 98 % in the top phase. The addition of NaCl as an additive and acidic pH lowers the yield of α-La in the top phase. Influence of phase volume ratio (V(r)) on partitioning was studied and found that the partition coefficient remains almost constant along the tie line. High yield was achieved at a V(r) of 3.5 at the tie line length of 50.63 (%, w/w).