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Abstract: The objective of this study was to determine the thermodynamic parameters (Δ tr G, Δ tr H and Δ tr S) associated with lysozyme and conalbumin partitioning in aqueous two-phases systems (ATPS). Influence of salt type and polyethylene glycol (PEG) concentrations on the partition coefficient of lysozyme and conalbumin from egg white was studied. The evaluated ATPS were composed of PEG 1500 and inorganic salts (sodium citrate and sodium sulfate) at a temperature of 25°C and pH 7.0, with PEG 1500gmol−1 concentrations of 14%, 16% and 18% (mass basis). Partitioning of lysozyme in PEG–citrate ATPS was enthalpically driven, however the PEG–sulfate ATPS was entropically driven. The tested systems can be employed for the separation of these two proteins in egg white, due to the fact that lysozyme migrates toward the polymeric phase and conalbumin to the saline phase in both ATPS. A high recovery of conalbumin in the saline phase of the PEG–sulfate ATPS was determined to be enthalpically driven. [Copyright &y& Elsevier]

Abstract: In order to develop a new strategy for β-lactoglobulin (β-lg) removal from whey protein, partitioning of α-lactalbumin (α-la), β-lg and glycomacropeptide (Gmp) was studied using aqueous two phase systems (ATPS). A system composed of 13% (w/w) polyethylene glycol (PEG, average molar mass 2000g/mol) and 13% (w/w) potassium phosphate was used at 25°C. A central composite rotatable design (CCRD) associated to the response surface methodology (RSM) was applied to investigate the effects of NaCl concentration and pH on the partition of these proteins. It was found that α-la and Gmp partitioned to the top phase rich in PEG, whereas β-lg partitioned to the bottom phase rich in salt. According to the RSM, optimal conditions for β-lg removal where found where pH was equal to 6.7 and salt concentration was 0.35mol/L. Under these conditions, the partition coefficient K α was 0.48 and K Gmp was 0.92. On the other hand, the partition coefficient K β was only 0.01. In such conditions β-lg preferentially concentrates in the bottom phase, while the top phase exclusively contains the proteins α-la and Gmp. Fractionation of the proteins from fresh whey was performed in a three stage cross-flow extraction system. The extraction yield for β-lg in the bottom phase was 97.3%, while the yields for α-la and Gmp in the top phase were 81.1% and 97.8%, respectively. [Copyright &y& Elsevier]

Abstract: This work aimed to study the partition of cheese whey proteins α-lactoalbumin and β-lactoglobulin using aqueous two-phase system by applying the cloud point extraction technique. The cloud point temperatures were determined under different concentrations of copolymer and salt. The system providing the best protein separation conditions was 20mass% of copolymer PE61 and potassium phosphate salt solution of 100mM, at pH 7. The protein α-lactoalbumin remained preferentially in the aqueous phase and the β-lactoglobulin was transferred to the copolymer phase. [Copyright &y& Elsevier]

Abstract: This study evaluates the influence of type of salt and temperature on the partition coefficient of caseinomacropetide (CMP) to determine the best conditions for the recovery of CMP in aqueous two-phase systems (ATPS) composed by poly(ethylene glycol) (PEG) 1500 and an inorganic salt (potassium phosphate, sodium citrate, lithium sulfate or sodium sulfate). In all systems, CMP presented affinity for the PEG-rich phase. The PEG1500+lithium sulfate showed the highest values of partitioning coefficient. In addition, thermodynamic parameters (ΔH°, ΔS°, ΔG°) as a function of temperature, were calculated for the system PEG1500-sodium citrate at different PEG concentrations and the results imply thermodynamic differences between partitioning of CMP in this system. [Copyright &y& Elsevier]