Separation of α‐Lactalbumin and β‐Lactoglobulin by a Convenient Liquid‐Solid Extraction System: Application to Milk Whey

A liquid‐solid extraction system based on Tween 80/phosphate was developed. Under the optimized conditions (9 wt % Tween 80, 1.6 : 1 (molar ratio) K₂HPO₄ : NaH₂PO₄, 1.25 mol/L total phosphate, pH = 7.4), α‐Lactalbumin (α‐La) and β‐Lactoglobulin (β‐Lg) were separated with recovery rates of 87.6 % (in the solid polymeric phase) and 98.2 % (in the salt aqueous phase), respectively. Under the effects of water and salt, the solid phase had the ability to form a new liquid‐solid extraction system, and 85.1 % of α‐La could be reversely extracted into the new salt aqueous phase. Following dialysis against water, proteins obtained through extraction and reverse extraction, were analyzed by polyacrylamide gel electrophoresis (PAGE) and thin‐layer scanning. The method was applied successfully to separate α‐La and β‐Lg from milk whey.