Influence of calcium fortification on physicochemical properties of whey protein concentrate solutions enriched in α-lactalbumin

In this study, three whey protein concentrate systems enriched in α-lactalbumin, produced using membrane filtration (LAC-M), selective precipitation (LAC-P) and ion-exchange chromatography (LAC-IE), were fortified with calcium chloride (CaCl2) at 0–5 mM and changes in physicochemical properties studied. Binding of calcium (Ca2+) occurred for LAC-P in the range 0.00–2.00 mM, with an affinity constant (Kd) of 1.63 × 10−7, resulting in a proportion of total protein-bound calcium of 81.8% at 2 mM CaCl2. At 5 mM CaCl2, LAC-P had volume mean diameter (VMD) of 638 nm, while LAC-M and LAC-IE had VMD of 204 and 3.87 nm, respectively. Changes in physicochemical properties were dependent on the approach used to enrich α-lactalbumin and concentrations of other macromolecules (e.g., phospholipid). The results obtained in this study provide fundamental insights into the influence of fortification with soluble calcium salts on the physicochemical stability of next-generation whey protein ingredients enriched in α-lactalbumin