Dairy Foods: Chemistry, Processing, and Analysis Poster Presentations

Milk protein concentrate (MPC) is one of the major ingredients in foods due to its nutritional and functional properties including solubility, water binding, foaming, and emulsification. The foaming ability of milk proteins could potentially allow them to replace egg white protein; however, there is a lack of research on foaming properties of MPC. The goal of this study was to investigate the effects of salts on foaming properties of MPC. Calcium chloride, sodium citrate, and sodium chloride were mixed with MPC solutions and pH was adjusted such that the final solutions contained 5% w/w protein, 0–20 mM CaCl2 and 0–40 mM citrate, or 0–100 mM NaCl at pH 7.0. Foam was generated by whipping MPC solutions in a KitchenAid mixer. Foaming properties were determined by measuring overrun and drainage 1⁄2 life. Physical properties of pre-foam solutions, including solubility, turbidity, and particle size were measured. Interfacial shear rheology was determined using a controlledstrain and rate rheometer with a bicone geometry. Addition of 20 mM CaCl2 caused a reduction in overrun (P < 0.05) but no significant effect on foam stability. Either with or without of CaCl2, increasing citrate concentration significantly increased overrun (P < 0.05) and drainage 1⁄2 life of MPC foam. However, samples having higher citrate concentration (40 mM) only showed improvement in overrun but a decrease in drainage 1⁄2 life. Sodium chloride significantly improved overrun (P < 0.05) but had no effect on drainage 1⁄2 life. Enhanced overrun corresponded to a reduction in particle size and turbidity and an increase in solubility of pre-foam solutions. Interestingly, interfacial rheology revealed that pre-foam solutions with CaCl2 exhibited higher interfacial viscosity and interfacial elastic modulus, while the presence of citrate reduced interfacial viscosity and interfacial elastic modulus. These results indicated that appropriate concentrations and combination of salts are needed to optimize foaming properties of MPC.