Effects of drying methods on the emulsifying properties of micellar casein powder

Micellar casein powder (MCP), obtained by drying casein micellar solution, has gained attention as a natural functional food ingredient. This study systematically compared the effects of freeze drying (FD), spray drying (SD), and electrostatic spray drying (ESD) on the emulsifying properties of MCP. Emulsions prepared from MCP using different drying methods exhibited significant differences in particle size, zeta potential, and stability. Compared with emulsions prepared with sodium caseinate, the emulsions stabilized with both FD and ESD MCPs had higher stability but larger average particle sizes and lower absolute zeta potential values. The ESD MCP-stabilized emulsion had the highest stability, whereas the SD MCP-stabilized emulsion had the largest particle size and lowest stability. Confocal laser scanning microscopy combined with rheological analysis indicated that all MCP-stabilized emulsions formed a unique weak gel network structure. The ESD MCP-stabilized emulsion showed the highest viscosity and most densely packed protein network, which were consistent with its stability. These findings suggest that the formation of a weak gel structure and high viscosity are crucial in stabilizing MCP-stabilized emulsions. This study provides theoretical and practical insights for the development of high-performance casein-based emulsifiers.