Effect of phospholipid matrix on emulsion stability, microstructure, proteolysis, and in vitro digestibility in model infant formula emulsion.

The effects of adding different phospholipid (PL) matrices [milk sphingomyelin (SM) vs soy phosphatidylcholine (PC)] on emulsion stability, microstructure, and in vitro simulated lipid digestion were examined using a Model Infant Formula Emulsion (MIFE). The emulsion stability of MIFE increased significantly with PL addition (0.1 and 0.2 %). Compared to sole MIFE or MIFE + PC, the incorporation of SM resulted in increased emulsion stability (p < 0.05) and a greater amount of free fatty acid release (p < 0.05) during in vitro simulated digestion. This was mainly due to the reduction of intensive droplet aggregation, thus providing a large surface area and improved digestibility. This is further experimentally supported by the evolution of particle size distribution, zeta-potential, and microstructure analysis using confocal laser scanning microscopy. The incorporation of SM in the emulsion formation significantly delayed digestion of β-lactoglobulin during in vitro digestion. Lipid digestibility in MIFE was altered depending on the type of PL matrix, and SM displayed a superior effect to PC. Thus, the creation of a novel emulsion interface by the appropriate selection of emulsifiers can be used to improve lipid digestion in infants and obtain desirable nutritional consequences.