Interaction of milk fat globule membrane protein with liposome and its influence on the physicochemical properties, structure, and lipid digestion of infant formula emulsions: Toward mimicking the human milk fat globule.

Differences in the interfacial composition and structure of fat globules between infant formula (IF) and human milk (HM) limit lipid digestion. To address this issue, this study incorporated milk fat globule membrane protein (MFGMP) into liposomes (Lip) to form MFGMP-Lip complexes for stabilizing model infant formula emulsions (MIFEs). The interaction between MFGMP and Lip was characterized, and its influence on the stability, interfacial properties, and in vitro lipid digestion of MIFEs was investigated. The MFGMP-Lip interaction was spontaneous and exothermic, driven by hydrogen bonds, van der Waals forces, and hydrophobic interactions. Lip promoted the exposure of hydrophobic groups in MFGMP. The complex at a 1:1 MFGMP-to-lipid mass ratio showed the lowest surface tension (8.26 mN/m) and the highest emulsifying capacity, which resulted in the emulsion (MIFE3) with the smallest particle size (427.57 nm) and highest physical stability. Microstructural and interfacial chemical composition analysis confirmed the co-localization of MFGMP, phospholipids, and cholesterol on the lipid droplet surfaces in MIFEs, exhibiting HM fat globule-like interfacial characteristics. This improvement led to higher lipid digestibility in MIFEs during in vitro digestion. The lipolysis degree of MIFE3 (83.97%) and MIFE4 (82.51%) was similar to that of HM (83.64%) and significantly higher than that of commercial IF (77.51%). Modulating lipid droplet interfacial properties based on MFGMP-Lip complexes could be an effective strategy to improve the lipid digestion of infant foods.