Multilayer assembled MFGM mimetics improve digestive fate of human milk structural lipids

Current infant formulas lack the native multilayer structure of breast milk fat globule membrane (MFGM), impacting lipid digestion. In this study, the inner layer material and concentration of the biomimetic fat globule membrane were optimized by comparing particle size, Zeta-potential and interface protein load. It was found that compared with sodium caseinate (CN) and whey protein (WP), when the lactoferrin (LF) concentration was 2 %, the particle size was lower (277.85 ± 6.15 nm) and Zeta-potential value was higher (19.67 ± 1.27 mv). Using milk phospholipid (MPL) as the outer layer material, when the MPL concentration was 2 %, the emulsion had a smaller particle size (291.33 ± 1.15 nm) and a better stability (10.22 ± 0.62 %). Therefore, the biomimetic multilayer membrane was constructed by electrostatic layer-by-layer deposition of 2 % LF and 2 % MPL. Combining Fluorescence and Fourier transform infrared spectroscopy (FTIR), the interaction between LF and MPL molecules in the LF-MPL multilayer structure is primarily a spontaneous, endothermic process driven by hydrophobic forces, exhibited superior stability (except thermal stability) than LF monolayer membrane. The results of in vitro digestion showed that compared with LF, WP and WP-MPL emulsions, LF-MPL emulsions had the highest free fatty acid (FFA) release rate of 69.97 %. LF-MPL enhanced gastric stability and promoted intestinal lipolysis and improved the degree of lipid digestion. In addition, LF-MPL promoted the absorption and utilization of triglyceride (TAG) in cells and animals, and secretion and upregulated lipid absorption genes (FATP4, DGAT1, APOB, APOA4, MTTP). These findings demonstrate that biomimetic LF-MPL multilayers improve lipid digestion, absorption, and bioavailability, providing a theoretical basis for designing more breast milk-like infant formulas.