Mechanism of fat globule size and surface composition regulating in vitro dynamic digestion, absorption and transport of structured emulsions

The digestive behavior of fat globules is influenced by the structural differences in lipid between breast milk (BM) and infant formula (IF), however, it is still unclear how the size and surface structure of fat globules regulate the lipid adsorption and transport. Four emulsions stabilized by caseinate (CA) or milk fat globule membrane (MFGM) with large (3–5 μm, L) and small (0.3–0.5 μm, S) droplets size, named CA-L, CA-S, MFGM-L and MFGM-S, were fabricated to simulate the fat globules in BM and IF. Compared to CA-stabilized emulsions, MFGM-stabilized emulsions showed quicker fat digestion and faster absorption in vitro and in vivo. Moreover, MFGM-L displayed lower digestibility and higher absorptivity than those of MFGM-S. Cell transport study further confirmed MFGM-L could promote more chylomicrons secretion and better up-regulate gene expression associated with fat absorption and transport to enhance the cellular uptake of lipids. The digestion behavior and absorption of fat globules could be altered by their interfacial composition and particle size, and MFGM-L, which possessed a similar structure of fat globules in BM, was able to promote cellular uptake of lipid digesta.