Enhancing vitamin D3 bioaccessibility: Unveiling hydrophobic interactions in soybean protein isolate and vitamin D3 binding via an infant in vitro digestion model

In the domain of infant nutrition, optimizing the absorption of crucial nutrients such as vitamin D 3 (VD 3 ) is paramount. This study harnessed dynamic-high-pressure microfluidization (DHPM) on soybean protein isolate (SPI) to engineer SPI-VD 3 nanoparticles for fortifying yogurt. Characterized by notable binding affinity ( K a  = 0.166 × 10 5  L·mol −1 ) at 80 MPa and significant surface hydrophobicity ( H 0  = 3494), these nanoparticles demonstrated promising attributes through molecular simulations. During simulated infant digestion, the 80 MPa DHPM-treated nanoparticles showcased an impressive 74.4% VD 3 bioaccessibility, delineating the pivotal roles of hydrophobicity, bioaccessibility, and micellization dynamics. Noteworthy was their traversal through the gastrointestinal tract, illuminating bile salts' crucial function in facilitating VD 3 re-encapsulation, thereby mitigating crystallization and augmenting absorption. Moreover, DHPM treatment imparted enhancements in nanoparticle integrity and hydrophobic properties, consequently amplifying VD 3 bioavailability. This investigation underscores the potential of SPI-VD 3 nanoparticles in bolstering VD 3 absorption, thereby furnishing invaluable insights for tailored infant nutrition formulations.