Chitosan surface-modified bovine serum albumin-oleic acid self-assembled complexes: Improving the thermal stability, controlled release and bioaccessibility of fucoxanthin

Fucoxanthin (FUCO) is a marine xanthophyll carotenoid with widespread potential physiological functions. However, poor water solubility and chemical instability limit FUCO's processing adaptability and bioavailability. In this study, chitosan surface-modified bovine serum albumin (BSA)-oleic acid (OA) self-assembled complexes were fabricated to improve the thermal stability as well as the controlled release and bioaccessibility of FUCO during gastrointestinal digestion. The results showed that glucose-grafted chitosan (GGC) could surface modify BSA-OA complexes by non-covalent affinity adhesion, resulting in a stable hydrophilic dispersion system with a polydispersity index <0.25 and a Zeta potential > -20 mV. Fourier transform infrared spectroscopy and transmission electron microscope observations revealed that GGC covered the surface of BSA-OA particles through hydrogen bonding, hydrophobic and electrostatic interactions. The GGC-BSA-OA delivery system captured FUCO with >88.00% encapsulation efficiency. Additionally, embedding FUCO in the GGC-modified BSA-OA complex improved its thermal stability. In vitro, gastrointestinal digestion simulations showed that the GGC-modified protein shell had a controlled-release effect on FUCO, which prevented acidic pH from destroying FUCO due to premature release during gastric digestion and released it during intestinal digestion. As expected, GGC-BSA-OA, an encapsulated carrier, dramatically improved the FUCO's digestive stability (retention rate >74.00%), bioaccessibility (>54.42%), and micellization rate (>70.00%) in simulated gastrointestinal digestion. These findings suggested that GGC-BSA-OA as a delivery vehicle could effectively improve FUCO's thermal processing stability and absorbability.