Fabricating hydrophilic particles with oleic acid and bovine serum albumin to improve the dispersibility and bioaccessibility of fucoxanthin in water

Biomacromolecules and dietary lipids are known to efficiently improve the hydrophilicity and intestinal absorption, respectively, of carotenoids . In this work, to simultaneously promote the dispersibility and bioaccessibility of fucoxanthin (FUCO) in a hydrophilic environment, a water-soluble delivery carrier was constructed using oleic acid (OA) and bovine serum albumin (BSA), based on the method of pH-switchable molecular self-assembly. The hydrophilic OA–BSA particles were prepared under the optimized conditions (pH shifting from 11.0 to 7.0, BSA 2.0 mg/mL, and OA/BSA molar ratios 13:1 to 30:1), with the particle sizes ranging from 120.0 nm to 160.0 nm and the Zeta-potential ranging from −35.0 mV to −45.0 mV. The fabricated OA–BSA particles were subsequently employed to entrap FUCO in water. When the FUCO/BSA molar ratio was 10:1, the transparent aqueous dispersions of the FUCO–OA–BSA complexes, with particle sizes <200.0 nm and Zeta-potentials over −30.0 mV, were obtained and a FUCO embedding rate of more than 96% was achieved. Furthermore, Fourier transform infrared spectroscopy and scanning electron microscopy results confirmed that the FUCO was completely encapsulated within the OA–BSA particles and that spherical particles with smooth surfaces were formed. In addition, in vitro simulated gastro-intestinal digestion revealed that the bioaccessibility of the FUCO reached more than 60% after its encapsulation within the OA–BSA particles. The in vivo test further confirmed that the OA–BSA particles could increase serum and hepatic responsive levels of FUCO by 6.66 and 4.39 times, respectively. These findings suggest that fatty acid-protein particles may be suitable for the hydrophilic delivery carriers of hydrophobic nutrients.