Dietary fatty acid-mediated protein encapsulation simultaneously improving the water-solubility, storage stability, and oral absorption of astaxanthin

A growing number of studies suggest that fatty acids (FAs) as ligands can improve protein's affinity to hydrophobic small molecules. Therefore, this work investigated FA-mediated protein encapsulation to simultaneously improve the water-solubility, storage stability, and oral absorption of astaxanthin (ASTA). As the main dietary FAs, lauric acid (LAA, C12:0), palmitic acid (PA, C16:0), stearic acid (SA, C18:0), oleic acid (OA, C18:1), linoleic acid (LA, C18:2), arachidonic acid (AA, C20:4), and docosahexaenoic acid (DHA, C22:6) were compared. The results showed that all the selected FAs increased the efficiency of bovine serum albumin (BSA) in encapsulating ASTA. The self-assembled particles mediated by SA exhibited smaller particle sizes, a higher Zeta potential, and better clarity in water. Contrarily, DHA led to a sharp increase in particle size and turbidity. All the fabricated FA-BSA complexes significantly (P < 0.05) improved the ASTA storage stability, while the three saturated Fas (SFAs) performed better than the unsaturated ones (SA > PA > LAA > OA > AA > LA > DHA). The simulated digestion results showed that except for DHA, the FAs with longer carbon chain lengths or unsaturated double bonds played a better role in improving ASTA's bioaccessibility. The in vivo absorption results further confirmed that the protein encapsulation mediated by C18–C20 FAs was more conducive to ASTA absorption. These findings suggest that FA-protein complexes may be suitable as the hydrophilic delivery carriers for hydrophobic nutrients. However, different FAs may play different roles in regulating nutrient stability and absorption.