Enhancing fucoxanthin bioavailability: Octyl-modified maltodextrin micelles and ultrasound-assisted encapsulation

Micelles are nanostructures capable of encapsulating hydrophobic substances within their hydrophobic cores, enabling their dispersion in aqueous media. This enhances the solubility, stability, and bioavailability of encapsulated bioactive compounds and allows for their controlled release. In this study, maltodextrin chains were chemically modified by adding hydrophobic octyl groups onto their backbone through an esterification reaction. As the degree of substitution increased, both the particle size of the micellar-like aggregates and the critical aggregation concentration (CAC) gradually decreased. The encapsulation efficiency and loading capacity exhibited a positive correlation with the degree of substitution. Furthermore, ultrasonic treatment, by inducing a cavitation effect, was found to enhance hydrophobic interactions within the micelles and significantly improve the encapsulation capacity and compensate for the lower degree of substitution. It also improved composite properties and imparted environmental stability to the micelle-like aggregates. In vitro modeling of the digestive process demonstrated that fucoxanthin-loaded micelle-like aggregates can effectively avoid gastric release while showing significantly enhanced intestinal release. As expected, the octyl-modified maltodextrin (MD-C8) markedly improved the bioaccessibility of fucoxanthin (49.57%) and increased the micellization rate (90.96%) during simulated gastrointestinal digestion. These findings indicate that MD-C8 is an effective delivery carrier for functional biomolecules. Combined with the approach of ultrasound-assisted techniques, it shows great potential for the applications in the encapsulation of hydrophobic compounds.