Stability and in vitro digestion behavior of astaxanthin-loaded Pickering emulsions stabilized by OSA-modified starch: Influence of oil phase content.

Astaxanthin, a lipid-soluble carotenoid, is widely recognized for its health-promoting properties. However, its use in functional foods is limited due to its low water solubility, chemical instability, and poor bioavailability. This study evaluated the potential of esterified starch-stabilized emulsions as astaxanthin carriers. The effects of the oil phase content on the emulsion properties, stability, and in vitro digestion behavior of the emulsions were investigated. All emulsions exhibited adequate encapsulation efficiency (>80 %) for astaxanthin. Moreover, the particle size and viscosity of the emulsions increased with an increasing oil phase content. The emulsion with a 10 % oil phase content (E-10 %) showed high retention of astaxanthin (>40 %) under the temperature, pH, and ionic strength conditions tested and long-term stability (42 days). On the other hand, the release of free fatty acids and bioaccessibility of astaxanthin were negatively correlated with the oil phase content. And the bioaccessibility of astaxanthin was increased to 11.66 % (for E-10 %). Under a constant emulsifier concentration, E-10 % and E-20 % exhibited a thicker interfacial layer at the oil/water interface. Based on this, a smaller particle size may favor oil droplet dispersion and inhibit droplet floatation and aggregation, improving emulsion stability. Therefore, this study provides useful information on the effect of the oil phase content in esterified starch-stabilized Pickering emulsion delivery systems.