Astaxanthin encapsulation in microgel-stabilized emulsions and alginate-based microparticles: analysis of in vitro digestion and bioaccessibility

Abstract

Astaxanthin (AX) is a potent natural antioxidant, but its chemical structure makes it susceptible to degradation under digestion conditions. Different delivery systems have been used to protect this bioactive compound as it passes through the gastrointestinal tract to improve its bioaccessibility. This study evaluated three systems under simulated digestive conditions: a soybean oil emulsion containing AX stabilized with whey protein aggregates (MSE), and two alginate-based emulsion microgel particles (EMP1 and EMP2) encapsulating the emulsion. All systems protected the AX emulsion in the gastric phase, with similar lipolysis levels in the intestinal phase. However, AX bioaccessibility differed by the end of the intestinal phase, being higher in the alginate-encapsulated systems. Confocal laser scanning microscopy showed faster coalescence of MSE droplets during digestion, which may limit AX bioaccessibility compared to the alginate-encapsulated systems. These findings showed that soybean oil emulsions coated with whey protein aggregates and encapsulated in alginate microparticles improved AX bioaccessibility, suggesting that they may serve as a novel functional food ingredient to effectively deliver lipophilic bioactive compounds.