Edible insect proteins - carrageenans microspheres for β-sitosterol encapsulation: Oxidative stability and in vitro...

β-sitosterol is the most abundant phytosterol, but it exhibits low stability and bioaccessibility, requiring effective delivery systems. In this study, nine β-sitosterol-loaded microspheres were produced using edible insect proteins (T. molitor, A. domesticus, L. migratoria) and κ-, ι-, or λ-carrageenan via complex coacervation and spray-drying. The resulting spherical microcapsules (<15 μm) showed strong protein-polysaccharide interactions, particularly with κ- and ι-carrageenan, which induced β-sheet-rich structures and improved stability. λ-carrageenan produced more flexible, α-helical microspheres with lower oxidative stability. Lipid peroxidation was inhibited by up to 95%, although λ-CG variants exhibited 2-3× higher oxidation. HS-SPME/GC-MS confirmed the suppression of volatile oxidation markers. β-sitosterol retention reached 66-95%, largely depending on carrageenan type. In vitro digestion showed low oral (9-15%) and moderate gastric release (28-39%), with the highest release in the intestinal phase (38-54%), resulting in overall bioaccessibility exceeding 85% for all formulations.