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Abstract:
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.

Keywords:
Edible insect protein, Carrageenans, β-Sitosterol, Microencapsulation, Oxidative stability, Bioaccessibility

Abstract:
This study investigates the application of edible insect protein–chitosan (IP/CS) complex coacervates, derived from T. molitor, A. domesticus, and L. migratoria proteins combined with low-, medium-, or high-molecular-weight chitosans, as stabilizers in Pickering emulsions aimed at enhancing emulsion stability and improving the retention of bioactive compounds. The underlying hypothesis posits that IP/CS can function as effective stabilizing systems in Pickering emulsions, providing high overall stability, low susceptibility to destabilization, and efficient encapsulation of lipophilic bioactives. Experimental results showed that IP/CS-based Pickering emulsions achieved high β-sitosterol retention, ranging from 56 % to 91 %. Emulsion stability was primarily attributed to electrostatic interactions and hydrogen bonding within the coacervates. In addition, an effective stabilization mechanism was identified, involving the physical integration of oil droplets into the IP/CS matrix, which contributed to reduced flocculation. Fourier-transform infrared (FTIR) spectroscopy and rheological analysis confirmed the presence of hydrogen bonding and indicated a viscous character of the emulsions, while ζ-potential measurements revealed surface charge properties that further supported emulsion stabilization. These findings demonstrate the role of intermolecular interactions in maintaining the integrity of oil-in-water (O/W) Pickering emulsions stabilized by IP/CS complexes.

Keywords:
O/W Pickering emulsion,Edible insect protein,Chitosan,Complex coacervates,Stability,Retention,Phytosterols