Preparation, Structural Characterization, and in Vitro Digestibility of Selenoprotein Microcapsules

This study aimed to improve the bioavailability of plant-derived selenoprotein and extend its application for the development of Se-enriched food. Microencapsulated selenoprotein was prepared by piercing-solidifying method with sodium alginate as wall material and CaCl₂ aqueous solution as curing solution, respectively. The technology process was further optimized by response surface methodology using the embedding rate of selenoprotein as response value. The micro morphology, molecular structure, thermal stability, and in vitro digestibility of products was characterized by scanning electron microscope (SEM), Fourier transform infrared spectrum (FTIR), thermogravimetric analysis (TGA), and simulating digestion experiments, respectively. The results showed that the optimal conditions were sodium alginate concentration 1.6% (w/v), CaCl₂ concentration 2% (w/v), and embedding operation temperature 49℃. The selenoprotein embedding rate could reach 87.4%. The related characterization further confirmed that selenoprotein with average diameter of (848.1±60.2) μm was effectively and tightly wrapped, and its thermal stability was also improved. The in vitro digestion trial indicated that the release rate of the selenoprotein in the gastric juice system was only 8.9%, while the cumulative release rate in the intestinal system after 13 hours was 88.2% because microcapsules could effectively protect selenoproteins and improve its stability and slow release capacity. Related research of this work may provide a new route for the high-value utilization of selenoprotein and the development of Se-enriched food.