pH-modulated pea protein-β-glucan and carboxymethyl chitosan double-layer complex coacervate microcapsules: Efficient vitamin D3 encapsulation and functional fortification of surimi

Vitamin D 3 (VD 3 ) is a fat-soluble vitamin essential for regulating calcium and phosphorus metabolism. However, VD 3 is unstable when exposed to high temperatures, light, and other environmental factors, necessitating effective encapsulation methods for supplementation. This study aimed to develop a microencapsulation system for VD 3 using complex coacervates formed from pea isolate protein (PPI) and β-glucan (OG), coated with carboxymethyl chitosan (CMCS) via electrostatic deposition. The results demonstrated that the optimum pH for PPI-OG and PPI-OG-CMCS complex coacervates was 4.0 and 5.0, respectively, with their formation primarily driven by ionic bonds and hydrogen bonds. Microcapsules prepared with PPI:OG:CMCS ratios from 1:1:1 to 4:1:1 all demonstrated excellent thermal stability and ultraviolet (UV) resistance. The 1:1:1 group achieved the highest vitamin D 3 encapsulation (92.52 %) and UV shielding efficiency due to its densest CMCS surface coating. Incorporating 15 % microcapsules into cod surimi improved whiteness, enhanced gel network density, increased water retention to 88.75 ± 0.35 %, and provided superior 3D printing accuracy compared to 5 %-20 % addition levels. Analysis showed hydrophobic interactions and disulfide bonds were the main driving forces. These findings suggest that PPI-OG-CMCS microcapsules are a promising approach for stabilizing VD 3 and fortifying surimi products, with potential applications in food technology and 3D printing.