Glycated Trichosanthes kirilowii protein isolate stabilizes W/O/W emulsions for co-encapsulation of vitamin C and β-carotene: Characterization, stability, and in vitro digestion

TPI–glucose conjugates showed improved oil–water interfacial activity. • TPI–glucose conjugates effectively stabilized W/O/W emulsions. • Optimized emulsions encapsulated 89.40% vitamin C and 68.27% β-carotene. • Bioaccessibility was 3.13 and 4.52 times that of free vitamin C and β-carotene. • Prepared W/O/W emulsions had good physical, environmental, and storage stability. This work elucidated the stabilization mechanism of water-in-oil-in-water (W/O/W) emulsions co-encapsulating vitamin C and β-carotene using Trichosanthes kirilowii seed protein isolate (TPI)-glucose conjugates (G1, G2, and G3). Compared with native TPI, the glycated TPI exhibited enhanced interfacial activity, characterized by reduced interfacial tension and elevated rates of diffusion, penetration, and reorganization. The glycated TPI-stabilized W/O/W emulsions demonstrated smaller droplet sizes, higher absolute zeta potential values, and improved emulsifying and rheological properties. Notably, the conjugate-stabilized W/O/W emulsions achieved efficient co-encapsulation of vitamin C and β-carotene. Particularly, the double emulsion stabilized by G2 yielded encapsulation efficiencies of 89.40% and 68.27% for the two bioactive compounds, respectively, and their bioaccessibility was remarkably enhanced to 3.13 and 4.52 times that of their unencapsulated counterparts. Furthermore, the double emulsions stabilized by the conjugates exhibited a lower Turbiscan stability index, higher resistance to elevated temperatures, extreme pH values, and high NaCl concentrations, as well as favorable storage stability. This study demonstrates the potential of TPI-glucose conjugates as promising interfacial stabilizers for W/O/W emulsions and provides important theoretical support for elucidating the regulatory mechanism of plant proteins in interface-dominated food systems. Download: Download high-res image (372KB) Download: Download full-size image