Sodium alginate-mediated interfacial structuring in soy protein-quercetin composite emulsions: A synergistic strategy for encapsulation and bioavailability enhancement of lipophilic bioactives.

This study explored the mechanisms by which sodium alginate (SA) improved the stability and release efficiency of lutein (Lut) encapsulated in binary complexes of soybean protein isolate (SPI) and quercetin (Que). The addition of SA increased the fluorescence intensity of the interfacial protein, resulting in increased β-turn (22.94 %) and random coil contents (27.32 %), thereby enhancing interfacial flexibility. Specially, 0.02 % (w/v) SA effectively reduced the emulsion particle size, increased the absolute value of ζ-potential, and improved overall emulsion stability. Moreover, low concentrations of SA enhanced the antioxidant capacity of the emulsions and promoted the bioaccessibility of lutein (48.12 ± 1.77 %) and quercetin (53.85 ± 0.68 %). These results demonstrated that moderate SA addition can effectively enhance the stability and bioaccessibility of the SPI emulsion system. This work provided theoretical guidance for designing protein emulsion-based carrier systems for co-embedding and delivery of functional factors with varying solubility properties in future.