Insight into succinylated modified soy protein isolate-sodium alginate emulsion gels: Structural properties, interactions and quercetin release behavior

In this study, the emulsion gel system was constructed by succinylated SPI (SSPI) emulsion together with sodium alginate (Alg). The aim was to evaluate the influence of succinylation and Alg concentration (0 %, 1 %, 1.5 %, 2 %, 2.5 %, w/v) on the emulsion gel structure and formation mechanism, the encapsulation efficiency, release behavior, and digestion properties of quercetin. The succinylation modification and the increase in Alg concentration improved the textural properties of the emulsion gels and SSPI-2 % showed the optimum water-holding capacity (91.37 %). Fourier transform infrared spectroscopy, intermolecular forces, and X-ray diffraction indicated the formation of the gel network dominated by electrostatic interactions and hydrogen bond stabilization, with a decrease in the crystal size and disruption of the molecular rigidity structure. Low-field nuclear magnetic resonance, rheology, and microstructures showed the improvement of the moisture distribution of the gels and the formation of denser and more homogeneous. The quercetin delivery properties of SSPI emulsion gels were enhanced compared to SPI emulsion gels. The encapsulation rate of quercetin was further enhanced with increasing Alg concentration, and the optimum was reached at SSPI-2 % (96.40 %). The Ritger-Peppas model describes quercetin from SPI and SSPI gels regulated by different release kinetics in gastrointestinal fluids with a favorable sustained release effect. In addition, SSPI-2 % exhibited the highest quercetin bioaccessibility (74.54 %) and chemical stability (66.81 %). This research provides novel perspectives to explore the development of innovative emulsion gels and transport systems for bioactive.