Impact of phase separation of soy protein isolate/sodium alginate co-blending mixtures on gelation dynamics and gels properties

The influence of sodium alginate (SA) on soy protein isolate (SPI)-based co-blending system gelling properties was studied under thermodynamic compatibility and incompatibility conditions using a direct addition (SPI/SA) or co-drying (SPI/SA-CO) process. For an SPI/SA (30:1) or SPI/SA-CO (30:1) system, the addition of too little SA did not significantly modify the SPI, and the gelation temperature (Tgel) and storage modulus (G′) were similar to an SPI solution alone. For SPI/SA (20:1) and SPI/SA-CO (10:1), the Tgel and G′ were between the values for solutions of SPI or SA alone; however, SPI/SA-CO (20:1) and SPI/SA-CO (10:1) gels could nearly double the equilibrium value of G′ (Geq′), thus improving the barrier and mechanical properties of the final formed films. The cryo-transmission electron microscope morphology of the SPI/SA-CO (20:1) and SPI/SA-CO (10:1) systems after heating was of the core-shell type in which the core comprised SPI gel.