Improvement of gelation properties of soy protein isolate emulsion induced by calcium cooperated with magnesium

The aim of this study is to investigate the cooperation effects of calcium (CaSO 4 ) and magnesium (MgCl 2 and MgSO 4 ) salts on the rheological and microstructural properties, and water holding capacity (WHC) of soy protein isolate (SPI) emulsion-based tofu gels. Small-deformation rheology indicated that the aggregation power of the three coagulants follows the order of MgCl 2 > MgSO 4 > CaSO 4 , and the coagulants containing MgSO 4 (5 and 10 mM) and MgCl 2 (5 mM) promote to produce stronger gels with greater gel firmness and rigidity. When compared with single CaSO 4 as the coagulant, a low concentration of Mg 2+ helped to form compact protein aggregates and facilitated gel homogeneity and resistance to deformation. The WHC of the gels was significantly enhanced (p < 0.05) by the action of 5 mM MgSO 4 . The relationships between aggregates induced by the coagulants and gel properties, as well as the influencing mechanism were discussed. The findings provide valuable information for understanding the coagulant-related gelation mechanism of protein and the application of SPI emulsion-based gels with improved properties in food industry.