Effects of polysaccharide type on the structure, interface behavior, and foam properties of soybean protein isolate hydrolysate-polysaccharide Maillard conjugates

This study investigated the structure, interface behavior, rheological properties, and foaming properties of soybean protein isolate hydrolysate (SPIH) after covalent binding via the Maillard reaction with gum Arabic (GA), sodium alginate (SA), xanthan gum (XG), or soybean polysaccharides (SPSS). Covalent binding with polysaccharide increased the content of random coils and decreased that of α-helices, suggesting the unfolding of SPIH. The unfolding and disordered protein structure led to enhanced foaming properties of SPIH-polysaccharides compared to those of SPIH alone. In particular, SPIH-SPSS displayed the highest foaming capacity (203.83 ± 3.40 %), which is due to its highest solubility (95.12 ± 0.15 %) and surface hydrophobicity (4470.47 ± 64.29), as well as the lowest zeta potential and surface tension. Meanwhile, SPIH-XG displayed the highest foaming stability (83.84 ± 2.80 %) due to its highest adsorbed protein content (24.77 ± 0.26 %) and viscoelasticity. These results indicate that the foaming properties of SPIH are effectively improved by Maillard reaction with a suitable polysaccharide. The hydrolysate-polysaccharide covalent complex may have expanded applications as an effective foaming agent in foods and beverages.