Soy protein-gellan gum noncovalent complexes stabilized emulsion: Effect of heating and pH on emulsion stability

This paper investigated the effects of heating and pH on the stability of emulsions of non-covalent complexes of gellan gum (GG) and soy protein isolate (SPI). As a result, the GG-SPI complexes stabilized emulsion exhibited a minimum emulsion particle size (945 ± 23 nm), a maximum absolute values of zeta-potential (-32.7 ± 0.81 mV), the highest values of emulsion activity index (EAI) and stability index (ESI) (132 ± 4.7 min) when emulsion was prepared under the following conditions: oil phase ratio of 18 %, polysaccharide-protein proportion of 1:8 (w/w), homogeneous pressure at 80 MPa and homogeneous time at 4 min. GG-SPI emulsion had the best emulsification performance at pH 9.0 and 75 °C owing to the protein defolding occurred, the content of α-Helix increased, hydrophobic groups were exposed, and the number of negative groups on the surface of proteins increased under the high pH and high temperature conditions. The experimental results revealed the key role of heating and pH treatment for protein emulsion stability regulation, which will enrich the application of gellan gum in soy protein emulsions and provide an important theoretical basis for the future application of emulsion modification.