The role of glycinin in the formation of gel-like soy protein-stabilized emulsions

The gel-like behavior of soy protein-stabilized emulsions has been not well investigated yet. Based on our previous work (Food Hydrocolloids, 2013, 30:61), this study was undertaken to unravel the role of individual soy globulins (glycinin and β-conglycinin) in the formation of the gel-like emulsions processed by microfluidization. The rheological behavior and microstructure of unheated and preheated (85 °C, 15 min) soy globulin-stabilized emulsions, formed at a total protein concentration of 6% (w/v) with various glycinin contents, were characterized. The results indicated that gel-like emulsions could be formed for the preheated soy globulins only at glycinin contents above 65%, with the gel stiffness progressively increasing with the glycinin content. The gel network formation was tightly related to strengthened inter-droplet attractive interactions (and hydrophobic interactions in particular), especially among the adsorbed glycinin at the interface. Analyses of droplet size, creaming experiments and interfacial protein concentration (Γ) suggested that the formation of these gel-like emulsions could be largely attributed to bridging flocculation of oil droplets, during which denatured glycinin adsorbed at the interface played a vital role. These results confirmed that denatured glycinin largely determines the gel-like behavior of soy protein-stabilized emulsions. The findings are of great importance for the understanding of the properties and stability of soy protein-stabilized emulsions, as well as the utilization of these gel-like emulsions in food formulations, e.g., as carriers or delivery systems for heat-labile lipid-soluble ingredients.

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