Effect of Protein on the Texture of Food Emulsions under Steady Flow

The texture of food emulsions was quantified as the structure factor using the backlight scattering technique. The change of the texture of food emulsions under steady flow was monitored in terms of the structure factor. The role of different types of protein (sodium caseinate and soy protein) on the change of texture of food emulsions under steady flow was studied. The emulsion stabilized by sodium caseinate was more stable under steady flow than the food emulsion stabilized by FP940 (partially hydrolyzed soy protein). The layering of caseinate submicelles in the film between the fat particles was suggested as a reason for the greater stability of the sodium caseinate stabilized emulsion under steady flow. The FP940 stabilized emulsion showed a sudden change of texture at a shear rate of 200 rad/s (the threshold), while the sodium caseinate stabilized emulsion was relatively stable under this shear rate. The FP940 stabilized food emulsion with a high fat concentration had a more ordered texture, represented as a greater structure factor; however, this texture degraded quickly under steady flow. Versa Whip 500 (highly hydrolyzed soy protein) was compared with FP940 (partially hydrolyzed soy protein) for their effects on the stability of food emulsions under steady flow. The stability of a food emulsion under steady flow improved as the concentration of Versa Whip 500 (highly hydrolyzed soy protein) increased from 1 to 2.5 wt % in the aqueous phase. The Versa Whip 500 stabilized emulsion had soy protein micelle layering in the film between the fat particles, which helped to stabilize the fat particles under steady flow.