SURFACE-PROPERTIES AND EMULSIFICATION BEHAVIOR OF DENATURED SOY PROTEINS

Soy protein isolate was physically (heat pretreatment) and chemically (urea, guanidine.HCl, and cleavage of SS bonds) modified in order to d issociate subunits, unfold the protein and improve surface properties: hydrophobicity, emulsification capability, and stability. Heat pretre atment as well as chemical treatment with urea or guanidine.HCl or red uction of disulphide bonds, will improve emulsification performance in comparison to native soy protein isolate. Significant differences in reduction of surface tension of water in the presence of native and mo dified proteins were observed (45 and 35 dynes/cm respectively). Measu rements of fluorescence indicated that the relative hydrophobicity of the soy protein was also improved (from 600 to 1360) after heat pretre atment or contacting the soy protein with 8M urea solution.