Soybean Protein Dispersions at Acid pH. Thermal and Rheological Properties

The influence of pH, protein concentration, and ionic strength, on rheological properties of thermally treated acidic soy protein dispersions, was studied. Structural changes due to pH effect and thermal treatment were analized. DSC‐thermograms at pH 3.5 showed a shoulder at 74.11±0.16°C that could be attributed to both β‐conglycinin and the hexameric form of glycinin; and a peak at 81.88±0.29°C corresponding to 11S dodecameric form. At pH 2.75 one endotherm corresponded to denaturation of β‐conglycinin. The acidic dispersions presented pseudoplastic behavior with app values higher than those at pH 8.0. At pH 3.50 the ± app was higher than at pH 2.75.The maximum viscoelasticiy was obtained with addition of 0.1 and 0.25M NaCl in the dispersions of pH 3.50 and 2.75, respectively. The increase in viscoelasticity was enhanced by the formation of 11S native fraction dimers.