Capillary rheometry of soy isolate dough

Viscosity of 30 and 48% soy isolate (Promine-D) dough is determined using an Instron capillary rheometer at 298K, 333K and 363K. Thermal transitions of 10 to 100% soy isolate dough are measured using a Perkin-Elmer Differential Scanning Calorimeter (DSC-2) over 310 to 350K. The observed behavior of the soy isolate doughs is explained in terms of a network based on temporary crosslinks, possibly hydrogen bonds. Additionally, factors which complicate viscosity measurement of these doughs are discussed including yield stresses, melt fracture and sample reservoir pressure losses.