RHEOLOGICAL METHOD FOR KINETICS OF DRAINAGE AND DISPROPORTIONATION OFSOY PROTEINS FOAMS

The effect of soy protein (SP) concentration and denaturation on foami ng properties was investigated. To measure drainage and disproportiona tion rates, a special method was based on measurements of time depende ncy of foam viscosity. Foam expansion reached a maximum at 3% protein concentration for denatured and 5% for native SP. Rates of drainage an d disproportionation were greatly decreased by increasing protein conc entration due to increased liquid viscosity (drainage) and to lowering of surface tension (disproportionation). Denaturation of SP increased foam expansion and decreased rate of drainage over the concentration range but lowered rate of disproportionation at > 4% protein.