Cereal Chem 41:157 - 172.  |  VIEW ARTICLE

Rheology of Soy Protein Dispersions. Effect of Heat and Other Factors on Gelation.

S. J. Circle, E. W. Meyer, and R. W. Whitney. Copyright 1964 by the American Association of Cereal Chemists, Inc. 

The rheological properties of relatively concentrated aqueous dispersions of a commercial edible isolated soy proteinate preparation were studied. In the absence of heat, the viscosity rises exponentially with increased concentration. In concentrations above 7% by weight, heat causes thickening and then gelation, the temperature threshold being 65 C. Rate of gelling and gel firmness are dependent primarily on temperature, time of heating, and protein concentration. In concentrations 8-14%, gels are formed within 10 to 30 min. at 70-100 C., but are disrupted if overheated at 125 C. Above 16 to 17% the gels are firm, resilient, and self-supporting, and less susceptible to disruption by overheating. The addition of salts to 10% dispersions generally lowers the viscosity of the unheated dispersions, but raises that of the heated dispersions. The viscosities of both unheated and heated 10% dispersions are raised by added soy oil, soy lecithin, wheat starch, carboxymethylcellulose or carrageenan. The specific disulfide-reducing agents, sodium sulfite and cysteine, profoundly lower the viscosity of both unheated and heated 10% dispersions, and prevent gelation.