Yield Stresses in Cooked Wheat Starch Dispersions

Wheat starch dispersions of 8–15% concentrations were cooked in the temperature range 60°–75°C for periods up to 75 min. Viscosities of the cooked dispersions were determined in a rotational viscometer at 60°C and 23°C. No yield points were observed in the viscosity behavior at 60°C. At 23°C, viscosity measurements showed yield points in the range 200–3.000 dynes/cm 2 dependent on cook time, cook temperature, concentration and cooling history. Plots of log viscosity versus log shear stress were useful in establishing the existence of yield points where the usual plots of shear rate versus shear stress were ambiguous.