Rheological Characteristics of Halberd Wheat Starch

Abstract

AbstractThe non‐Newtonian behavior and dynamic viscoelasticity of Halberd wheat starch (23.0% amylose content) pastes were determined with a rheogoniometer. The flow curves, at 25°C, of Halberd starch pastes showed plastic behavior at concentrations of more than 4.0%. The shear viscosity of the starch pastes decreased gradually with an increase in temperature at concentrations less than 4.0%, but remained constant at a concentration of 5.0%. The storage modulus of the starch pastes increased with increasing concentration and remained high during increase in temperature up to 80°C. Almost the same storage modulus was observed upon addition of urea (4.0 M) to the paste at low temperature (0°C), and the modulus stayed at a large value with increase in temperature up to 60°C, which was estimated to be a transition temperature; then it decreased rapidly with further temperature increase. A transition temperature of 60°C was also observed in the dynamic viscosity. A very large storage modulus and dynamic viscosity were observed in alkaline solution (0.05 M NaOH) at low temperature (0°C), both quantities decreased slightly with increase in temperature up to 25°C, which was estimated to be a transition temperature, then decreased rapidly with further increase in temperature. A possible intermolecular hydrogen bonding between amylose and amylopectin molecules is proposed.