The Variation of Relative and Reduced Viscosity with Concentration in Wheat and Barley Aqueous Extracts

Viscosity of grain aqueous extract is a function both of the concentration of NSP and of its degree of polymerization. The objectives of this study were to quantify the relative and reduced viscosities of wheat and barley aqueous extracts at various concentrations and to determine the effect of centrifugation rotational speed on the viscosity of these solutions. Both relative and reduced viscosity increased as the cereal concentration in water increased from 0.05 to 0.50 g/mL. The viscosities of wheat and barley extracts isolated by centrifugation at 10,000 rpm, due to an increased rate of sedimentation, were lower than the viscosities of extracts separated by centrifugation at 5,000 rpm. The relative viscosity of water extracts correlated very well with the wheat (r = 0.9678) and barley (r = 0.9690) concentration We have observed, both in wheat and barley, a higher correlation between reduced viscosity and concentration than between relative viscosity and concentration.