Steady and Dynamic Shear Rheological Properties of Buckwheat Starch-galactomannan Mixtures

Abstract

This study investigated the effects of galacomannans (guar gum, tara gum, and locust bean gum) on the rheological properties of buckwheat starch pastes under steady and dynamic shear conditions. The power law and Casson models were applied to describe the flow behavior of the buckwheat starch and galactomannan mixtures. The values of the apparent viscosity (ηa,100), consistency index (K), and yield stress (σoc) for buckwheat starch-galactomannan mixtures were significantly greater than those for the control, indicating that there was a high synergism of the starch with galactomannans. The magnitudes of storage modulus (G′) and loss modulus (G″) for the starch-galactomannan mixtures increased with increasing frequency (ω). The dynamic moduli (G′, G″), and complex viscosity (η*) for the buckwheat starch-galactomannan mixtures were significantly higher than those for the control.