Use of Hydrocolloid Gums to Modify the Pasting, Thermal, Rheological, and Textural Properties of Sweet Potato Starch

Abstract

Effect of hydrocolloids (arabic, xanthan, cress seed, fenugreek, flaxseed, and okra gums) at 0.5 and 2.0% concentrations on sweet potato starch pasting, viscoelastic, textural, and thermal properties was studied. Rapid Visco Analyzer (RVA) measurements showed that the final viscosity was increased as a function of gum irrespective of their concentration except with cress seed gum. Dynamic rheological data revealed that the magnitude of the moduli was increased as a function of angular frequency and no crossovers were perceived among them. Consistency coefficient (k) was decreased by the addition of any gum and also with increasing concentration of gums except with xanthan gum at 25°C. Flow behavior index (n) data showed that starch gum blends possessed more pseudoplastic shear thinning behavior than those for the control at 25°C and pseudoplasticity was further increased with increasing concentration of xanthan, fenugreek, flaxseed, and okra gums. Texture analysis data displayed that after overnight storage of starch gels at room temperature, hardness was significantly increased by the addition of gums except for xanthan. Differential scanning calorimeter (DSC) profile showed that enthalpy was decreased by the inclusion of xanthan gum.