Thermal Properties and Dynamic Rheological Characterization of Starch Gels.

Yam (. sp.) is an edible starchy tuber with potential for being a commercial source of starch for industrial purposes, but yam starch is underutilized. The dynamic oscillatory and thermal properties of yam starches from sixteen varieties each of , , and one variety of from Nigeria were studied to determine their potential for industrial utilization. The storage modulus, loss modulus, damping factor and complex viscosity as a function of frequency (ω) of the gels, as well as the onset temperature (), peak gelatinization temperature (), end of gelatinization (), and gelatinization enthalpy of the starches were determined by standard procedures. Results showed that all the starches showed a typical elastic behavior with the magnitude of G' greater than G″ while tan δ < 1 in all varieties. Thus, the starch gels were more elastic than viscous. All the starch gels exhibited shear thinning characteristics and showed frequency (ω) independence characteristics of weak gels. varieties had the lowest ∆, while varieties had the highest. The diversity of the visco-elastic and thermal properties of the yam starch gels from different varieties and species can be an advantage in their utilization in both food and non-food industries.