Effect of Annealing on the Physicochemical Properties and Structure of Yam Flours

The yam flours were prepared by annealing treatment to study the effects of moisture content and treatment time on the solubility and swelling force,viscosity properties,thermodynamic properties,crystal and structural properties of yam flours. After the annealing treatment,the solubility and swelling force of yam flours decreased significantly(P<0.05),the solubility decreased from 6% to 2.2%,and the swelling force decreased from 3.93 g/g to 2.47 g/g. After annealing treatment,the peak viscosity,trough viscosity,breakdown,final viscosity and setback of yam flours all dramatically decreased(P<0.05). DSC results showed that the gelatinization temperature increased after annealing,and the enthalpy had no significant change(P>0.05). The XRD results showed that the crystalline form of yam flours was changed from C type to C+V type after annealing,and its structure became more stable than that of the native yam flours. Fourier transform infrared spectroscopy declared that the position of the absorption peak did not change after annealing,while the degree of structural order increased. Annealing treatment improved the structural stability of yam flours and improved its physicochemical properties.