Effect of Preparation Concentration on the Physicochemical Properties of Retrograded Starch from Lotus Seed

The effect of preparation concentration on the physicochemical properties of retrograded starch(RS)from lotus seed was investigated. The thermal stability,swelling power and solubility,viscosity,rheological properties of samples were determined,respectively. Thermogravimetric analysis(TGA)showed that RS5% and RS40% of contained more volatile substances,while RS20% contained more relatively stable heat-stable components among samples. As the starch concentration increases,the swelling powers of all samples reduced,and the solubility increased,as well as the viscosity decreased. Moreover,the swelling power and solubility increased with the increasing temperature. It could be seen from the static rheological results that all samples exhibited shear thinning characteristics,and the viscosities of RS5%,RS10%,and RS20% were higher than those of RS30%,RS40%,and RS50%. Furthermore,from the results of dynamic rheology,when the angular frequency was less than 10 rad·s^-1,the storage modulus of all samples was not affected by the angular frequency. when the angular frequency was greater than 10 rad·s^-1,the storage modulus of RS5%,RS10%,and RS20% decreased with the increasing angular frequency,whereas the storage modulus of RS30%,RS40%,and RS50% increased with the increasing angular frequency. The loss modulus of all samples increased with the increasing angular frequency. All in all,the preparation concentration of starch displayed a significant effect on the physicochemical properties of retrograded starch from lotus seed. The physicochemical properties of retrograded starch with low concentrations of starch(5%,10%,20%)had a significantly different compared to retrograded starch with high concentrations(30%,40%,50%).