Preparation, characterization, and encapsulation capability of the hydrogel cross-linked by esterified tapioca starch.

The modified starch-based hydrogels were prepared by crosslinking modified starch with sodium trimetaphosphate. Modified starch was obtained by esterification of tapioca starch with maleic anhydride. The degree of substitution (DS) increased significantly from 0.078 to 0.258 as the content of maleic anhydride increased from 6.67% to 33.33%. Fourier transform infrared spectroscopy demonstrated that starch was successfully esterified. In addition, the thermal properties of modified starch-based hydrogels were investigated by differential scanning calorimeter and thermogravimetry analysis, which proved that hydrogels had better thermal stability. Esterified starch-based hydrogels showed excellent pH sensitivity by measuring of swelling degree. When DS was 0.250, the adsorption capacity and encapsulation efficiency of starch-based hydrogels were 399.23 μg/g and 80%, respectively, which exhibited satisfactory embedding properties for curcumin. Therefore, esterified tapioca starch-based hydrogels could be as the encapsulating materials to protect bioactive substances, which provided a theoretical basis for their application in food field and pharmaceuticals industry.