Dialdehyde Starch-Lysine Conjugates: Chemical, Structural and Functional Properties

We produced a novel starch derivative in two steps: periodate oxidation to obtain dialdehyde starch (DAS) and conjugation of DAS with lysine in a Maillard-type reaction. Compared to the native tapioca starch, DAS has significantly lower intrinsic viscosity, molecular weight, relative crystallinity, smoothness of granule surface, and swelling power, but higher solubility and light transmittance. When produced using increasing periodate concentrations from 0.05 to 3.0 N, DAS had higher carbonyl contents and swelling powers but lower recovery efficiency, intrinsic viscosity, relative crystallinity, and solubility. When produced from DAS with higher carbonyl contents, the DAS-lysine conjugates had higher degree of lysine conjugation and swelling power but lower intrinsic viscosity, relative crystallinity, granule integrity and paste transparency. This approach of conjugation can be used in slow-release applications, where different amino acids, peptides, or even proteins can be conjugated with DAS, and then cleaved and released in the stomach or other acidic media.