Synthesis and application of epoxy starch derivatives

Epoxy starch derivatives were synthesized by epoxidation of allylated starch. The reaction was performed with low substituted 1-allyloxy-2-hydroxypropyl-waxy maize starch (AHP-WMS: degree of substitution (DS) of 0.23) using hydrogen peroxide and acetonitrile Via a two step spectrophotometric assay, it was determined that epoxy-WMS contained 0.13 +/- 0.03 mmol epoxy groups per gram dry allylated starch which corresponds to DS value of 0.025. Enzymatic digestibility, swelling capacity and solubility were significantly reduced after epoxidation. The detailed chemical structure of epoxy-WMS was characterized by enzymatic hydrolysis followed by chromatographic and mass spectrometric techniques. Only a small amount of epoxidized oligomers was found in the enzymatic digested products of epoxy-WMS. Apparently, the epoxidation reaction is highly efficient but subsequent reactions of epoxy groups lead to a considerable amount of cross-links and diol groups. Additionally, epoxy starch derivatives were successfully applied as carrier matrix for immobilization of an enzyme. (C) 2009 Elsevier Ltd. All rights reserved.