Direct Analysis of Chains on Outer Layer of Amylopectin through Partial Hydrolysis of Normal Starch by Isoamylase.

Short-amylose chains released from normal corn starch with isoamylase were studied to establish an analytical method for getting directly structural information of amylopectin. The partial hydrolysates obtained without separation of amylose and amylopectin were fractionated into three fractions (fr.1, fr. 2 and fr. 3) by gel chromatography of Toyopearl HW-50S. The chain-length distribution of the fr. 3 containing shortish chains was analyzed by using HPAEC-system equipped with a pulsed amperometric detector (HPAEC-PAD). Although the shortamylose chains in the fr. 3 came from not only amylopectin but also branched amylose, it was estimated that the chains relating to branched amylose were minor in the hydrolysate. The analytical method getting directly a general information of amylopectin was conducted to typical rice starches produced in Japan as an applied experiment.