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Research article2010Peer reviewed

The fine structure of cassava starch amylopectin Part 1: Organization of clusters

Laohaphatanaleart, K; Piyachomkwan, K; Sriroth, K; Bertoft, Eric

Abstract

The enzyme alpha-amylase from Bacillus subtilis was applied to partly hydrolyze purified cassava amylopectin into groups of clusters, which were called domains. The domains were further size-fractionated by methanol precipitation and then subjected to a second stage of alpha-amylolysis until the rate of hydrolysis was slow in order to release the single clusters. All domain and cluster fractions were hydrolyzed with beta-amylase into beta-limit dextrins. The size distribution and chain composition of the beta-limit dextrins were analyzed by gel-permeation chromatography and high-performance anion-exchange chromatography with pulsed amperometric detection, respectively. The sizes of the clusters in the form of beta-limit dextrins were uniform with an average degree of polymerization of 67-78. The distribution profiles of B-chains were similar in all cluster fractions, which suggested that the internal structure of the cassava amylopectin clusters was homogenous. Long B-chains were involved in the interconnection of clusters in the domain fractions. These were cleaved and a new group of chains of intermediate length was produced by the alpha-amylase together with short chains. In the isolated clusters, however, some chains corresponding to long B-chains still remained, which is not predicted by the traditional cluster model of the amylopectin structure. Instead, the alternative two-directional backbone model could explain the mode of interconnection between the clusters. (C) 2010 Elsevier B.V. All rights reserved.

Keywords

Amylopectin structure; Cluster structure; Cluster interconnection

Published in

International Journal of Biological Macromolecules
2010, Volume: 47, number: 3, pages: 317-324 Publisher: ELSEVIER SCIENCE BV

    UKÄ Subject classification

    Food Science

    Publication identifier

    DOI: https://doi.org/10.1016/j.ijbiomac.2010.01.004

    Permanent link to this page (URI)

    https://res.slu.se/id/publ/47864