On the Building Block and Backbone Concepts of Amylopectin Structure

The molecular structure of the starch components has been a focus of research since it was discovered that starch is transformed into sugar by treatment with acid or barley malt extract in the beginning of the 19th century. Only in 1940 was it definitely recognized that starch contains two glucan polymers, wherein amylose was defined as the linear component and amylopectin as the branched polymer. Since then, the structure of amylopectin has been exhaustively investigated, and during the years several models have been suggested, of which the cluster model has obtained the most acceptance. During the last decade, however, experimental results have been obtained that are not entirely in favor of this model, and an alternative, two-directional backbone model was proposed. This article discusses the latter model and its impact on our understanding of the structure, properties, and synthesis of the starch granule.