Crystalline structure in starch

Abstract

Many reviews have been published on the crystalline structure of the starch granule, addressing aspects such as birefringence, crystallinity, and structural models for A- and B-type starches. After a synthetic presentation of the general knowledge on this topic, the present review focuses on a critical description of the main techniques used to investigate the starch crystalline structure, some new data regarding crystalline lamellae, and the most recent models established for the 3D structure of crystalline domains in the granules. Structural and phase transitions occurring during hydrothermal treatments of starch are briefly presented as an introduction to a more detailed description of local order and orientation in amorphous starch materials. Recent results on the structure of amylose complexes which form by heating in the presence of guest molecules are discussed as well. Finally, results regarding the in vitro enzymatic synthesis of amylose, which selfassociates into gels or particles, and in vitro enzymatic extension of glycogen external chains are described. They are evaluated as biomimetic systems for a better understanding of the mechanisms involved in starch crystallization during biosynthesis as well as in the different processes used for starch modification.