High Amylose Corn Starch Gels—Investigation of the Supermolecular Structure

Abstract

Aqueous gels based on two high amylose corn starch (HACS) genotypes with different amylose (AM) contents (HYLON V [HACS-50] and HYLON VII [HACS-70]) are prepared by gradation of the polymer concentration (6 and 9% w/w) and storage duration (1 and 14 days). The supermolecular structure of the wet gels is investigated by means of confocal laser scanning microscopy (CLSM), and the dried starch gel material examines crystallographically using X-ray diffraction (XRD) and morphologically using scanning electron microscopy (SEM). In particular CLSM reveals that the gel structure shows changes with the storage time. XRD experiments reveal the existence of the B-type crystalline structure as well as a remarkable portion of the V-type, and higher crystallinity (Xc) is found after long-term storage. Observation of the dried gel material's surface facilitates the assumption of a fractal-based arrangement (structure of retrograded starch) within the starch gel network. The results are discussed closely with obtained data related to the molecular level of the gel matrix involved starch polymers, which are reported in previous publications.