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Starch-lipid complexes were prepared from high amylose starch (HAS) with stearic acid (SA) or potassium stearate (PS) at different molar concentrations. The complexes (HAS-PS) formed between HAS and PS showed polyelectrolyte characteristics with ζ-potential ranging from −22.2 to −32.8 mV, and the electrostatic repulsion between anionic charges restricted the starch chain reassociation and facilitated the formation of V-type crystalline structures upon cooling. The hydrophobic effects enabled recrystallization of the SA, and the HAS-SA complexes exhibited weaker V-type crystalline structures than the HAS-PS complexes; both HAS-SA/PS complexes were of a similar "mass fractal" type, with a dimension varied from 2.15 to 2.96. The HAS-SA complexes had a considerable content of resistant starch (RS, 16.1~29.2%), whereas negligible RS was found in the HAS-PS complexes. The findings from the present study imply that the molecular order of starch chains and the macro-structures of starch particles are more important to regulate the digestibility of starch-lipid complexes than the crystalline structures. [ABSTRACT FROM AUTHOR]

As biodegradable and eco-friendly bio-resources, polysaccharides from a wide range of sources show steadily increasing interest. The increasing fossil-based production of materials are heavily associated with environmental and climate concerns, these biopolymers are addressing such concerns in important areas such as food and biomedical applications. Among polysaccharides, high amylose starch (HAS) has made major progress to marketable products due to its unique properties and enhanced nutritional values in food applications. While high amylose-maize, wheat, barley and potato are commercially available, HAS variants of other crops have been developed recently and is expected to be commercially available in the near future. This review edifies various forms and processing techniques used to produce HAS-based polymers and composites addressing their favorable properties as compared to normal starch. Low toxic and high compatibility natural plasticizers are of great concern in the processing of HAS. Further emphasis, is also given to some essential film properties such as mechanical and barrier properties for HAS-based materials. The functionality of HAS-based functionality can be improved by using different fillers as well as by modulating the inherent structures of HAS. We also identify specific opportunities for HAS-based food and biomedical fabrications aiming to produce cheaper, better, and more eco-friendly materials. We acknowledge that a multidisciplinary approach is required to achieve further improvement of HAS-based products providing entirely new types of sustainable materials. [ABSTRACT FROM AUTHOR]

Alkali treatment is used for melt extrusion film formation with corn starch, but optimal conditions for this procedure are still unknown. In this study, the changes in properties and structure of high amylose corn starch (70%) films with different concentrations of sodium hydroxide (NaOH), prepared by melting extrusion, were investigated. With increasing sodium hydroxide concentrations, the tensile strength of the high-amylose starch film decreased gradually, while the elongation at break increased. The tensile strength of the high amylose starch (HAS) film with 2% NaOH-treatment was 10.03 MPa and its elongation at break was 40%. A 2% NaOH-treatment promoted the orderly rearrangement of starch molecules and formed an Eh-type crystal structure, which enlarged the spacing of the single helix structure, increased the molecular mobility of the starch, and slowed down the process of recrystallization; a 10% NaOH-treatment oxidized the hydroxyl groups of the high amylose corn starch during extrusion, formed a poly-carbonyl structure, and initiated the degradation and cross-linking of starch molecule chains. [ABSTRACT FROM AUTHOR]