Effect of Alkali Treatment on Structure and Properties of High Amylose Corn Starch Film

• Published in: Materials Vol. 12; no. 10; p. 1705
• Main Authors: Qin, Yang, Zhang, Hui, Dai, Yangyong, Hou, Hanxue, Dong, Haizhou
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 26.05.2019; MDPI
• Subjects: Aging; alkali treatment; Carbonyls; Caustic soda; Crosslinking; Crystal structure; degradable starch film; Elongation; Extrusion; Fourier transforms; Glycerol; high amylose starch; Hot pressing; Humidity; Hydroxyl groups; Lasers; Mechanical properties; melting extrusion; Molecular structure; Molecular weight; NMR; Nuclear magnetic resonance; Recrystallization; Sodium hydroxide; Spectrum analysis; Tensile strength; United States > US; China; melting extrusion; alkali treatment; degradable starch film; high amylose starch
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/MA12101705

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 E -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.