title: Chemical structures in pyrodextrin determined by nuclear magnetic resonance spectroscopy.
abstract: Glycosidic linkages in a pyrodextrin were identified by NMR spectroscopy for the first time. Pyrodextrin was prepared by slurrying waxy maize starch at pH 3, filtering and drying at 40°C to 10-15% moisture content, then heating at 170°C for 4h. (1)H and (13)C NMR resonances of the pyrodextrin were assigned with the assistance of 2D techniques including COSY, TOCSY, HSQC, and HMBC, all measured on a 500MHz instrument. During dextrinization, native waxy maize starch was hydrolyzed and extensively branched with new glycosidic linkages. The resulting pyrodextrin became 100% soluble in water and produced lower viscosity solutions at 30% solids. There were only 1.2% reducing ends (α-form) detected in the pyrodextrin, but 1,6-anhydro-β-d-glucopyranosyl units accounted for 5.2% of repeating units and they were thought to be at the potential reducing end. New glycosyl linkages including α-1,6, β-1,6, α-1,2, and β-1,2 were identified. The total non-α-1,4 linkages in the pyrodextrin were about 17.8% compared to 5.8% in a maltodextrin prepared by α-amylase digestion. Transglycosidation and depolymerization occurred during dextrinization, and the resulting pyrodextrin was highly branched.
authors.affiliation: Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506, USA; School of Public Health, Soochow University, Suzhou, Jiangsu, 215123, China. Electronic address: baiyanjie@suda.edu.cn.
authors.forename: Yanjie
authors.initials: Y
authors.lastname: Bai
authors.affiliation: Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506, USA. Electronic address: ycshi@ksu.edu.
authors.forename: Yong-Cheng
authors.initials: YC
authors.lastname: Shi
mesh_terms: D066241:Carbon-13 Magnetic Resonance Spectroscopy; D003912:Dextrins / Q000737:chemistry*; D006027:Glycosides / Q000737:chemistry; D015394:Molecular Structure; D066244:Proton Magnetic Resonance Spectroscopy; D012995:Solubility; D013213:Starch / Q000737:chemistry; D014783:Viscosity; D000516:alpha-Amylases / Q000737:chemistry
chemical_list: D003912:Dextrins; D006027:Glycosides; D013213:Starch; D000516:alpha-Amylases
keywords: Dextrin; Dextrinization; NMR; Pyrodextrin; Starch; Thermal decomposition