title: Fine structures and physicochemical properties of starches from chalky and translucent rice kernels.
abstract: This work compared the molecular structures and physicochemical properties of starches obtained from chalky and translucent kernels of six rice cultivars. Starch samples were prepared according to a modified alkali steeping method. Crystallinity, pasting characteristics, and thermal properties were studied by X-ray diffraction, rapid viscosity analysis, and differential scanning calorimetry, respectively. Starch molecular size fractions (amylopectin, amylose, and intermediate material) were estimated by high-performance size exclusion chromatography, and the chain length profiles of isoamylase-debranched amylopectin were evaluated by high-performance anion-exchange chromatography with pulsed amperometric detection. Starches from chalky kernels contained less amylose (more amylopectin) and more short branch-chain amylopectin (less long branch-chain amylopectin) compared with the translucent kernel starches. Differences in starch structural features significantly correlated with observed variation in grain translucency, starch X-ray diffraction patterns, thermal properties, and pasting characteristics. Starch synthesis in chalky kernels may slightly favor glucan chain branching over chain elongation.
authors.affiliation: Department of Food Science, University of Arkansas, Fayetteville, AR 72704, USA.
authors.forename: James
authors.initials: J
authors.lastname: Patindol
authors.forename: Ya-Jane
authors.initials: YJ
authors.lastname: Wang
mesh_terms: D000687:Amylopectin / Q000032:analysis; D000688:Amylose / Q000032:analysis; D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002851:Chromatography, High Pressure Liquid; D015394:Molecular Structure; D012275:Oryza / Q000737:chemistry* / Q000235:genetics; D013213:Starch / Q000032:analysis* / Q000737:chemistry; D014783:Viscosity; D014961:X-Ray Diffraction
chemical_list: D013213:Starch; D000688:Amylose; D000687:Amylopectin