title: Size separations of starch of different botanical origin studied by asymmetrical-flow field-flow fractionation and multiangle light scattering.
abstract: Asymmetrical-flow field-flow fractionation combined with multiangle light scattering and refractive index detection has been revealed to be a powerful tool for starch characterization. It is based on size separation according to the hydrodynamic diameter of the starch components. Starch from a wide range of different botanical sources were studied, including normal starch and high-amylose and high-amylopectin starch. The starch was dissolved by heat treatment at elevated pressure in a laboratory autoclave. This gave clear solutions with no granular residues. Amylose retrogradation was prevented by using freshly dissolved samples. Programmed cross flow starting at 1.0 mL min(-1) and decreasing exponentially with a half-life of 4 min was utilised. The starches showed two size populations representing mainly amylose and mainly amylopectin with an overlapping region where amylose and amylopectin were possibly co-eluted. Most of the first population had molar masses below 10(6) g mol(-1), and most of the second size population had molar masses above 10(7) g mol(-1). Large differences were found in the relative amounts of the two populations, the molar mass, and hydrodynamic diameters, depending on the plant source and its varieties.
authors.affiliation: Technical Analytical Chemistry, Department of Chemistry, Center for Chemistry and Chemical Engineering, Faculty of Engineering LTH, Lund University, P.O. Box 124, 221 00, Lund, Sweden. karl-gustav.wahlund@analykem.lu.se
authors.forename: Karl-Gustav
authors.initials: KG
authors.lastname: Wahlund
authors.forename: Mats
authors.initials: M
authors.lastname: Leeman
authors.forename: Stalin
authors.initials: S
authors.lastname: Santacruz
mesh_terms: D031521:Fractionation, Field Flow / Q000379:methods*; D008027:Light; D008970:Molecular Weight; D010316:Particle Size; D010944:Plants / Q000737:chemistry*; D012542:Scattering, Radiation; D013213:Starch / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D013213:Starch