Molar Masses and Sizes of Starches by High-Performance Size-Exclusion Chromatography with On-Line Multi-Angle Laser Light Scattering Detection

Abstract

Starch was characterized for analysis by high-performance size-exclusion chromatography (HPSEC) with detection by multiple-angle laser light-scattering and refractive index. Corn starches (amylopectin-to-amylose ratios of 1:0, 3:1, 1:1, and 3:7), presolubilized potato starch, and potato starch granules were analyzed. For corn starches, analysis by HPSEC revealed that weight average molar mass (Mw) and z-average root mean square radius of gyration (Rgz) decreased with increasing percentage of amylose. For potato starches, granules had a much higher Mw and Rgz than presolubilized starch. All chromatograms were polymodal in nature with at least two high Mw amylopectin components. Except for high amylose corn starch, Rgz values from this study were comparable with results from an earlier HPSEC/viscometry study. The Rgz values from microscopic studies were lower than from chromatographic studies. Keywords: starch; molar mass; size; HPSEC; light scattering