Structural properties of fractionated starch polymers and their dependence on the dissolution process

A combination of sedimentation field flow fractionation (SdFFF) with multiangle laser light scattering (MALLS) was applied to the grain level destructured potato and waxy corn starch in solution. The molar mass and radius distributions were obtained simultaneously. Separation was observed for a radii range of 50-500 nm. Degradation upon heat exposure was found depending mainly on the exposure time and less on the temperature. A detailed analysis of the particle scattering factors (angular dependence of the scattered light) revealed small differences in the internal structure of potato and waxy corn starches. Both starches showed the behavior of only weakly swollen, branched clusters. Potato starch appeared to be slightly more expanded than waxy corn starch. Self-similar structures were observed with fractal dimensions of 2.4 +/- 0.1. The deviations from theoretical predictions using the mean field approximation could result from excluded volume effects and heterogeneity in branching.