The effect of different dissolution

The effect of different dissolution procedures on molecular characteristics of waxy starches from corn and
barley were evaluated using a MALLS (batch-mode) detector, principally to understand the role played by
different solvents. Starches were dissolved in aqueous solutions of: (1) 90% DMSO, (2) 2 M KOH and (3)
90% DMSO/2 M KOH, and stored for 15 days at 22 C with shaking. Weight-average molecular weight
(Mw) and z-average radius of gyration (Rz) were determined at intervals ranging from 0 to 15 days.
Regardless of starch source and dissolution procedures, Mw and Rz of amylopectin (AP) decreased with
increasing storage time. Decrease in Mw followed the order: 90% DMSO > 2 M KOH > 90% DMSO/2 M
KOH. However, decrease in Rz followed the order: 2 MKOH > 90% DMSO/2 MKOH > 90% DMSO. The study
indicated that starch solubilisation in 90% DMSO/2 M KOH may be a reasonable method for molecular
characterisation with less AP degradation.