Evidences of amylose coil-to-helix transition in stored dilute solutions

Static (SLS) and dynamic (DLS) light scattering measurements were performed in order to study the conformational changes in amylose during storage in alkaline (KOH) and briny (KCl) aqueous solutions. Immediately after dissolution, amylose was structured as random coil and the polymer architecture was not affected by the electrolyte concentration. In stored samples the electrolyte concentration played a more important role. Although no general trend for the radii variation, depolymerisation process was not detected and an increase in the scattered light depolarization ratio was evidenced, being more pronounced for amylose chains stored in KOH. This behavior was attributed to a coil-to-helix transition in the amylose chains. Hence, the presence of precipitation after ∼30 days of storage suggests the helix amylose crystallization.