Molecular structure and physicochemical properties of Hylon V and Hylon VII starches illuminated with linearly polarised visible light

Aqueous suspensions (30 g/100 g) of Hylon V and Hylon VII high amylose corn starches were illuminated with linearly polarized visible light for 5, 15, 25 and 50 h. For each native and illuminated starch sample, weight average molecular weight, M_w, and hydrodynamic radius, R_g, of starch polysaccharide molecules were measured by high pressure size exclusion chromatography coupled with multiangle laser light scattering and refractometric detectors (HPSEC-MALLS-RI). Additionally, X-ray diffraction patterns, intrinsic viscosity, kinetic of alpha-amylolysis together with iodine binding properties and distribution of amylopectin structural units were established for each starch sample. Changes in molecular weight M_w of starch polysaccharide chains eluted under whole polysaccharide peaks and values of intrinsic viscosity of corresponding starch samples observed in the course of illumination indicated that illumination of both starches studied, with linearly polarized visible light (LPVL), induced first depolymerysation followed by repolymerisation reaction of starch polysaccharide chains. Illumination induced rearrangements of the molecular structure of polysaccharide chains of illuminated Hylon V and Hylon VII starches led to significant changes of their physicochemical properties as compared with native starches.