EN
Native starches, such as potato, wheat, maize, and waxy maize, were subject to oxidation with sodium chlorate(I), hydrogen peroxide in the presence of Cu2+ ions, and sodium chlorate(III) in the presence of formaldehyde. Native starches and their modified preparations were determined for the content of carboxyl and aldehyde groups. In order to determine changes in the internal structure of starch granules, thermodynamic characterization of phase transitions (DSC) was taken and the degree of crystallinity with X-ray diffractions was determined. Potato starch, after oxidation with the applied reagents, became slightly more crystalline, while cereal starches were affected very little. The thermodynamic gelatinization indices obtained for oxidized starches were only changed a small amount in comparison to native ones, which means that the internal structure of the granules is almost unaffected by oxidation.