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This study was aimed at establishing the effect of saturating starches from different botanical origins with iron ions on selected physicochemical properties of the resulting modified starch. Native and modified starches were determined for amylose, protein, fat, and phosphorus content as well as water binding capacity and solubility in water. In addition, the number of iron ions was assayed by atomic absorption spectroscopy (AAS). The thermal properties of samples were also examined using a differential scanning calorimeter (DSC). Flow curves were plotted and described using the Ostwald de Waele model, and the degree of paste structure recovery was determined. Samples enriched with iron ions were treated thermally and radical generation in the starch structure was assayed by means of electron paramagnetic resonance (EPR). AAS analysis proved the presence of iron ions in the investigated modified starch preparations. The results achieved established that enriching starch with iron ions affected the rheological and thermal properties of starch preparations. However, the extent and nature of these changes depended on the botanical origin of the starch. This was also a factor in the thermal generation of radicals, a process, which appeared to be more effective in potato starch preparations.

Influence of enrichment with ions from alkali (K), alkali-earth (Mg) and d transition (Cu, Fe) metal groups of native and modified starches on the process of carbohydrate radicals generation has been studied using electron paramagnetic resonance (EPR) spectroscopy. This technique allows following the character and amount of created radicals, as well as the changes in coordination sphere of transition metal ions incorporated into starch matrix. The main difference between transition metal ions and the ions of alkali and alkali-earth metals consisted in the character of their interactions with functional groups of starch. Transition metal ions coordinated glucose units of starch and influenced the mechanism of carbohydrate radical formation independently of the kind of starch modification. Interaction of starch, native and modified, with ions of alkali and alkali-earth metals did not change the mechanism of radical generation, however, influenced their number. Contents of total metal ions found analytically by spectroscopic methods and by EPR allowed determination of the amount of transition metal ions engaged in interactions with starch matrix, as well as the differentiating of native and modified starch in respect of their metal ions adsorptive ability.

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