Effect of Phosphorylation and Copper(II) or Iron(II) Ions Enrichment on Some Physicochemical Properties of Spelt Starch

ABSTRACT:

This paper provides an assessment of the effect of saturation of spelt starch and monostarch phosphate with copper or iron ions on selected physicochemical properties of the resulting modified starches. Native and modified spelt starch samples were analyzed for selected mineral element content using Atomic Absorption Spectroscopy (AAS). Thermodynamic properties were measured using DSC, and pasting properties by RVA. Flow curves of 5% pastes were plotted and described using the Herschel-Bulkley model. The structure recovery ratio was measured. AAS analysis established the presence of iron(II) and copper(II) ions in the samples of modified starches and that potassium and magnesium ions had leached from them. In comparison to unfortified samples, enriching native starch with copper(II) ions decreases value of all temperatures of phase transformation about 1.3-2.7 °C, but in case of monostarch phosphates bigger changes (2.8-3.7 °C) were observed. Fortified native spelt starch with copper(II) ions caused increasing the final viscosity of paste from 362 to 429 mPa·s. However, presence iron(II) ions in samples caused reduced its final viscosity by 170 (spelt starch) and 103 mPa·s (monostarch phosphate). Furthermore, enriching monostarch phosphate contributed to reduce degree of structure recovery of pastes from 70.9% to 66.6% in case of copper(II) ions and to 59.9% in case of iron(II) ions.

Key words:
chemically modified starch; enrichment; phosphorylation; spelt starch