2022, Makowska, Agnieszka, Dwiecki, Krzysztof, Kubiak, Piotr, Baranowska, Hanna Maria, Lewandowicz, Grażyna

Starch paste is a very complex dispersion that cannot be clearly classified as a solution, colloid or suspension and many factors affects its properties. As these ambiguities constitute a barrier to technological development, the aim of this study was to investigate the interaction of starch macromolecules with water by analysing the results of rheological properties, low field nuclear magnetic resonance (LF NMR), dynamic light scattering (DLS) and ζ potential analyses. Starch pastes with a concentration of 1%, prepared with distilled water and buffered to pH values of 2.5, 7.0 and 9.5 were analysed. It was proved that the pH buffering substantially decreased the values of consistency index but the pH value itself was not significant. LF NMR studies indicated that the dissolution of starch in water resulted in a reduction in spin-lattice as well as spin-spin relaxation times. Moreover, changes in relaxation times followed the patterns observed in rheological studies. Electrokinetic and DLS analyses showed that potential values are primarily influenced by the properties of the starches themselves and, to a lesser extent, by the environmental conditions. The conducted research also showed complementarity and, to some extent, substitutability of the applied research methods as well as exclusion chromatography (a method not used in this work).

2022, Śmigielska, Hanna, Błaszczak, Wioletta, Lewandowicz, Grażyna

Growth in the human population and intensive, large-scale farming results in a lowering in the quality of nutrition. An oversupply of food energy is often accompanied with a deficiency in micronutrients. To address this problem, the food industry provides products enriched with bioactive substances. The main challenge of this technology is the even distribution of micronutrients in the matrix of the fortified food. A possible solution to this challenge is to use stable and effective carriers. The aim of this work was to verify the applicability of native potato starch and modified starches (commonly used in the food industry) as carriers for microelements. Adsorptions were carried out in starch suspensions at a temperature below gelatinisation. The native potato starch and the modified starches (E 1404, E 1412, E 1420, and E 1422) were assessed for their effectiveness in adsorbing copper, iron, and zinc sulphates or gluconates. Pasting characteristics were analysed using a Brabender viscograph and light microscopy. Furthermore, texture profile analysis of starch-based desserts was carried out with the use of the tested carriers. Starch in both its native and modified forms was able to effectively adsorb copper, iron, and zinc ions. Adsorption was more efficient when using modified starches containing hydrophilic carboxyl groups. The effectiveness of adsorption with oxidised starches increased with an increase in the degree of substitution. Starches containing more hydrophobic acetyl groups were less effective as adsorbents of microelements. The cation adsorption efficiency decreased in the order copper > iron > zinc, and sulphates were better adsorbed than gluconates. Copper ions influenced the pasting characteristics of the oxidised starches, and these effects were dependent on the degree of substitution with carboxyl groups. As observed by light microscopy, the presence of copper ions changes the interaction between the starch macromolecules and water. However, the above-mentioned changes did not significantly affect the texture of traditional sweet desserts. Starch, particularly its oxidised derivatives containing hydrophilic oxidised groups, can be recommended as a carrier of microelements for food fortification. The use of modified starches containing relatively hydrophobic acetyl groups is not appropriate because they absorb microelements less efficiently than native starch.