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This study was aimed at determining the effect of starch oxidation on its acetylation, structure of starch granules, and generation of free radicals. Corn and waxy corn starches were oxidised by NaClO applied in doses of 10, 20, and 30g Cl/kg of starch, and then acetylated using acetic acid anhydride. The carboxyl, carbonyl, acetyl groups were determined in modified starches. Structural properties of starch granules were evaluated based on molecular weight distribution, gelatinisation, crystallinity, specific surface, intrinsic viscosity. EPR measurements were carried out to establish starch susceptibility to UV irradiation induced generation of free radicals. It was found that the number of carbon centered radicals was dependent on the kind of starch and its chemical modification. Study results allowed concluding that the applied modifications contributed to significant changes in starch granules that were determined not only by the amylose content of starch but also by the degree of its oxidation., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

This study was aimed at determining the effect of the amylose content of starch and oxidation level of potato starch on the structure of starch granules, and susceptibility to chemical modification (acetylation) and subsequent generation of radicals. Potato starch and waxy potato starch were oxidised with sodium hypochlorite applied in doses corresponding to 10, 20, and 30gCl/kg starch, and then acetylated with acetic acid anhydride. The carboxyl, carbonyl, acetyl groups were determined in modified starches. Structural properties of starch granules were evaluated based on gelatinisation, crystallinity, specific surface, intrinsic viscosity, and microphotographs by SEM microscope. The electron paramagnetic resonance (EPR) measurements were carried out to establish starch susceptibility to radical creation upon chemical modification and UV radiation. The amount of formed radicals was treated as a measure of the starch structure stability. The higher amount of amylose and the highest level of oxidation led to strong starch structure destruction and consequently facilitated radical generation. Study results showed also that amylose content as well as the degree of starch oxidation modified consecutive acetylation process. The different effectiveness of the acetylation processes influenced the morphology and structure of starch granules., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Abstract: The aim of this study was to analyze the influence of chemically modified starches (HDP and ADA) and high amylose corn starch (HACS) on the rheological and thermal properties of gluten-free dough based on corn and potato starches with pectin and guar gum. The results indicate that the dough with the addition of modified starch behaves as weak gel, the value of storage modulus G′ significantly depends on the frequency and the values of tan δ = G″/G′ range from 0.32 to 0.49. Significant influence of hydroxypropylated distarch phosphate (HDP) on the viscoelastic properties of dough was observed. The share of modified starch in the system caused a decrease of the instantaneous and viscoelastic compliance. It also influenced the retardation time and zero shear viscosity. The application of modified starches (HDP and ADA) for dough preparation did not have much impact on the pasting characteristics. However, significant reduction of the onset and end viscosities were found for high amylose starch (HACS). Thermograms obtained for individual dough systems were characterized by the presence of two peaks, associated with the existence of two different starches in the system. No significant effect of modified starch on the onset temperature (T O) and only a slight effect of HACS starch on gelatinization enthalpy were observed. However, the level of addition of individual starch affected peak and end (T E) temperatures, depending on the type of preparation. [Copyright &y& Elsevier]

The aim of this study is to evaluate the effect of potato protein (PP) on thermal and rheological characteristics of maize starches with different amylose contents. Samples are prepared by substituting 0, 1, 2, or 3 parts by weight of PP for 10 parts by weight of high amylose (HA), common (CM), or waxy (WM) maize starch. The PP has a different influence on the gelatinization characteristics of starch. Gelatinization enthalpy of the CM and WM starches increases from 12.08 to 21.76 J g–1 and from 16.95 to 25.62 J g–1, respectively, when the highest amount of the PP is used. Pasting temperature of the HA and CM starches decrease by 0.3–1.56 °C and 0.43–3.60 °C, respectively, while that of WM starch remains unchanged. The HA starch–PP pastes show higher final viscosity (736 × 10–3–2123 × 10–3 Pa s) than the starch‐only paste (580 × 10–3 Pa s). The starch‐protein pastes exhibit a shear‐thinning flow and a phenomenon of thixotropy. Substitution of the part of the HA or CM starch with the PP result in weakened viscoelastic structures of the produced gels, while the WM starch gel structure is strengthened. Results of the study may be useful in designing maize starch‐based foods supplemented with potato protein. [ABSTRACT FROM AUTHOR]

The objective of this study is to determine the effect of oxidation level on susceptibility to acetylation, molecular structure, and functional properties of high‐amylose corn starch. High‐amylose corn starch is oxidized with sodium hypochlorite (equivalent 10, 20, 30 g Cl kg−1 starch) and acetylated with the acetic acid anhydride. Content of carboxyl, carbonyl, and acetyl groups; molecular size distribution, XRD spectra, specific surface, and morphology are determined in starches. Water‐binding capacity and solubility in water are also measured. Susceptibility of starch to the formation of stable organic radicals upon UV irradiation is detected with the EPR spectroscopy. The level of the oxidation of high‐amylose starch has a great impact on acetylation and on changes in starch structure. It is found that acetylation increases water binding capacity and water solubility of oxidized starches. High‐amylose corn starch exhibit strong susceptibility to radical formation which results from the fact that the liability of its structure is higher than that of normal and waxy ones. Modification processes prevented the destruction of starch against UV irradiation. This study investigates the effect of oxidation level on the susceptibility to acetylation, molecular structure and functional properties of high‐amylose corn starch. The level of the oxidation of high‐amylose starch has a great impact on acetylation and changes in molecular structure. Acetylation increases water binding capacity and solubility in water of oxidized starches. [ABSTRACT FROM AUTHOR]