Teresa Witczak

Effect of inulin on rheological and thermal properties of gluten-free dough.

The aim of the study was to evaluate the influence of inulins with varying degree of polymerization on rheological and thermal properties of gluten-free starch-based dough. The share of inulin reduced the values of consistency coefficient, as well as storage and loss moduli, and increased creep compliance. Inulin preparation with the highest average degree of polymerization had the strongest impact on viscoelastic properties of the obtained dough. The presence of inulin also caused a significant decrease of viscosity upon pasting, and an increase of gelatinization temperatures TOg, TP1g, TP2g, and TEg. Addition of inulin had no effect on gelatinization enthalpy (ΔHg), while it strongly reduced the enthalpies of retrograded amylopectin after storage. Water binding properties of inulin seem to be the key factor, responsible for modification of dough properties, because they influence solvent availability for other constituents of such system.

Effect of Maltodextrins on the Rheological Properties of Potato Starch Pastes and Gels

The study examines the effects of maltodextrins saccharified to various degrees on some rheological properties of potato starch dispersions. Pasting characteristics, flow curves, and mechanical spectra were determined for native potato starch and for its blends with potato maltodextrins having dextrose equivalents (DE) of 10.5, 18.4, and 26.5. The results showed that medium-saccharified maltodextrin (DE = 18.4) gave the strongest effect, manifesting itself as a considerable reduction in the viscosity at pasting, a decrease in apparent viscosity during flow, and a decrease in the storage and loss moduli. Addition of high-(DE = 26.5) or low-(DE = 10.5) saccharified maltodextrins had a markedly smaller effect on the rheological properties of starch. The differences in the effects produced by the maltodextrins are closely connected to the degree of polymerisation of the maltooligosaccharides in the systems.

Characterization of Some Spelt Wheat Starches as a Renewable Biopolymeric Material

The aim of this work was to analyze selected physical, chemical, thermal, and rheological properties of starches isolated from different spelt wheat varieties. The analyzed starches contained from 22.5 to 24.6 g/100 g of amylose and from 45.9 to 50.6 mg/100 g of phosphorus. Ranges of characteristic gelatinization temperatures, , , and , were 55.7–58.5°C, 61.1–62.6°C, and 67.4–68.2°C, respectively, while gelatinization enthalpy ranged from 8.87 to 9.96 J/g. The pasting curves showed significant differences in pasting characteristics of the starches. The values of maximum viscosity () and viscosity after cooling () determined for the starch pastes were in the range of 82.3–100.7 B.U. and 149.3–172.7 B.U., respectively. The starch pastes demonstrated non-Newtonian, shear thinning flow behaviour and thixotropy phenomenon. After cooling the resulting starch gels were characterized by different viscoelastic properties, with a dominance of elastic features (). The starches exhibited different tendency to retrogradation, with its degree () in the range of 21.1–37.4%.

Liquid-Phase Esterification of Methacrylic Acid with Methanol Catalyzed by Heteropolyacid

The esterification kinetics of methacrylic acid with methanol in the presence of H3PW12O40 or H3MoW12O40 as a catalyst was studied with isothermal batch experimental. The catalyst concentration was varied between 14.4 and 57.7 mol/m3. The experiences were carried out at temperatures from 316 to 333 K and initial molar ratios of the reactants from 3 to 10. The non-ideality of the liquid phase was accounted for by using activities instead of molar. The activity coefficients were determined using the UNIFAC method. The kinetic equations developed had a non-elementary form, and the order of the reaction was a fraction.

Sorption properties of modified potato starch

Background. Starch is one of the biopolymers most commonly used in the food industry. In its native form its applications are limited. In contrast, its structure is relatively readily modified using various methods, producing starch derivatives of greatly diverse properties. The primary methods used to change characteristics of starch include acetylation and oxidation. Thus obtained raw materials are used as food additives. Stability of these raw materials and food products to a considerable extent depends on their composition and parameters characterizing storage facilities, i.e. relative humidity and temperature. One of the methods to specify adequate ambient conditions is based on water activity supplemented by sorption isotherms. As a result studies investigating correlations between water activity and moisture content are of importance for the optimization of storage conditions and design of certain food processing procedures. For this reason the aim of this study was to assess the effect of modification (oxidation, acetylation and their combination) on sorption properties (described based on sorption isotherms) of potato starch. Material and methods. Analyses were conducted on potato starch and its derivatives produced by acetylation, oxidation and co-modification (acetylation coupled with oxidation). Starch was oxidized using sodium chlorate (I), while acetylation was run using anhydrous acetic acid. Sorption isotherms were determined by the static desiccator method. Results were described applying selected mathematical methods equipped with physical interpretations (BET and GAB) and empirical models (Halsey, Oswin, Henderson, Pelega, Lewicki, Blahovec-Yanniotis). Calculations were made using non-linear estimation.

The influence of the catalyst on the kinetics of ethyl metacrylate synthesis

The influence of the catalyst on the kinetics of ethyl metacrylate synthesis The synthesis of ethyl metacrylate in the liquid phase was studied. Tungstophosphoric and molybdophosphoric acids, which belong to heteropolyacids group, were used as a catalyst. The chemical compounds from this group are often utilized in the catalysis with regard to their activity and selectivity. The rate equations, reaction rate constants and equilibrium constants have been determined. The reaction order and the kinetic parameters of the kinetic relations were determined by the integral method. All rate equations are formulated with activities taking the non ideal effects of the compounds into consideration. It was found that the kinetics of the esterification of the presented reactions was non-elementary