Mariusz 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.

The influence of acorn flour on rheological properties of gluten‑free dough and physical characteristics of the bread

Manufacture of gluten-free products requires the use of preselected raw materials. The number of such ingredients is limited; therefore, the portfolio of gluten-free bread is less variable and attractive in terms of their appearance, taste and nutritional value in comparison with traditional bread. The aim of the study was to apply debittered acorn flour as a natural nutritional enrichment of gluten-free bakery products and to check its effects on rheological properties of the dough and quality and staling of the bread. The analysis of rheological properties of gluten-free dough supplemented with acorn flour exhibited significant increase in the moduli G′ and G″ and a decrease in phase shift tangent, which denotes firming of dough structure. Introduction of limited amounts of acorn flour caused an increase in bread volume and improved crumb characteristics. In consequence of a diminished starch retrogradation, the respective loaves exhibited slower staling. Bread supplemented with acorn flour exhibited improved sensory acceptance. The obtained results signify that the application of debittered acorn flour in gluten-free baking could be useful for nutritional reasons, as it enriches bread with protein, minerals and dietary fiber, but also because of its technological effects, including structure strengthening, and sensory improvement.

Effect of temperature and soluble solids content on the viscosity of beetroot (Beta vulgaris) juice concentrate.

The study investigates the viscosity of clarified beetroot juice as dependent on temperature and soluble solids content. Rheological research was carried out using a rotational rheometer with a system of coaxial cylinders. Flow curves were obtained in the temperature range from 10 to 60°C and at the soluble solids content of 50° to 67.1°Bx. The concentrate under study showed a Newtonian behaviour. Dynamic viscosity ranged from 5.2 to 320 mPa·s and depended on soluble solids content and temperature of measurement. The effect of temperature was described using an Arrhenius equation. Activation energy values were between 24.68 and 39.96 kJ/mol. The effect of soluble solids content was described employing a power-law function and an exponential function. In addition, two equations were proposed to describe the combined effect of temperature and soluble solids content on the viscosity of beetroot juice concentrate.

Effect of Some Hydrocolloids on the Rheological Properties of Rye Starch

The effect of three non-starch hydrocolloids (guar, carob and arabic gums) on some rheological properties of rye starch pastes/gels at a constant 6.5% concentration of polysaccharides was determined throughout: (i) pasting characteristics, (ii) flow curves and apparent viscosity–shear time curves at 50 C and (iii) mechanical spectra at 25 C. The presence of gums in the system modified the rheological properties of rye starch pastes/gels and these alterations depended on the type and concentration of the gum. The systems with guar and carob gums exhibited higher apparent viscosities during pasting and higher shear stresses during flow than the paste of native starch. The viscosity of the system with carob was bigger than the one with guar gum. The presence of arabic gum decreased the apparent viscosity of the system both during pasting and during flow. Replacing part of starch with a gum modified the viscoelastic properties of gels, the changes depended on the kind and concentration of the gum.

Maltodextrins from chemically modified starches. Selected physicochemical properties.

The aim of this work was to evaluate the effect of chemical modification of starch (cross-linking and/or stabilisation) on selected rheological and functional properties of maltodextrins of dextrose equivalent of 6, 11 and 16. It was found that values of glass transition temperatures were decreasing with dextrose equivalent of maltodextrin. The highest values of glass transition temperature (TG) were determined for maltodextrin of DE 6-obtained from distarch phosphate and acetylated distarch phosphate. Increase in DE value of maltodextrin was also accompanied by decrease and increase in values of intrinsic viscosity and the critical concentration, respectively; however, there was no significant effect of kind of chemical modification of starch on the values of these parameters. Maltodextrin solutions at concentrations of from 10 to 70 % exhibited Newtonian flow behaviour. In the case of 50% solutions of maltodextrins of DE 6 the highest viscosity was produced by maltodextrin from native potato starch, while the lowest one by maltodextrin from acetylated starch. On the other hand, among the maltodextrin of DE 11 this one produced from acetylated starch showed the highest viscosity. All the maltodextrins exhibited surfactant properties in a water-air system, with the strongest effect observed for maltodextrins produced from double chemically modified starches and from acetylated starch. The surface activity was increasing with increasing of the DE value of maltodextrin. Moreover, values of surface tension were decreasing with increasing in maltodextrin concentration in the system.

The retrogradation kinetics of starches of different botanical origin in the presence of glucose syrup

The influence of glucose syrup on the retrogradation of cereal starches was investigated. Laboratory isolated starches from wheat (WS) and oats (OS - oat starch and ROS - residual oat starch) were used in this research. ROS was isolated from the flour left after the industrial separation of β-glucans. Gelatinization temperature of oat starches (63.82°C and 64.01°C for OS and ROS, respectively) was higher than for WS (62.26°C), whereas gelatinization enthalpy for oat starches (8.87J/g and 9.09J/g for OS and ROS, respectively) was lower than for WS (9.99J/g). Moreover, retrogradation percentage (%R) was similar for both oat starches (29.76% and 27.72% for OS and ROS, respectively), and was substantially lower than for WS (42.04%). The introduction of glucose syrup into system reduced the extent of the retrogradation. Rate of the process was suppressed for WS and ROS, whereas for OS it was increased. β-Glucan production process had no significant effect on the gelatinization and retrogradation of oat starch.