Lesław Juszczak

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.

Characteristics of cereal starch granules surface using nitrogen adsorption

Abstract Surfaces of several types of cereal starch granules are investigated using low-temperature nitrogen adsorption. The specific surface, the volume of mesopores and the mean pore diameter are determined using the BET method. Furthermore, pore size distribution, cumulative surface area, volume and mean pore diameter in the range 1.7–300 nm are determined using the BJH method. Surface characteristics and pore characteristics for various cereal starch granules are found to be different.

Phenolic composition and antioxidant activity of propolis from various regions of Poland

The aim of this work was to determine phenolic acid and flavonoid contents, as well as antioxidant properties of propolis from different regions of Poland. Total phenolic content of propolis samples ranged from 150.05 to 197.14 mg/g GAE, while total flavonoid content was 35.64–62.04 mg/g QE. The dominant phenolic acid was p-coumaric acid, the content of which was from 37.54 to 116.95 mg/g. The samples also contained much ferulic acid. Among the flavonoids, chrysine and galangine were dominant, and for two samples, naringine was dominant. The propolis samples exhibited various antiradical activity measured towards DPPH√ (1.92–2.69 mM TE/g) and ABTS√+ (3.96–4.98 mM TE/g) and reducing power was determined by the ferric reducing antioxidant power method (6.23–9.19 mM Fe(II)/g). The significant linear correlations between total phenolic content and antiradical activity and between total phenolic content and reducing power were observed. Moreover, the total flavonoids content significantly correlated with antiradical activity and reducing power.

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 Modified Starches on Rheological Properties of Ketchup

The aim of this work was to study the effect of commercial modified starches of different origin on rheological properties of ketchup. The following starches were used to produce the ketchup samples: chemically modified potato (acetylated distarch adipate from potato starch), waxy maize (acetylated distarch adipate from waxy maize starch and hydroxypropyl distarch phosphate from waxy maize starch), and cassava (acetylated distarch adipate from cassava starch) starches and physically modified cassava and waxy maize starches (physically modified cassava starch and physically modified waxy maize starch). The SEM microphotographs revealed that swollen or disrupted starch granules were present in the ketchup samples. As was evaluated by particle size distribution analysis, two peaks characteristic for different starch granule sizes were observed, the first peak at about 100 μm for ketchup thickened with potato starch and the second one at about 50 μm for the rest of the samples. Ketchups showed non-Newtonian, shear-thinning flow with tendency to yield stress. Values of the rheological parameters describing the flow curves significantly correlated with Bostwick consistency. Ketchup samples exhibited different susceptibility for temperature changes, while values of flow activation energy were from 4.18 to 9.00 kJ/mol. On the basis of mechanical spectra, it is noted that values of G′ were higher than these of G″ showing that elastic properties dominated over the viscous ones. Ketchup samples exhibited properties of weak gels which were estimated from the values of G′ and G″ moduli and their relation and from values of tangent of phase angle (tan δ = 0.14 − 0.37). Principal component analysis revealed both similarities and differences in rheological behavior of the examined ketchup samples thickened with different modified starches.

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.

Hydrocolloids in Forming Properties of Cocoa Syrups

Abstract Agar, carrageenan, carboxymethylcellulose (CMC), and xanthan gum at diversified concentrations were used in coca syrup as stabilizer, thickener, and consistency providers. The syrups obtained in the laboratory conditions were compared to the commercial ones. Sensory evaluation of both commercial and laboratory syrups was comparable, however, the latter obtained slightly higher appraisal. Based on the texture profile analyses (TPA), it was concluded that laboratory and commercial syrups had similar textural properties with one exception. Value of stringiness of laboratory syrups was lower. This factor gave an advantage in evaluation of suitability of these products for consumers, who considered it as more comfortable in use. Rheological properties of syrups were compared by the use of Cassons model. Commercial syrups had yield stress (τ o ) in the range of 0.38–3.74 Pa, and Cassons viscosity in the range of 0.50–3.84 Pa s. Laboratory syrups had more diversified rheological properties. It was also concluded that all selected hydrocolloids (CMC, carrageenan, xanthan gum, and agar) were useful, however to different extent, for cocoa syrups production.

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.