Authors:Karina Ilona Hidas, Csaba Németh, Anna Visy, Adrienn Tóth, László Ferenc Friedrich, and Ildikó Csilla Nyulas-Zeke
. Herald et al. (1989) examined the rheological behaviour of heat-treated liquid whole egg at −24 °C for 80 days. Thixotropic behaviour was found in all samples examined, and their rheologicalproperties were completely altered, with near Newtonian
Authors:B. Bogdanov, E. Schacht, and A. Van Den Bulcke
Hydrogels prepared by crosslinkage of gelatin with dextran dialdehyde have been characterized by dynamic shear oscillation
measurements at small strain. Isothermal as well as temperature scan measurements were performed. The results obtained demonstrated
that the final polymer network is a result of a chemical gelatin-dextran dialdehyde interaction as well as a gelatin-gelatin
(physical association) and a polymer-solvent interaction. This balance is strongly dependent on the composition of the system,
the polymer concentration, the storage temperature and the storage time.
We found that a short cryogenic treatment at −20°C of physically structured gels, significantly increases the chemical crosslinkage.
DSC measurements at low cooling rate confirm these results and demonstrate a chemical reaction enthalpy contribution.
Authors:M. Oszvald, S. Tömösközi, L. Tamás, and F. Békés
Structure and composition of wheat storage proteins and functional properties of wheat gluten are well studied; therefore several methods and instruments are available to determine these properties. The investigation of functional properties of rice proteins, depending on the different goal of utilisation, has not been well established, yet. In this study, the rheological properties of four varieties of rice flour were studied using a 50 g Farinograph demonstrating the mixing properties of rice flours and the alterations of these properties caused by the supplementation of wheat proteins. The considerable differences identified on the mixing curves of different rice flours indicate that the investigation of mixing properties can be one of the useful approaches for the characterisation of functional properties of rice dough. The large effects of the addition of wheat gluten on the mixing properties of rice flours demonstrate the possibility of using rice flour and dough as a wheat protein free model system for the in vitro investigation of the functional roles of wheat storage proteins.
Authors:A. Lambert-Meretei, E. Szendrei, M. Nogula-Nagy, and A. Fekete
The aim of the work was to develop a method to evaluate the effect of bread improver dosage on bread crumb texture. Standard breads were prepared to get different crumb structures when bread improver was added to the flour in a concentrate of 0.2%, 0.4% and 0.6%. The additive used in the experiments contains lecithin, ascorbic acid and alpha-amylase. Rheological tests and image analysis were performed to predict the effect of the additive. Hardness, chewiness, gumminess, cohesiveness and springiness were determined by rheological method. The rheological properties neither separately nor combined were able to discriminate the different bread crumb groups. Image processing method was developed to determine the ratio of dark to light area of the images taken of the bread slices. It was concluded that both rheological and visual parameters should be taken into account to characterize bread crumb texture.
Authors:M. Sabo, M. Sabo, D. Jug, D. Jug, Ž. Ugarčić-Hardi, and Ž. Ugarčić-Hardi
The effect of tillage systems (TS) on wheat quality traits including grain yield, thousand-kernels weight, hectoliter mass, flour extraction rate and flour rheological properties were evaluated. Five different TS were compared in winter wheat (Triticum aestivum L.) production on one experimental field (chernosem) located in the Baranya region, north-eastern Croatia from 1998 to 2001. Tillage systems included conventional tillage (CT), disc harrowing, fine till (DHF), soil loosening (SL) + disc harrowing (DH), disc harrowing, coarse till (DHC) and no-tillage (NT). The most stable grain yield was obtained by DHF and CT in all three experimental years. There was no striking regularity with regard to applied TS and hectoliter mass and thousand-kernels weight. The biggest difference of hectoliter mass was determined between CT and NT. TS had significant influence on the flour extraction rate in all three experimental years. The influence of TS on farinographic parameters was significant for all three experimental years for the quality number. Quality number was greater under CT than under other TS. Tillage effect on extensographic and amylographic parameters in the 3-year average did not show statistically significant differences. To sum up, since disc harrowing (DHF) and (DHC) followed by soil loosening with chisel produced equal grain yield and wheat quality parameters were slightly better than conventional tillage, these systems could be presented as an even handed replacement for ploughing.
The high concentration 17 wt% triblock copolymer poly(ethylene oxide)100–poly(propylene oxide)65–poly(ethylene oxide)100 Pluronic F127 aqueous solutions with the addition of laponite is investigated as a novel temperature-sensitive hydrogel system.
The critical micelle temperature (cmt) and the sol-to-gel transition were characterized by rheological experiments and differential
scanning calorimetry. Experimental results showed that laponite particles have no significant influence on the cmt. On the
other hand, viscoelastic measurements have highlighted an increase of the sol-to-gel transition temperature for mixtures with
2 and 3 wt% of laponite particles. This additive can be used to adjust the gelation temperature close to physiological temperature
in medical applications.