Wheat Flour Dough Rheology Research Articles

Dynamic rheology of wheat flour dough. I. Non‐linear viscoelastic behaviour

AbstractControlled stress rheometry was used to investigate the effects of starch and gluten fractions on the non‐linearity of wheat flour dough. Flour–water dough showed non‐linear viscoelastic behaviour over all stress values in a cyclic stress sweep. The amplitude‐dependent behaviour of the starch and amplitude‐independent nature of the gluten revealed that starch is responsible for the non‐linearity of the flour–water dough system. Adding starch to gluten caused a substantial narrowing of its linear viscoelastic range.© 2002 Society of Chemical Industry

Dynamic rheology of wheat flour dough. II. Assessment of dough strength and bread‐making quality

AbstractControlled stress rheometry revealed that differences in wheat flour dough strengths could be observed by means of dynamic rheological measurements in the region of higher stress amplitude (ie >100 Pa). At lower stress amplitude (τo) the values of elastic modulus G′ for weak doughs were higher than those for strong doughs, but they decreased substantially beyond 100 Pa stress amplitude (τo), such that the G′ values for strong doughs crossed over the G′ values for weak doughs. Beyond a critical value of stress amplitude (ie 100 Pa), true differences in dough strengths could be seen on the basis of their elastic characteristics, because at large deformations protein–protein interactions played a more dominant role in the rheological behaviour of flour doughs. Dynamic rheological analysis demonstrated a very weak inverse relationship (R2 = 0.16) between the G′ values of flour doughs and loaf volume data for 12 wheat cultivars of diverse bread‐making performance. However, the G′ values of glutens showed significant positive relationships with bread‐making performance, explaining 73% of the variation in loaf volume.© 2002 Society of Chemical Industry

Modelling the Developmental Rheology of Wheat-Flour Dough using Extension Tests

Modern cereal science has progressed to the point where a more detailed and explicit understanding of the rheological properties of wheat-flour dough at the molecular level is required in order to improve plant breeding methodologies, the manufacturing of wheat-flour dough products and the assessment of wheat and wheat-flour quality. The formulation of molecular models provides a basis for predictive tests that can be combined with other protocols. The actual modelling must, in turn, be based on experiments which directly monitor the changing rheology of the dough which occurs during mixing, as it is this evolving rheology which in effect monitors the dough at a molecular level. There are various ways in which this can be done. The perspective adopted here is that, at least on a MixographTM, the mixing of the dough can be viewed as a series of extension tests. It therefore follows that one way to monitor the evolving rheology of a wheat-flour dough during mixing is to perform extension tests on the dough at various stages during the mixing. The results obtained from such experiments are reported in this paper. They show how the study of the evolving rheology of a wheat-flour dough, during mixing with varying amounts of added water, in effect monitors the molecular processes occurring during mixing in terms of the behaviour of the bonded and unbonded water within the dough. In addition, these results yield confirming evidence for the hypothesis, tentatively proposed by various authors, that the bandwidth of a Mixogram is a key (qualitative) characteristic of a dough for assessing its strength. Together, both these conclusions imply that, as well as a measure of the strength and quality of the dough being mixed, the variation in the bandwidth of a Mixogram is indicative of the role played by the added water during the mixing.

LITERATURE ABSTRACTS

LITERATURE ABSTRACTS

LITERATURE ABSTRACTS

LITERATURE ABSTRACTS

Effect of dextrans of differing molecular weights on the rheology of wheat flour doughs and the quality characteristics of pan and arabic breads

AbstractDextrans (α‐1‐6‐D‐glucans) with weight‐average molecular weights (Mw) ranging from 10 to 500 kDa were used at a rate of 20 g kg−1 (flour basis) in order to modify doughs made from flour of the Australian hard‐grained wheat cultivars Banks, Sunco and Hartog. Doughs containing dextran fractions with Mw below 100 kDa showed significant (P ± 0.01) reductions in Farinograph maximal consistency and significant increases in Farinograph development time. Additions of dextrans also resulted in significant increases in maximal resistance and significant reductions in extensibility when doughs were subjected to Extensograph testing. After addition of dextran fractions with Mw of 100 kDa or less, there were significant reductions in loaf volumes in pan bread of the cultivar Hartog manufactured by a rapid dough system and in pan bread of the cultivars Banks and Hartog made by a fermented dough system. Arabic bread supplemented with dextrans had poorer internal and keeping qualities, and reduced bread surface area, leading to significantly decreased quality scores. These observations are discussed in relation to possible interactions between neutral polysaccharides and other flour components.

Comparison of small and large deformation measurements to characterize the rheology of wheat flour doughs

The rheological properties of wheat flour doughs are largely governed by the contribution of starch, protein and water. Starch, the most abundant component in dough (50–55% wt), is in high enough concentration to form a continuous network of particles which gives rise to viscoelastic behavior. Gluten, the protein phase of flour, also has the ability to form a continuous macromolecular network, provided enough water for hydration exists, and sufficient mechanical energy is supplied during mixing. These two independent sources of viscoelastic behavior and their possible interaction make rheological properties of wheat flour doughs difficult to interpret. An attempt is made to uncouple these sources of viscoelastic behavior by careful evaluation of small and large deformation rheological measurements. Two different types of flours and different mixing times were utilized in order to alter the protein phase of the doughs. The results of this study indicate that small deformation, dynamic oscillatory measurements are sensitive to starch-starch, starch-protein, and protein-protein interactions; however, the relative contributions of each of these interactions are difficult to resolve. In contrast, large deformation shear measurements seem to resolve the relative contributions of long-range interactions (protein-protein) and shorter range interactions (starch-starch, starch-protein), to the viscoelastic behavior of wheat flour doughs.

RHEOLOGY OF WHEAT FLOUR DOUGHS

AbstractRheological properties of dough are important since they affect the quality of the baked product. In addition, they are interesting since they provide information on dough structure. Instruments used for quality control in mills and bakeries are reviewed. Experiments at constant stress or at constant rate of deformation are discussed as examples of experimental techniques suitable for description of dough properties in physically simple terms. Relationships between dough structure and rheological properties are also covered.