The Impact of Water Content and Mixing Time on the Linear and Non-Linear Rheology of Wheat Flour Dough

Abstract

The viscoelastic properties of wheat flour dough are known to be very sensitive to small changes in water content and mixing time. In this study the simple scaling law originally proposed by [Rheol. Acta 9, 497-500] to capture the water dependency of the dynamic moduli in small amplitude oscillatory shear, was also applied to creep-recovery shear tests and extensional tests. The scaling law turns out to be valid not only in the linear region, but to a certain extent also in the non-linear region. At sufficiently high water levels, a 'free' water phase exists in dough, which attenuates the starch-starch and gluten-starch interactions. Dough characterisation after different mixing times shows that overmixing may cause a disaggregation or even depolymerisation of the gluten network. The network breakdown, as well as the subsequent (partial) recovery, are clearly reflected in the value of the strain-hardening index, for which a maximum is reached at a mixing time close to the optimum as determined with the Mixograph. Finally, the gluten proteins turn out to be much less susceptible to overmixing in an oxygen-lean environment, which demonstrates the significant role of oxygen in the degradation process.

The time-dependent rheology of fermenting wheat flour dough: effects of salt and sugar

“…5b shows that the extensional viscosity decreases as well, but predominantly for the small strains. These changes in rheological behaviour resemble very closely the rheological impact of an increase in the amount of water used in the dough recipe, which we have studied in a previous publication (Meerts et al, 2017b). When preparing the dough, sucrose is added as an aqueous solution to the wheat flour, while keeping the total amount of water used in the dough preparation the same for all dough samples.…”

“…5b indicates, the dough prepared with sucrose still exhibits a substantial degree of strain-hardening. Changes in the water content do not impair the strain-hardening properties of dough (Meerts et al, 2017b), and so the results obtained in this study seem to point mainly to a volume effect for sucrose.…”

“…Moreover, an insufficient buildup of the gluten network would be readily revealed in the strain-hardening behaviour of dough (as is the case for under-or overmixed dough, see Meerts et al (2017b)), but as Fig. 5b indicates, the dough prepared with sucrose still exhibits a substantial degree of strain-hardening.…”

Disparate dynamic viscoelastic responses of wheat flour doughs coated with different oils for preventing water evaporation during time sweeps and their mechanisms decoupled

“…The linear viscoelastic range was defined as the value of strain, for which storage modulus (G 0 ) has dropped to 95% of the plateau value for small amplitudes (Schiedt et al 2013). According to this definition, the linearity limits of the doughs of 37%, 42% and 47% water content were found to be 0.038%, 0.035% and 0.031%, respectively, which were quite similar to others from 0.01 to 0.08% (Hardt et al 2014;Meerts et al 2017). Subsequently, all time sweep tests were performed at a strain amplitude of 0.02%.…”

“…Dynamic oscillation methods are now intensively used for exploring rheological relations of wheat flour dough with its polymeric protein characteristics (Katyal et al 2018;Singh et al 2011), chemical compositions (Hardt et al 2014;Watanabe et al 2002), network structure (Davidou et al 2008), mixing treatment (Kim et al 2008;Meerts et al 2017) and product quality (van Bockstaele et al 2008). Before conducting an amplitude or frequency sweep measurement in linear viscoelastic range, the first consideration is to determine if the material is stable before data collection.…”