How natural variability of gluten and arabinoxylans drives wheat dough extensional properties

This study investigates the influence of proteins and arabinoxylans contents of wheat grain on the dough extensional properties, critical determinants of bread quality. Thirty-seven wheat samples (37) were selected from an initial set of 150 wheats, according to technological criteria, including water absorption (WA), to assess the impact of natural variability of several protein and arabinoxylan (AX)-related features on dough behaviour. Dough were prepared at the hydration level determined by the WA Farinograph tests. TD-NMR results showed that, for all samples, the dough reached an optimal hydration state, reflected by a four-peak time distribution. Rheological tests were performed on dough samples at low deformation with Dynamic Mechanical Thermal Analysis (DMTA), and at large deformation, using Lubricated Squeezing Flow test (LSF). Results indicate that the maximum storage moduli E’max determined by DMTA, at temperature close to 70°C, is primarily influenced by initial gluten network cross-linking. E’max decreased between 1.1 MPa to 0.6 MPa, with increasing wet gluten content from 17.2 to 40 g/100g. At large deformation, the extensional viscosity of all doughs followed a power law, from which was derived the consistency index K. Surprisingly, K increased from 11,100 to 22,200 Pa.sⁿ when the intrinsic viscosity of water extractable arabinoxylans increased from 420 to 820 mL/g, n being the flow index of the dough. Results showed that the extensional viscosity is more closely affected by the AX characteristics than by protein characteristics. These results were interpreted in terms of supramolecular distribution of the gluten network and the entangled arabinoxylans in the liquid phase, and discussed for their possible impact on bread making for a wide range of wheats.

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