Unravelling the relationships between wheat dough extensional properties, gluten network and water distribution

Abstract

Wheat flour doughs were prepared from four commercial wheat flours at different mixing times and hydration levels in order to obtain variations in their rheological properties and gluten network structure. Their rheological behavior was assessed by Dynamic Mechanical Analysis (DMA) for their viscoelastic properties and by Lubricated Squeezing Flow (LSF) for their extensional properties. Gluten network structure was determined by quantitative analysis of confocal microscopy (CLSM) images. Among the rheological properties, the consistency index (k) derived from the extensional viscosity and the elastic modulus ratio (E′Max/E′Min) varied between 10 and 42 kPa.sn, and 4 and 26, respectively. They were found to be consistently linked to the gluten network structure. This structure was primarily described by the morphological descriptor, “protein width”, which defines the thickness of protein strands, the average value of which varied between 1.7 and 2.5 μm. Both rheological properties and morphological criteria were significantly influenced by dough hydration rather than by mixing time, whereas the flour characteristics did not play a major role. Interpretation of these results, supported by previous 1H time domain nuclear magnetic resonance (TD-NMR) results concerning water distribution profiles, showed that an optimal dough is defined by a high dough consistency index (k) and a highly cross-linked gluten network (low E'Max/E'Min ratio), presenting thin protein strands.