Understanding the role of gluten subunits (LMW, HMW glutenins and gliadin) in the networking behavior of a weak soft wheat dough and a strong semolina wheat flour dough and the relationship with linear and non-linear rheology

The differences in viscoelastic properties of gluten from two very different wheat flours, a weak soft flour dough and a strong semolina dough, primarily caused by their gliadin and glutenin content including gliadin to glutenin ratio were studied. The doughs were subjected to oscillatory time sweep tests at small and large amplitudes as well as small and large frequencies. The gluten subunits (LMW, HMW glutenins and gliadins) tagged with specific fluorescent quantum dots with a distint excitation wavelength were imaged with confocal laser scanning microscopy and their distribution and interactions were measured. The quantitative imaging data was converted into networking data that included lacunarity, network area, and number of network junctions. This networking data was correlated with rheology. The two different dough systems showed different oscillatory behavior during time sweeps. The critical role of LMW glutenins in keeping the structural integrity of semolina doughs was demonstrated by a direct correlation between the non-linear elastic component 'e(3)/e(1)' of the dough and protein network parameters of LMW glutenins. It was also shown that gliadins and HMW glutenins co-localize and associate throughout rheological deformations of the dough. The disruption of the three gluten subunits are responsible for rheological breakdown of soft wheat flour dough, with gliadins influencing the breakdown of the network at higher amplitude deformations. This research presents a new method to analyze the microstructure of wheat doughs and new understanding of how the network structure of the dough subunits contribute and are correlated with fundamental rheological tests.