Investigation of stress relaxation in hydrated gluten networks using spectral analysis

Gluten and its protein fractions were isolated from wheat flour. Stress relaxation in hydrated gluten, its protein fractions and varying percentage mixtures of the components were investigated by means of rheometry and confocal laser scanning microscopy. Stress relaxation was carried out over a period of 30 min at 20 °C for all samples under investigation. Samples exhibited relaxation modulus G(t) ranging from 1 to about 1000 Pa with the gliadin fraction showing almost full decay. MATLAB with the combination of regularization algorithms were used to generate L-curves and calculate the relaxation spectra of the samples. Stress relaxation spectra identified five dominant relaxation modes with baseline resolution. Stress relaxation is somewhat independent of compositional differences, although, confocal microscopy showed the influence of protein composition on the morphology of the networks. Therefore, morphology and relaxation dynamics seem to be controlled by independent mechanisms for gluten networks. These findings provide a fundamental understanding of gluten dynamics and may allow controlling the industrial performance of flours and engineering novel dough formulations.