Relaxation dynamics in hydrated gluten networks

• Time-temperature superposition extended the experimental timeframe of observations of gluten relaxation.
• Relaxation behavior of hydrated gluten networks is largely independent of compositional and microstructural differences.
• Most of the stress in gluten, glutenin, gliadin and their mixtures relaxes at very long times.

Stress relaxation in hydrated gluten networks was investigated by means of rheometry and confocal laser scanning microscopy. Stress relaxation was followed for 30 min over a wide temperature range (0–70 °C). Temperature played a significant role in relaxation, allowing the construction of mastercurves and calculation of shift factors. This approach revealed a continuous relaxation with absence of plateau modulus, typical of polydisperse materials of low molecular weight. Calculation of stress relaxation spectra identified three relaxation regimes. Stress relaxation is independent of compositional differences, although, confocal microscopy showed the influence of protein composition on the morphology of the networks. Utilization of concepts from macromolecular dynamics and poroelasticity allowed a first insight to the mechanisms of relaxation. Reptation of chains in combination with water migration from the pores of the network seems to play major role in the relaxation mechanisms. Description of relaxation phenomena under such a theoretical framework allows better understanding of the rheological properties of gluten with the aim to improve its industrial performance.