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- Model gluten gels

Auteur(s): Ramos L.

Conference: Physics in Food Manufacturing (Edinburgh, GB, 2018-01-10)


Résumé:

The origin of the unique rheological properties of wheat gluten, the water-insoluble protein fraction of wheat grain, is crucial in bread-making processes and questions scientists since the 18th century. Gluten is a mixture of two types of proteins, monomeric gliadins and polymeric glutenins, formed by subunits linked via disulfide bonds. To better understand the respective role of gliadins (Gli) and glutenins (Glu) in the supramolecular structure of gluten and its link to rheology, we have developed a model gluten system using a food-grade solvent, which allows quantitative comparisons with theoretical models for synthetic polymers [1]. Thanks to an experimental protocol based on a liquid-liquid phase separation, we can extract, from industrial gluten, gluten protein fractions with contrasted mass ratios Glu/Gli (from 0.04 to 2). Stable gluten protein suspensions in a water/ethanol mixture solvent over a wide range of concentrations can be produced. Using scattering techniques, we demonstrate that blends of Gli and Glu exhibit features characteristic of branched flexible polymer chains in a good solvent, and form in a dilute regime large Glu-rich protein assemblies [2]. In the semi-dilute regime, we evidence the existence of large zones (of typical size 60 nm) rich in hydrogen bonds [3]. We show that hydrogen bonds are responsible for the spontaneous sample gelation, whose concentration dependence can be quantitatively accounted using percolation theories developed for polymer gels [4]. Overall, our experimental results illustrate the relevance of model gluten gels to unravel the unique and complex behavior of gluten. [1] Banc, Dahesh, Wolf, Morel, Ramos. Journal of Cereal Science 75, 175 (2017). [2] Dahesh, Banc, Duri, Morel, Ramos. J Phys Chem B 118, 11065 (2014). [3] Banc, Charbonneau, Dahesh, Appavou, Fu, Morel, Ramos. Soft Matter 12, 5340 (2016). [4] Dahesh, Banc, Duri, Morel, Ramos. Food Hydrocolloids, 52, 1 (2016).