Changements de structure associées aux variations de température et d'hydratation des produits céréaliers suivis par RMN à bas champ

Abstract

International audienceBased on spin-spin T2 relaxation time measurements, the time-domain NMR (TD-NMR) spectroscopy has been used to provide relevant information on the water and biopolymer motion and transfer in bread. This technique permits to characterize molecular interaction and transformations in a non-invasive and non-destructive way, in real time during a process (heating, freezing, hydration ...). In bread, proteins of gluten when hydrated form a viscous mass that confers to the dough, structure, viscosity, mixing tolerance and gas holding ability. On the other hand, starch, in presence of water and increasing temperature, undergoes a series of changes known as swelling, gelatinization and retrogradation that induce variations in water distribution, in starch structure and interactions between them. Our studies aims at understanding and ranking the contribution of these biochemical transformations that contribute to the crumb structure and the textural properties of bread made with cereal flour or a gluten free mix. The water transfers and the extent of starch gelatinization in dough and crumb were studied by TD-NMR during and after the heating/cooling process of dough at various water levels. Preliminary fast field cycling NMR experiments make it possible to envisage further works in order to understand the role of water in the formation of bread crumbs