How the biodegradability of wheat gluten-based agromaterial can be modulated by adding nanoclays

IATE Axe 2 : Structuration sous contraintes des agropolymères et réactivité des poudres Contacts : fax: þ33 4 6714 4990 ; email adresses : anne.chevillard@univ-montp2.fr, helene.coussy@univ-montp2.fr, cuq@supagro.inra.fr, guillard@univ-montp2.fr, cesar.guy@neuf.fr, gontard@univ-montp2.fr, egastald@univ-montp2.fr; The objective of this work was to investigate the influence of clay nanoparticles on the biodegradability of wheat gluten-based materials through a better understanding of multi-scale relationships between biodegradability, water transfer properties and structure of wheat gluten/clay materials. Wheat gluten/clay (nano)composites materials were prepared via bi-vis extrusion by using an unmodified sodium montmorillonite (MMT) and an organically modified MMT. Respirometric experiments showed that the rate of biodegradation of wheat gluten-based materials could be slowed down by adding unmodified MMT (HPS) without affecting the final biodegradation level whereas the presence of an organically modified MMT (C30B) did not significantly influence the biodegradation pattern. Based on the evaluation of the water sensitivity and a multi-scale characterization of material structure, three hypotheses have been proposed to account for the underlying mechanisms. The molecular/macromolecular affinity between the clay layers and the wheat gluten matrix, i.e. the ability of both components to establish interactions appeared as the key parameter governing the nanostructure, the water sensitivity and, as a result, the overall biodegradation process.