Rechercher
2011 : an exceptional vintage
Seated at the Bistrot des Amis, you approach your lips to a glass of red wine, with its translucent robe and delicate aromas. Your senses alert, the chemistry gets under way : the molecules that make up the wine (tannins) and those from the saliva (proteins) recognise each other and form a supramolecular edifice. Their union leads to a change in the lubrication of the palate and causes a sensation of dryness and shrinkage of the mucous membranes, characteristic of astringency.
The chemists from Bordeaux have brought their expertise together to "make" the raw material, the proteins from saliva and the tannins, and develop an exceptional tool : nuclear magnetic resonance. The objectives : understanding the behaviour of tannins in the wine (their sociability, in a way, which will depend on their number), and visualising their combinations with the proteins from saliva by observing the change in size of the tannin-protein complex.
The study of these associations was carried out on tannins of the same size with intimate structures that are neither perfectly identical nor radically different, and also on tannins with identical chemical properties but with different sizes. Despite the very strong similarity shown by the plane chemical structures of the tannins under study, each one of them adopts its own spatial structure and a specific affinity towards the proteins from saliva.
Thus, from one grape variety to another, from one year to another, from one wine to another, a difference in the composition of tannins may result in the formation of a greater or lesser number of tannin-protein complexes, which would explain the different sensations in the mouth.
- Institut des sciences moléculaires, CNRS-Universités Bordeaux 1 et 4-ENSCP Bordeaux
- Chimie et biologie des membranes et des nanoobjets, CNRS-Université Bordeaux 1-ENITA
- In vitrum veritas (extrait)
Réalisation : Claude Delhaye et Christophe Gombert - Production : CNRS Images (2009)
Facebook
Twitter