Synthèse de polymères organiques permettant l'élimination sélective des faux-goûts dans les vins
Responsable du projet à Changins: Dr. André Rawyler
Partenaires : HES-SO Valais (ITV) et EIA-FR (ChemTech)
Financement : HES-SO
The aim of this project is to give to the consumer a rapid, specific, elementary way to eliminate off-flavors in wine.1 to 5% of the world production is victim of organoleptic defects. It means that they can’t be taken out by ventilation. These defects resume in elimination of wines. The most known off-flavor is certainly the cork taint given by the haloanisols. Other compounds for example ethanethiol has an infamous odor of onions or cooked cabbage, geosmin give the earthy taste and a few metabolites of the Brettanomyces yeast like 4-ethyphenol (horse stable), 4-ethylguaiacol (smoky, bacon, spice). Until now, there is no solution to extract off-flavors without loss of naturals wine flavors („thick scalping“).The way studied in this project is to use cyclodextrin (CD) to remove the haloanisols from wine. These molecules, part of the polysaccharides are torus shaped and can encapsulated different kind of molecules. To remove properly CDs from wine once the encapsulation has been done, they need to be linked to a support (grafting) or to each other (crosslinking).
This project leaded to 4 different polymers, caracterized by the linkage and the percent of CD active. Tests on flavors where done by a tasting panel of experts (Engineering school of Changins), to have qualitative data on the effectivness of encapsulation of wine faults and the quantitative results were done in the chemistry analytical department by GC-MS (HES-SO Valais). The conclusion of this project is that CDs are not enough specific to remove cork taint from wine. But with the « Know-How » learned with this project, CDs polymers can be used for various purposes other than those studied in the project. The encapsulation capacity of CDs can be used, for example: (i) Improve the solubilization of a compound in a medium using CDs to synthesize a product from a starting reagent heat-sensitive and poorly soluble, (ii) Separate the enantionmers by column chromatography using a mixture of polymers and silica, (iii) Conduct a SPE column using polymer to concentrate a sample in order to analyze it later on a HPLC. The EIA-Fr is also very active in the development of PLA (Polylactic acid), for this reason, CDs or a mixture of Cd’s polymers and PLA can be created to have additional properties than those already known.