6533b7ddfe1ef96bd1274569

RESEARCH PRODUCT

Le goût moisi-terreux du vin : contribution à la caractérisation cinétique et métabolique des moisissures associées à ce défaut organoleptique

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Some microorganisms that co-exist on the grapevine may have beneficial effects on the quality of wine whereas others may be at the origin of organoleptic deviations. In the last decade, several mouldy or earthy odors have been highlighted in various wine regions from France. (-)-geosmin was found to be the major compound responsible for this deviation, along with Botrytis cinerea and fungi belonging to the genus Penicillium, since they were frequently isolated from “earthy-musty” odor grapes. The extent of damage on the quality of wines, motivated our study on the caracterisation of grape rot fungi. First of all, the microflora of grapes from Burgundy vineyards was identified (morphological and molecular methods), from samples prelevated in 2007. A Penicilium expansum strain (25.03) and two Botrytis cinerea strains (BC1 and BC2) were chosen for further experiments. The validation of a predictive model for the combined effect of temperature and water activity, on the growth of fungi on grape berries, demonstrated that cardinal models with inflexion can be validated on agri-food products, over a wide range of T°C and aw, using the gamma concept. Further we were focused on the influence of copper on the lag time and radial growth rate of moulds in order to better understand copper resistance mechanisms of the fungi and the efficacity of fongicides. The moulds tested showed a great copper tolerance, 4.7 mM for P. expansum and 8.2 and 7.3 mM for B. cinerea strains, BC1 and BC2 respectively. These results motivated our study on the influence of environmental and nutritional factors (T°C, CO2; Cu2+), using a Doehlert matrix, on geosmin production of the fungi tested. Copper (the active component of the “Bordeaux mixture”) showed to be a key factor in the increase of geosmin production by P. expansum.