Identification des dérives terpéniques dans les raisins de certaines variétés de Vitis vinifera ; I- Techniques expérimentales

AUSTERWEIL (1946) a émis le premier l'hypothèse que l'arôme de muscat serait dû au linalol ou à ses dérivés. Dans un travail fondamental resté classique, CORDONNIER (1956) montre que les extraits par l'éther de pétrole d'un vin de muscat présentent' des taches dont les Rf et les réactions colorées avec l'acide sulfurique concentré laissent supposer la présence de limonène, de linalol, de géraniol et d'α-terpinéol dans la composition de l'arôme de ce type de vin. BAYONOVE et CORDONNIER (1970 a et b) confirment la présence du linalol dans différents Muscats : Alexandrie, Hambourg, Frontignan, Fleur d'Oranger, Ottonel, Reine des Vignes ; ils montrent également l'absence de ce corps, tout au moins en quantité notable, dans le Cabernet-Sauvignon, le Merlot, le Syrah, le Piquepoul et le Chasselas

An odour detection threshold determination of all four possible stereoisomers of oak lactone in a white and a red wine

Copyright © 2008 Australian Society of Viticulture and Oenology Inc.Odour detection thresholds were determined for all four stereoisomers of oak lactone in both red and white wine. The natural cis-isomer was found to have a significantly lower detection threshold than its non-natural enantiomer in both media, and lower than indicated by most other sensory studies. The odour detection threshold for the natural trans-isomer was seven times higher than for the natural cis. Compared to its enantiomer, the natural trans-isomer had a lower detection threshold in the white wine medium, but slightly higher in the red. Duo-trio difference testing between the two trans-isomers added at the same concentration showed no significant difference between the two for both media. Similarly, a duo-trio test conducted between the natural cis-isomer and a mixture of the same amount of natural cis-oak lactone plus an equivalent concentration of the trans-isomer indicated that the latter had little or no influence on the odour impact of the cis-form.Rachel C. Brown, Mark A. Sefton, Dennis K. Taylor and Gordon M. Else

Review: Steam distilled spirits from fermented grape pomace Revision: Bebidas destiladas obtenidas de la fermentación del orujo de uva

Grape pomace is the solid residue left after juice extraction from grapes, and represents in Mediterra nean countries the most important by-product of the winemaking industry. Steam distillation of fer mented grape pomace will eventually produce a spirit, designated as bagaceira in Portugal, orujo in Spain and grappa in Italy. This paper comprehensively reviews fundamental and applied aspects of the manufacture of these spirits, encompassing their composition as well as metabolic reactions and microbial ecology that determine such composition during fermentation. These spirits adhere to maxi mum levels of methanol (potential toxic compound) and 2-butanol (potential flavor defect) fixed by EC regulations. Available studies pertaining to bagaceira, orujo and grappa have indicated that the final quality of these spirits depends strongly on the quality of the fresh grapes, the storage condi tions, and the distillation equipment and procedure employed