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p r a c t i c a l w i n e r y & v i n e ya r d O c t O B e r 2 0 1 4 61 w i n e M A K i n G O ak barrels have long been used in fine winemaking — initially for easy handling of wine dur- ing production, storage and transport. Oak became accepted for its positive effects on wine development, namely to provide pleasant aromas and the stabilization of red wine color. During aging in oak barrels, wine composition changes because of the addition of phenolic compounds and other molecules extracted from the wood. Ellagitannins (hydrolysable tan- nins) are among these substances. In oak heartwood they may represent 10% of the dry weight and are responsible for the high durability of this wood. 11 The sensation imparted by ellagitan- nins was described as astringent at rela- tively low concentrations spanning from 0.2 to 6.3 µmol/L, whereas bitterness was strongly dependent on ellagitannin structure (a bitter taste was perceived at threshold concentrations between 410 and 1,650 µmol/L). 7 C. Chira et al. has observed that ellagitannin levels in a model wine solution are 45% of the total astringency variance. 3 Oak also contains a high level of vola- tile compounds that have a great impact on wood-matured wine aroma. The main volatile compounds susceptible to migra- tion from oak wood to wine are the cis and trans isomers of -methyl-- octalac- tone, furfural and its derived compounds, phenolic aldehydes such as vanillin and syringaldehyde, and volatile phenols such as eugenol, guaiacol and ethyl- and vinyl- phenols. Their extraction from oak barrels depends mainly on wine composition and the quantity of compounds that are potentially extractable during the contact time between wine and oak. At present, alternatives to the oak bar- rel are being evaluated to carry out the wine-aging process. This practice was approved and legislated by the European Community in 2006. (CE 2165/2005 and CE 1507/2006) Different shapes of oak wood pieces are used: chips, cubes or beans, powder, shav- ings or granulates, dominoes and blocks or segments. Factors such as amount of wood added and contact time between wood and wine affect both sensory and chemical wine characteristics — especially their wood-related volatile composition. 5 Until recently, it has not seemed very logical to establish an aging period in barrels or with wood pieces through leg- islation. Hence, it would be important to know more about influence of the wine composition in the process of the extrac- tion of oak compounds. A study of wine volatile and non- volatile composition along with a tasting assessment would be a more efficient method to establish the optimum contact time between wine and oak wood. The objectives of this study were to define the chemical (ellagitannins and volatile composition) and sensory char- acteristics of wine treated with wine- woods (staves) representing different toasting methods with the aim to moni- tor the kinetic levels of extraction of the above compounds for 12 months. The staves are samples (100 x 11 x 0.12 cm) from Quercus robur oak species from a forest in the center of France. After 24 months of natural seasoning in the Tonnellerie Nadalié seasoning park (Ludon-Medoc, France), they were sub- mitted to different toasting processes according to the desired final product using a revolving drum and oak fire (Table I). The toasting level impact on both vola- tile and non-volatile compounds and sensory perception were studied in parallel. The relationship between the chemical composition and the sensory assessment of oak also was investigated. Oak wood volatile composition The following wood volatile compounds were studied: furanic aldehydes, furfural and 5-methylfurfural, the two isomers of methyl--octalactone, cis and trans (com- monly known as oak lactones or whiskey lactones), the volatile phenols guaiacol, eugenol and isoeugenol; the aldehyde Three winewoods (staves) L to R: light toast, medium toast and Noisette. Photo by Tonnellerie Nadalie. Table I: Tas ng Characteris cs Oak toast Toas ng Temperature (oC) Toas ng Time (hours) LT (light toast) 165 2.0 MT (medium toast) 180 3.0 M+ (medium-plus toast) 190 3.5 Noise e 180 5.0 Special (medium toast with watering) 180 3.0 How extraction of oak volatiles and ellagitannin compounds affect sensory profile of wine aged with French winewoods iMPacT oF chEMicaL coMPoSiTioN oN RED wiNE quaLiTy Kleopatra Chira and Pierre-Louis Teissedre, University of Bordeaux, INRA, ISVV, Villenave d'Ornon, France BY