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April 2017 WINES&VINES 45 natural wood compounds charac- terized by a strong, sweet taste. These compounds could be con- sidered an important contributor to the taste balance of barrel- aged wines. The analysis of sweet (QTTs) and bitter (Glu-BA) triterpenoids in oak wood provide new insights into the chemical composition of oak wood and interpretation of its organoleptic effect on wine and spirits. This study showed that sessile oak was rich in sweet QTTs and poor in bitter Glu-BA, while pedunculate oak samples exhib- ited high levels of Glu-BA and low levels of QTTs. This distinction can be related to the preferential use of sessile oak for élevage. The practical importance of this finding consists in allowing for cooper and winemaker to adapt its wood selection for making barrels with a "sweet" oak profile—or, in contrast, to decrease the "sweet" component if needed. Analytical criterion of species differentiation Beyond this significant trend, the large inter-individual variations of concentrations observed for these compounds within each species was similar to previous observations concerning oak- lactone or ellagitannins. Indi- vidually, none of these compounds was sufficient to discriminate ses- sile and pedunculate oak wood. However, a Triterpenoids Index (TI) reflecting the triterpenoids profile of wood samples was cal- culated and showed a clear-cut differentiation between species without any equivocal sample or recovery between species. The measurement of this TI appeared consequently as a promising tool to identify oak species by a chem- ical method in addition to genetic assignment. U n t i l n o w, u n a m b i g u o u s chemical differentiation of oak species had only been achieved by use of non-targeted analysis with FT-ICR followed by statisti- cal treatment. 28 Such an ap- p r o a c h g i v e s a n a c c u r a t e fingerprint of the studied sam- ple, and its species assignment is based on the comparison of this fingerprint to a database collection of previously ana- lyzed samples. Moreover, as FT-ICR is a very powerful but highly costly tech- nique, its use is reserved for few laboratories specialized in mass spectrometry. This constitutes a limitation for the routine appli- cation of this technique by the cooperage industry. In contrast, the targeted method presented here involves the LC-MS quanti- fication of only four compounds with straightforward sample preparation and short analysis time. The species assignment can be obtained directly, without any statistical treatment or com- parison with a database. T h i s n e w, d i s c r i m i n a t i n g method was based on taste-active molecules, likely to modify the organoleptic properties of wine. It appears promising for various applications, in particular for a better selection of oak used in cooperage, allowing a more har- monious marriage with wine. Axel Marchal, Ph.D., is a lecturer at l'Université de Bordeaux, ISVV, Unite de R e c h e rc h e Œ n o l o g i e i n V i l l e n a v e d'Ornon, France, where Pierre Waffo- Teguo is a professor. Andrei Prida is the research and development manager for Tonnellerie Seguin Moreau in Merpins (Cognac), France. Denis Dubourdieu was a professor at l'Université de Bordeaux, ISVV, Unite de Recherche Œnologie. The references for this article are available online at winesandvines.com Individually, none of these compounds was sufficient to discriminate sessile and pedunculate oak. However, an index reflecting the triterpenoids profile showed a clear-cut differentiation between species. PRACTICAL WINERY & VINEYARD BARRELS Contact: Martin McCarthy North American Sales Director Cell: (707) 303-0941 martin@sauryusa.com Office: 1285 S. Foothill Blvd - Cloverdale, CA 95425 Ph: (707) 224-2377 - Fax: (707) 224-2390 www.saury.com Since 1873 Tonnellerie Saury has been built on the traditions and expertise of its master coopers and is now one of France's most well-known cooperages. Benefiting from a 100% self- sufficient supply of French oak and a fully integrated manufacturing process, Tonnellerie Saury maintains complete control over the raw materials for its production. Each barrel and tank undergo rigorous quality control testing during every step of the production process.