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46 WINES&VINES February 2017 WINEMAKING PRACTICAL WINERY & VINEYARD research. 7,11,15,22 By contrast, the absence of a significant "grain" effect was more surpris- ing, and to understand this, it was necessary to examine the TP distribution in each type of grain. In "Distribution of Tannin Potential by Grain Size" (above), 14% of the fine- grain oak usually associated with LTP was actually HTP, while 17% of the medium- grain oak (usually associated with HTP) was LTP. Thus, under our research conditions, "atypical" wood (fine-grain with high tannin levels and medium-grain with low tannin levels) negated the differences between the two grain widths. Impact of geographic origin, grain and tannin levels on sensory profile Sensory analysis of the 2014 vintage trial wines clearly discriminated among the sam- ples on the basis of aromatic criteria. Inde- pendent of the geographic origin and grain, wines aged in HTP barrels exhibited signifi- cantly more intense empyreumatic notes related to toasted register (toast, caramel, coffee and chocolate), nuances and corre- spondingly less marked fruity aromas. However, aging in LTP barrels gave a more intensely fruity aromatic character with more discreet empyreumatic notes. (See "Sensory Analysis: Intensity of Empyreu- matic and Fruity Notes" on page 47.) In other words, the sensory profiles of wine aged in oak from the same forest with the same grain differed significantly, depending on the tan- nin level of the oak. For example, this was the case of the Tr-HTP-f protocol, which had one of the most markedly empyreumatic characters compared to Tr-LTP-f, which was radically different with more intense fruity aromas. These differences in fruity per- ception between the two TP levels were due to their chemical composition. The higher furanic aldehyde content of wines aged in HTP barrels diminished their fruity characters, 23 whereas the whisky lactones enhanced the fruity impression to varying extents, depending on the balance between the concentrations of these compounds and the molecules responsible for fruity aromas in the wine itself. 24,25,26 In agreement with the chemical analysis results, the tannin level of the oak was appar- ently a more discriminating factor for sensory qualities than simply geographic origin or grain. Among the other criteria assessed during the sensory analysis, only the overall assess- ment of the wines identified marked differ- ences between the different series of barrels. However, these differences were not statisti- cally significant. It is, nevertheless, interesting to note that the panel tended to prefer wines with less obvious empyreumatic character such as Be-LTP-f and Lo-LTP-m. Wood selection by tannin potential has the strongest impact on wine sensory profile The objective of this research was to assess the impact of geographic origin, grain and tannin levels of oak wood used in cooperage on the sensory profile of red wines. The results indicated that for barrels with the same geographic origin and grain width, a considerable variation of major oak aro- matic compounds was attributable to the tannin potential of the wood. This new analytical method of oak selection and classification offers the possibility of better exploiting the natural variability of oak and thus assuring precision and repeatability. This napa barrel repair shop Master Cooper - barrel repair - opening and closing of barrels for fermentation - barrel demos - tank repair making barrels work 918 Enterprise Way Unit K Napa, CA 94558 DISTRIBUTION OF TANNIN POTENTIAL BY GRAIN SIZE Low TP Medium TP High TP Fine grain 69% 17% 14% Medium grain 17% 33% 50% TP stands for tannin potential.