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July 2015 P R A C T I C A L W I N E R Y & V I N E YA R D 59 W I N E M A K I N G On the other hand, these compounds can exhaust the action of other com- pounds, which act as masking agents for the fruity character, or they could be the precursors of transformation products such as furfyl thiols possessing strong coffee aroma and furfuryl ethyl ester pos- sessing kerosene-like aroma both being able to mask fruity flavors. 3,18,21,22 Overall oak aroma descriptor—The most potent contributors to overall oak aroma are compounds related to barrel toasting: vanillin, 5-hidroxymethylfurfrual and total furfural. The cis-methyl-octalac- tone is also among these contributors, but its content is less systematically higher in more intense oaky samples in comparison with the three above-mentioned chemicals. The role of furanic compounds in this interaction could be explained in the same way as for the fruity descriptor: enhancers of oaky flavor, markers and/ or precursors of potent odorants per- ceived as oak barrel-extracted aroma. The vanillin and cis-methyl-octalactone could be regarded as direct contributors and/or possible enhancers of this descriptor. Vanilla/pastry descriptor—The com- pounds involved are cis and trans- whisky-lactones, eugenol and vanillin, while furfural and 5-methylfurfrual con- tents were found to be systematically much lower for more intense vanilla sam- ples. The cis-whisky lactone was found to be the most important contributor to this descriptor, which is in accordance with previous studies. The role of furfural and 5-methylfur- frual seems to be the same for the fruity descriptor; they participate through dif- ferent mechanisms to mask vanilla/pastry flavor. 400 300 200 100 0 400 300 200 100 0 400 300 200 100 0 Chardonnay Sauvignon Blanc Semillon Variety cis-whiskey-lactone ★ 2 º 1 YES NONE Overoaked Figure 2. Distributions of over-oaked and non-over-oaked samples as function of amount of cis- whisky-lactone (μg/L) for each variety. The distribution is presented as boxplots (box-and-whisker plot) with the size of box representing 75% of total variance and the band inside corresponding to the median. The whiskers represent 90% of total variance, while rounds are outliners. 145 Jordan Street • San Rafael, CA 94901 • 415-457-3955 • Fax 457-0304 • www.boswellcompany.com