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60 P R A C T I C A L W I N E R Y & V I N E YA R D July 2015 W I N E M A K I N G Toasty/smokydescriptor—The com- pounds involved are maltol and 5-hydroxy- methylfurfural. The thesis of indirect impact (enhancer, marker and precursor) seems to be more plausible here as well, because maltol is a compound with a high percep- tion threshold. Surprisingly we did not find any vol- atile phenols (guaiacol, 4-methyl-guai- acol, etc.) perceived in pure state as smoky. Their weak contribution could be explained by the low variation of parameters in comparison with percep- tion thresholds in wine. Spicy descriptor—The impact of wood compounds on this descriptor is rather difficult to explain, but we did not find here any impact of eugenol, described in its pure state as spicy/clove. Olfactory persistence descriptor— The samples described as having higher olfactory persistence were richer than their paired samples in trans, cis-whisky lactone, maltol, eugenol and vanillin. This group of compounds is char- acterized in general by low perception thresholds and a pleasant aroma. In addi- tion, most of them are relatively high- boiling: vanillin, whisky-lactones and maltol, which explain their retro-nasal persistency. Matrix effect study Wines made from Chardonnay, Sauvi- gnon Blanc and Semillon varieties were fermented and aged in new barrels pro- duced by Tonnellerie Seguin Moreau for six to 12 months. Sensory analysis The sensory analyses were performed by a tasting panel of 10 to 14 persons composed of professional enologists from internal staff of Seguin Moreau Cooperage and invited winemakers involved in wine pro- duction. The question asked was whether the coconut character extracted from oak decreased the value of wine, with the pos- sibility of answering yes/none. The chi-2 test was run according to which wine was attributed as YES (value decreased), NONE (value not decreased) and non-significant (p>0.05). The only wines receiving the unanimity of the panel (YES or NONE clearly attributed) were used in the following study. The Independent T-test was run for all the values of whisky-lactones (trans and cis) for the YES and NONE groups for each variety. The test was non-significant for trans-WL for all three varieties and very significant for cis-isomers. The box- plots are presented in Figure 2 for cis- whisky-lactone for all three varieties. The data presented stresses the dif- ference of whisky-lactone perception for different varieties. One can see that Sauvignon Blanc and Semillon are per- ceived as denatured by cis-whisky-lac- tone starting from 150 µg/L, while this boundary is much higher for Chardonnay (more than 200 µg/L). This observation corroborates the empirical knowledge that Chardonnay easily integrates oak flavors, while Sauvignon Blanc is very sensitive to over-oaking. Conclusions and prospective The compilation of knowledge about wood compounds' impact (evolution in wine medium and interactions) allows the prediction of the sensory perception of oak in wine and wine quality. The model developed by Seguin Moreau based on the aforementioned studies enable us to produce barrels with an improved consistency that better matches winemakers' expectations. PWV Bibliography 1. Atanasova, B., T. Thomas-Danguin, C. Chabanet, D. Langlois, S. Nicklaus, P. Etievant. 2005 "Perceptual Interactions in Odour Mixtures: Odour Quality in Binary Mixtures of Woody and Fruity Wine Odorants." Chem. Senses 30: 209–217. Master the art of winemaking Learn the scientific framework for successful winemaking with UC Davis Extension's internationally renowned online winemaking certificate program. The program is designed to provide you with: • Unparalleled learning from world-class instructors • Academic theory and real-world, commercial application • Critical networking opportunities • Convenient and flexible online learning Visit our website and start pursuing your passion today. extension.ucdavis.edu/winemakingcert ERROIR See what our students have accomplished.