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Aims: Grenache noir and Syrah are the predominant grape varieties in the French Rhone valley vineyard. This study aimed at identifying the odorants generated from glycoconjugates extracted from wines made with Grenache noir and Syrah. Methods and results: Synthetic model wines enriched with glycoconjugates, treated or not with enzymes, were stored at 45 °C for 3 weeks, or at 13 °C for 18 months. Aromas generated were extracted and analyzed by GC-Olfactometry (only samples from accelerated aging) and were further quantitatively determined by GC-MS. Analysis of the extracts allowed to identify 49 odorants, including 27 that could be aglycons, or related compounds, of glycoconjugates from the grapes. In addition, the active compounds were quantified in similar experiments led in conditions of natural aging for 18 months. Conclusion: The two varieties, Grenache noir and Syrah, were distinguishable by 14 odorant zones. Multivariate analyses (PCA) performed with the amounts of aroma compounds formed during both model and natural aging confirmed the effect of the glycosidase treatment on the acceleration of the aroma compounds formation and on the increase of the varietal differences of the wines. Significance and impact of study: GC-Olfactometry coupled with GCMS were good techniques to indentify and apreciate the odorants generated from glycoconjugates in the wines of Syrah and Grenache Noir, but in the context of a blend of odors, these techniques showed their limits and did not permit to determine the real impact of a molecule in the global aroma of the wine perceived by the taster. Other methods as additive techniques should be used to complete this study.

Aims: The aim of this study was to demonstrate the impact of the volatile compounds, arising from glycosidic precursors contained in the berries of Vitis vinifera L.cv Syrah and Grenache noir varieties, on wine aromas from these varieties. Methods and results: The sensory analysis was used to compare Grenache noir and Syrah wines. The role played by the glycosidic precursors on the future odorant profile of the wines from both varieties was demonstrated in an experiment by increasing their natural content in glycosides. Then, odorant compounds were generated by aging treatments, heating at 45 °C for 3 weeks, preceded or not by enzyme addition, or natural aging for 18 months. The wines were then submitted to a selected and trained panel. Samples were compared using triangular test. Furthermore, a quantitative descriptive analysis was carried out to determine the aroma attributes describing and discriminating the wines from the two varieties. Conclusion: The glycoconjugates increased the global aromatic complexity, and enhanced the fruity aromas in Grenache wines and the leather or olive aromas in Syrah wines. The use of glycosidase enzymes led to a stewed fruit character in Grenache wines, whereas in Syrah wines, the samples enriched with glycosides differed according to the « terroir ». Significance and impact of study: This study showed the impact of the glycosidic fraction of the grapes on the varietal aroma of wines. Furthermore, comparisons of the results obtained by both aging techniques highlight the experimental interest of the aging model but also its limits.