Role of Glycosidic Aroma Precursors on the odorant profiles of Grenache noir and Syrah Wines from the Rhone valley. Part 2: characterisation of derived compounds

Abstract

<p style="text-align: justify;"><strong>Aims</strong>: 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.</p><p style="text-align: justify;"><strong>Methods and results</strong>: 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.</p><p style="text-align: justify;"><strong>Conclusion</strong>: 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.</p><p style="text-align: justify;"><strong>Significance and impact of study</strong>: 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.</p>

Influence of different yeast/lactic acid bacteria combinations on the aromatic profile of red Bordeaux wine

“…Among these compounds, γ‐octalactone was the most representative, with levels ranging from 15.86 µg L −1 (XR/B28 wine) to 22.50 µg L −1 (522D/B28 wine), but it is unlikely to have had any aromatic impact in view of its perception threshold (35 µg L −1 ) . Little information is available concerning lactone formation pathways in wine, but they are assumed to be mainly synthesized from hydroxylated fatty acids or esters via an enzymatic or chemical pathway . The results of this study were consistent with previous observations that yeasts were capable of enzymatic esterification but not, apparently, LAB .…”

A GC-MS Based Analytical Method for Detection of Smoke Taint Associated Phenols in Smoke Affected Wines

“…These values were close to the lowest concentration level of 271 the working range. It was verified that these analytes presented rates of recovery and 272 levels of detection compatible with their thresholds of perception and the 273 concentrations expected in non-smoked fruit and wine [32] (Table 3). In summary,method developed here provides an acceptable level of accuracy for the determination 276 of volatile phenols which may contribute to smoke taint in wines prepared from 277 smoke affected fruit.…”

Influence of Maturity and Vineyard Location on Free and Bound Aroma Compounds of Grapes from the País Cultivar

“…Nonvolatile compounds are mainly present as glycoconjugates formed by an aglycone (volatile compound) and sugar moiety (Winterhalter & Skouroumounis, 2006). Compounds responsible for the varietal aromas that come from the grape are of special interest and may appear in the free and bound form, or as non-volatile flavour precursors (Sefton et al, 1996;Segurel et al, 2009). properties. This is the case of the Vitis vinifera cv.…”