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Toasting is a key step in the barrel-making process. It plays an important role in the breakdown of oak wood compounds and thus influences the chemical composition and organoleptic properties of wines and brandies. However, the effect of toasting on distilled spirit quality has not yet been extensively studied. The objective of this study was therefore to study the impact of toasting on cognac eaux-de-vie by characterising the eaux-de-vie sensorially after 12 months of ageing. Eight eaux-de-vie aged in barrels with 8 different toasts were studied. The 8 toasts represented 4 different temperatures (low, medium, medium plus and high) and two toasting lengths for each temperature (one so-called “normal” and the other “slow”). Sensory analysis was carried out on these eaux-de-vie through several tests. First, a sorting test showed the differences between the samples and then training was carried out on previously chosen descriptors in order to build a sensory profile and perform a ranking test. The study was realised for two alcohol levels: 60 % (v/v), which is the alcohol level of eaux-de-vie in barrels, and 40 % (v/v), which is the alcohol level of a commercial cognac. This approach demonstrated that barrel toasting generally leads to significant sensorial differences in eaux-de-vie during ageing. These differences are greater between a lightly and a highly toasted barrel. This study is a first step in the characterisation of cognac eaux-de-vie aged in barrels made with different toasts.

The phenolic, aromatic and sensory evolution of a red wine under different oak aging conditions was evaluated. Neither phenolic nor fruity aromatic contents and profiles were impacted by the aging container or the derived oak products used. Meanwhile, a different woody aroma content was observed depending on the exposed wood area to wine volume ratio. From a sensory point of view, higher smoky, vanilla and/or spicy flavours were identified for all oak-aged wines when compared to the control (stainless steel tank), but they were all perceived as being as fruity as the control.

During fermentation or ageing of wines, oak wood is commonly used in form of barrels, casks or derived oak products (chips, winewoods, tankstaves, among others). It is well known that aroma, structure, astringency, bitterness, aromatic persistence and colour may change as a result of wine‒wood contact. A full-scale experimentation was performed under different oak ageing conditions in order to evaluate colour, phenolic, aromatic and sensory differences among final red wines (9‒months ageing). Oenological parameters and wine colour were not impacted by ageing modality. At the end of ageing, no differences were found in total phenolic and tannin contents. Regardless of the ageing modality, total content and profile of fruity volatiles were globally maintained with regard to control (≥ 86 %). In contrast, the higher the surface of wine‒wood contact per unit of wine volume, the greater the extraction of woody aromas. Thus, barrels led to wines with the highest level of woody aromas (515‒864 µg/L), followed by cask modalities (430‒470 µg/L). From a sensory point of view, descriptors highlighting the woody character of wine (vanilla, spicy) were enhanced in all oak‒aged wines when compared to control. However, our results indicate that a masking effect of fruity aroma by oak wood did not occur, since all modalities were perceived as fruity as the control. Thus, each oak ageing modality may lead to wines with a different woody character, without no impact on fruity perception, allowing wineries to achieve the targeted aromatic profile, good structure and just the right balance between fruity and woody aromas.

Ellagitannins are the main extractible oak wood phenolic compounds. These compounds are responsible for high wood durability and they can contribute to wine and spirits organoleptic quality (colour, astringency and bitterness). Despite their importance, their presence and forms in distilled spirits are not well known. Thus, the aim of this study was to develop and validate a measurement methodology and to quantify Cognac oak wood ellagitannins.

White wine is increasingly aged in oak barrels to enhance its stability, aromatic complexity and organoleptic properties. Thus, this research aimed to highlight chemical and sensory differences in Sauvignon Blanc wines linked to barrel size. Oenological parameters, color, total phenolics and fruity aroma were not generally impacted by barrel size. Meanwhile, the smaller the barrel, the higher the extraction of oak woody volatiles. From an organoleptic point of view, Sauvignon Blanc varietal aromas and typicity seemed to be better preserved by 500 L barrels.

Aims: In order to investigate the effect of vine training system on grape phenolic composition, a divided canopy system (Lyre) and a vertical shoot positioned trellis with two different pruning systems (Royat and Guyot) were applied in a commercial vineyard of cv. Xinomavro (Vitis vinifera L.). The quality of the produced grapes was determined with respect to three analytical parameters: anthocyanin content, tannin composition and proanthocyanidin structure. Methods and results: Monomeric anthocyanins, flavan-3-ol monomers and oligomers, tannin mean degree of polymerization (mDP), galloylation percentage (%G), and extension and terminal subunit structure were determined in seeds and skins by HPLC and LC/MS. Total phenolics, anthocyanin content, tannin concentration and antioxidant activity were measured in whole berries. Grapes and wines of the Lyre system were characterized by increased concentration of total and individual anthocyanins and total phenols. Individual flavan-3-ol monomers and oligomers were highest in Royat grape skins and Guyot seeds. Concerning proanthocyanidin structure, Royat grapes had significantly higher mDP and lower %G in skin and seed polymeric tannin fractions, compared to the other two systems, possibly leading to a lower grape astringency potential. Conclusion: Training system may affect grape anthocyanin concentration, total flavan-3-ol content as well as skin and seed proanthocyanidin structure (mDP, %G, extension and terminal subunits). Significance and impact of the study: The results of the present study could be of high importance to both grape growers and winemakers. Xinomavro grapes are rather poor in anthocyanins while being characterized by dry and astringent tannins. By adopting Lyre as a training system, higher anthocyanin contents could be achieved in grapes, resulting in wines with more attractive colour when adopting a longer pre-fermentation skin contact process. On the contrary, grapes of the Royat system might be more appropriate to produce full-bodied wines with higher ageing potential, due to their more appropriate tannin structure, by using longer maceration periods.

The proanthocyandin composition of skins and seeds of Bordeaux Merlot (M) and Cabernet Sauvignon (CS) grapes was evaluated by HPLC-UV-fluorescence for four consecutive vintages (2006 to 2009). The results indicated a strong vintage effect on the tannin profile of each variety. However, and in spite of the vintage effect, some tannin characteristics such as mDP, %G and %P allow discrimination of both Bordeaux varieties. The same analyses were carried out for the 2009 vintage of five Mediterranean grape varieties (Syrah, Grenache, Mourvedre, Carignan and Counoise). The results demonstrated differences among these five varieties. Syrah appeared to exhibit the highest concentrations of flavanol monomers and dimmers, especially in skins. The comparison study between Bordeaux and Mediterranean grape varieties for the same vintage (2009) revealed that mDP and %G for seed extracts were parameters specific to each vineyard area.

Nowadays, the development of naturalness as a concept is illustrated in the oenological field by the development of wine produced with lower inputs, sometimes even without any addition of SO2 throughout the winemaking process, up to the bottling stage. Despite the increase in the offer of these wines, they remain poorly explored in the literature and require characterization. This study was developed to evaluate the color of Bordeaux red wines without SO2 addition using colorimetric and polymeric pigments analysis. From a batch of commercial Bordeaux red wines with and without SO2 addition, and experimental wines produced from homogenous grapes according to different winemaking processes, colorimetric analyses (CIELab and color intensity (CI)) revealed a large difference in wine color depending on the presence or absence of SO2. Indeed, wines without SO2 were significantly darker and presented with a deeper purplish color. According to these observations, polymeric pigments were quantified using UPLC-DAD/ESI QTof, and a higher concentration of polymeric pigments bound by the ethylidene bridge was observed in wines without SO2. This correlated with differences observed for CIELab and CI. Finally, a comparison with polymeric tannins bound by ethylidene bridge was made and revealed that no differences were observed between wines with and without added SO2. This underlines the affinity difference between tannins and anthocyanins to react with acetaldehyde to form ethylidene bridges.

It is well established that C-glucosidic ellagitannins contribute to wine quality, and new forms of ellagitannins have been found recently in cognac eaux-de-vie. The contribution of some ellagitannin-derived spirit compounds to eaux-de-vie taste has been demonstrated recently. However, there is a gap in our knowledge of the content, composition, and evolution of C-glucosidic ellagitannins in this matrix. Indeed, the quantification of these compounds and their evolutionary compounds have never before been researched in cognac eaux-de-vie. Thus, the aim of this study was not only to quantify these compounds, but also to study their kinetics and to observe how they are impacted by barrel toasting. For this purpose, barrels representing eight different toasting levels were used to age the same eau-de-vie during the first 18 months. Ellagitannin quantification was carried out by HPLC-Triple quadrupole. The results showed that the evolutionary trend of the eight ellagitannins is the same for all eight types of barrel toasting. The maximum concentrations of C-glucosidic ellagitannins were found after 3 months of aging (up to 23 mg/L) before decreasing to 18 months (9.7 mg/L), whereas ellagitannin-derived spirit compound concentrations increased throughout aging (up to 130.9 mg/L). In addition, barrel toasting had such an impact on ellagitannin content that barrels could be differentiated according to their levels. Eaux-de-vie in barrels with high toasting were lower in ellagitannins concentrations.

During barrel production, the oak undergoes several processing stages that contribute to wine and brandy flavours. The toasting step is considered to have the most important influence on oak wood chemical composition as it causes the thermodegradation of some oak wood components. However, the effect of toasting on distilled spirit quality has not been thoroughly studied. Thus, the objective of this study was to determine the impact of barrel toasting on the cognac eau-de-vie sensory profile.

Cork taint, generally recognized by a musty or moldy off-flavor, is a serious problem facing the industry today when putting wines on the market. To assess the effectiveness of a food-grade plastic film in removing the compounds concerned, trials were carried out under real conditions. It was found that enological parameters as well as color are maintained, and there is no absorption of phenolic compounds or oak aromas. The plastic film improves the organoleptic quality of wines contaminated with haloanisoles, by reducing the concentration of compounds that give the cork taint and mask oaky and/or fruity aromas.

In the courses of studies on ellagitannin changes during oak wood toasting, two C-glycosidic ellagitannins were isolated from the french oak wood for the first time. These two compounds exhibited [M−H]− ion peak at m/z 1055.0631 (compound A) and at m/z 1011.0756 (compound B). A compound is named Castacrenin E and is produced by Castacrenin D oxidation. Castacrenin D is a vescalagin with an additional aromating ring to the C-1 through a C-C bond. These compounds are not only found under laboratory conditions but also in commercial oak wood representing different toasting methods and sizes. Their levels are conditioned by oak wood dimensions and toasting degree. The wood pieces with the smallest size present almost two times more compounds A and B. Moreover, the compound B is the only compound to be present in medium toasting temperatures of the smallest wood pieces. Both of them can influence either astringency sensation or bitterness taste.

The effect of the time of wood chip addition on phenolic content, color parameters and volatile composition of a red wine made by a native Greek variety (Agiorgitiko) was evaluated. For this purpose, chips from American, French, Slavonia oak and Acacia were added in the wine during and after fermentation. Various chemical parameters of wines were studied after one, two and three months of contact with chips. The results showed that the addition of oak chips during alcoholic fermentation did not favor ellagitannin extraction and the reactions involved in tannin condensation and anthocyanin stabilization. Moreover, wines fermented with wood chips contained higher contents of whiskey lactones, eugenol, ethyl vanillate and acetate esters while their ethyl ester content was lower compared with the wines where chip addition took place after fermentation. Practical Application: The outcomes of this study would be of practical interest to winemakers since they could improve the control over the wood extraction process. When chips are added after fermentation wines seem to have a greater ageing potential compared to the wines fermented with chips due to their higher ellagitannin content and enhanced condensation reactions. On the other hand, color stabilization and tannin polymerization occur faster when chips are added during fermentation resulting in shorter ageing periods suitable for early consumed wines.