Color Characterization of Bordeaux Red Wines Produced without Added Sulfites.

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.

Highlighting the varietal origin of eugenol in Armagnac wine spirits from Baco blanc, a hybrid grape variety.

We report on the first evidence of a varietal origin of eugenol as a molecular marker in Baco blanc, one of the grape varieties used to produce Armagnac. Eugenol was identified and quantified by HS-SPME-GC-MS. For two separate vintages, the concentrations found in monovarietal wine spirits made from Baco blanc, were, on average, 10 times higher than those in other Vitis varieties, ranging from 31.0 to 174.7 µg/L. Investigations were carried out to quantify eugenol in the wines used for distillation, in the musts and finally in several parts of the plant. For all matrices over both vintages, it was confirmed that eugenol is much more abundant in Baco blanc than in Ugni blanc and Folle blanche. Moreover, enzymatic hydrolysis made it possible to release a significant quantity of eugenol from precursors, demonstrating that more than 90% of eugenol is bound in the must and in the grape berry pulp.

Sensory Specificities Involving Acetaldehyde and Diacetyl in Wines Produced without Added Sulfur Dioxide.

Nowadays, the development of naturality concept is illustrated in the oenological field by the development of wine produced without the addition of SO2. Among its chemical properties, SO2 is able to react with carbonyl compounds to form carbonyl bisulfites. Acetaldehyde and diacetyl are the main carbonyl compounds of red wines, which could influence product perception. The goal of this paper was to evaluate their chemical and sensory impact in red wines produced without any addition of SO2. A first quantification approach revealed a lower concentration of these compounds in wines without added SO2 than in those produced with SO2. A sensory approach involving aromatic reconstitutions in wines in the presence or absence of SO2 revealed that analytical differences observed for acetaldehyde and diacetyl were able to impact wine freshness, with diacetyl being, moreover, involved in wine fruity aroma changes.

Methyl Salicylate, an Odor-Active Compound in Bordeaux Red Wines Produced without Sulfites Addition.

Red wines produced without the addition of any SO2 are currently the source of a new consumer trend. The first characterization approaches regarding these specific wines were devoted to sensory studies that highlighted differences according to the use of SO2 during winemaking. The goal of this paper is to extend our knowledge of such aromatic specificities. Examining experimental wines produced with and without the addition of SO2, aroma fractionation, gas chromatography coupled with olfactometry, and mass spectrometry were applied to identify compounds at the origin of the specificities of these wines. Thus, we identified methyl salicylate as being impacted by the use of SO2 during the winemaking process. Studying a large number of commercial Bordeaux red wines, methyl salicylate was significantly quantified at a higher content in wines without added SO2. A sensory approach revealed a significant impact of methyl salicylate on wines without the sulfite aroma, particularly concerning fruity aromas and wine freshness.