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Hydric stress is a leading cause of atypical aging (ATA) in wine, characterized by unpleasant olfactory notes. The main sensorial and chemical marker of ATA is 2‐aminoacetophenone (AAP). Early detection of ATA before the second fermentation in sparkling wines (SWs) is crucial for producing high‐quality products. Climate change‐induced droughts significantly impact agriculture, including grape farming, particularly in vineyards with shallow soils and reduced available water capacity (AWC). This study examined the relationship between AWC and ATA in base wines (BWs) intended for SW production. Ten vineyards were classified into three AWC categories (low, medium, and high). Hydric stress levels were monitored over two growing seasons to explore their effects on vegeto‐productive behavior and AAP development. During the first vintage, drought conditions led to potentially ATA‐tainted BWs across all AWC classes. The impact varied with AWC, with low‐AWC vineyards experiencing higher stress and producing BWs with elevated AAP levels and vegeto‐productive imbalance. In contrast, the following season had unusual rainfall, resulting in some potentially ATA‐affected BWs, but no significant differences in AAP content or vegeto‐productive balance among the AWC classes were observed. In conclusion, grapevines on low‐AWC soils are at a higher risk of producing faulty BWs, particularly in dry vintages. [ABSTRACT FROM AUTHOR]

Highlights • A novel method for the analysis of mousy off-flavour compound in wine was developed. • Only filtration and basification were required prior to HPLC-MS/MS analysis. • The method was simple and rapid as well as highly reliable and robust. • LOQ was 0.23 μg L−1 for both red and white wine. Abstract 2-Acetyltetrahydropyridine (ACTPY), tautomers of 2-acetyl-1,4,5,6-tetrahydropyridine and 2-acetyl-3,4,5,6-tetrahydropyridine, is reported as one of the major compounds responsible for mousy off-flavour wine. A simple and rapid method for the quantitation of ACTPY in wine using HPLC-APCI-MS/MS was developed. Only filtration and basification were required for sample preparation prior to analysis. The analytical run time was approximately 17 min for one sample. Precision and accuracy tests confirmed that the method was highly reliable and robust. Limits of quantitation (LOQ) for red and white wines were estimated to be 0.23 μg L−1, which was sufficiently sensitive to allow the quantitation of ACTPY at its odour threshold level in water. The method can be implemented for routine objective screening of wines for mousy off-flavour, to determine sensory threshold levels in wine and to aid further research aiming to reduce the occurrence of this fault in wine. [ABSTRACT FROM AUTHOR]

Copper-sulfhydryl complexes in wine can be disrupted by addition of brine to release free hydrogen sulfide (H 2 S), and the resulting "brine-releasable H 2 S" is reported to correlate with formation of H 2 S during bottle storage. However, both the mechanism of the brine-release assay and factors affecting the stability of copper sulfhydryls under brine-release conditions are not well understood. By varying brine composition and concentration, it is shown that release of copper-complexed H 2 S requires the presence of a halide (Cl - and Br - ) and is not due to a general "salting-out" effect. Release of copper-complexed H 2 S by the brine dilution assay is highly temperature-dependent. When H 2 S and Cu(II) are added to a model wine, brine-releasable H 2 S decreases markedly (∼10-fold) after a 20 min incubation period prior to performing the brine-release assay. In commercial wines, the fraction of added H 2 S recovered through the brine-release assay was correlated with the initial glutathione (GSH) concentration ( r 2 = 0.58) but not with initial Cu. Negligible additional release of H 2 S from organopolysulfanes was observed following addition of a disulfide-reducing agent (tris(2-carboxyethyl)phosphine). As previous studies have reported a correlation between H 2 S formed under brine-release conditions and normal storage, these results suggest that the susceptibility of a wine to form latent copper-sulfhydryl precursors of H 2 S following copper addition is dependent on the concentration of sulfhydryls like GSH.

The level of hydrogen sulfide (H 2 S) can increase during abiotic storage of wines, and potential latent sources of H 2 S are still under investigation. We demonstrate that elemental sulfur (S 0 ) residues on grapes not only can produce H 2 S during fermentation but also can form precursors capable of generating additional H 2 S after bottle storage for 3 months. H 2 S could be released from S 0 -derived precursors by addition of a reducing agent (TCEP), but not by addition of strong brine to induce release of H 2 S from metal sulfide complexes. The size of the TCEP-releasable pool varied among yeast strains. Using the TCEP assay, multiple polar S 0 -derived precursors were detected following normal-phase preparative chromatography. Using reversed-phase liquid chromatography and high-resolution mass spectrometry, we detected an increase in the levels of diglutathione trisulfane (GSSSG) and glutathione disulfide (GSSG) in S 0 -fermented red wine and an increase in the levels of glutathione S-sulfonate (GSSO 3 - ) and tetrathionate (S 4 O 6 2- ) in S 0 -fermented white wine as compared to controls. GSSSG, but not S 4 O 6 2- , was shown to evolve H 2 S in the presence of TCEP. Pathways for the formation of GSSSG, GSSG, GSSO 3 - , and S 4 O 6 2- from S 0 are proposed.