The fermentation vessel significantly impacts the flavor characteristics of white wine. This study provides a comprehensive flavor analysis of Sauvignon Blanc wines fermented in oak barrels and stainless-steel tanks. Wines fermented in new barrels exhibited higher levels of malic and tartaric acids compared with those fermented in old barrels or steel tanks, resulting in a more sour taste. Fermentation in oak barrels increased the content of majority phenolic compounds in wine compared to fermentation in steel tanks. GC–MS analysis revealed that the primary differential compounds present in the wines from various oak barrels and steel tanks included ethyl acetate, ethyl lactate, furfural, ethyl octanoate, isoamyl alcohol, isobutyl alcohol, 1-propanol, and acetic acid. Moreover, GC-IMS identified furan, pyrazine, acetaldehyde, and valeraldehyde in wines from oak barrels, which enhanced aromatic complexity. This study provides essential insights to promote the quality and distinctiveness of Sauvignon Blanc wines.

There is significant interest in the wine industry to develop methods to reduce the ethanol content of wine. Here the global transcription machinery engineering (gTME) technology was used to engineer a yeast strain with decreased ethanol yield, based on the mutation of theSPT15gene. We created a strain ofSaccharomyces cerevisiae(YS59-409), which possessed ethanol yield reduced by 34.9%; this was accompanied by the increase in CO₂, biomass, and glycerol formation. Five mutation sites were identified in the mutatedSPT15gene of YS59-409. RNA-Seq and metabolome analysis of YS59-409 were conducted compared with control strain, suggesting that ribosome biogenesis, nucleotide metabolism, glycolysis flux, Crabtree effect, NAD⁺/NADH homeostasis and energy metabolism might be regulated by the mutagenesis ofSPT15gene. Furthermore, two genes related to energy metabolism,RGI1andRGI2, were found to be associated with the weakened ethanol production capacity, although the precise mechanisms involved need to be further elucidated. This study highlighted the importance of applying gTME technology when attempting to reduce ethanol production by yeast, possibly reprogramming yeast’s metabolism at the global level.

Co-inoculation with Saccharomyces cerevisiae and non-Saccharomyces yeasts is an effective method to improve the flavor of cider. Wickerhamomyces anomalus, known for its high ester production capacity, was evaluated in combination with S. cerevisiae to identify optimal mixed yeast inoculants for improved sensory characteristics. Three W. anomalus strains and three inoculation ratio attributes (1:5, 1:1, and 5:1) were tested to assess their impact on the physicochemical indices and sensory attributes of cider. All the strains used as starters developed fermentation-producing ciders with alcoholic degrees between 6.22 and 6.36 (% v/v). Co-inoculation with W. anomalus resulted in significantly higher ester, volatile acid, and higher alcohol levels compared to those of S. cerevisiae monocultures, increasing the complexity of fruity and floral aromas. Furthermore, the proportion of W. anomalus strains in the inoculations was positively correlated with increased aromatic esters and higher alcohols. The Sc–Wa (1:5) cider showed the highest contents of ethyl ethanoate and 3-methylbutan-1-ol, contributing to a nail polish-like aroma. Sc–Wa (1:1) yielded a higher aromatic diversity than did Sc–Wa (5:1), suggesting that co-inoculation with a ratio of 1:1 may provide an effective fermentation strategy for cider aroma enhancement. These findings offer valuable insights into how non-Saccharomyces yeasts can be effectively applied in cider co-fermentation, providing a foundation for their future use in industrial applications.