Ana Hranilovic,* Julia Capitanio, Chantal Mansour, Margaux Bernard, Maitena Muro, Philippe Marullo, and Joana Coulon
*Laffort, 11 Rue Aristide Berges, 33270, France (ana.hranilovic@laffort.com)

Trends continually evolve, and the wine sector is no exception. Consumers and winemakers alike are steering away from heavier wines in favor of lighter, fresher, and more aromatic profiles. This work focuses on selection and characterization of microbial strains suitable for achieving such profiles. Two novel Saccharomyces cerevisiae strains, Zymaflore Xarom and Klima, were developed using QTL-assisted breeding for enhanced aromatic intensity and lower ethanol yield, respectively. They were compared for their production of primary and secondary metabolites in a series of fermentation trials with variable temperature and grape juice composition. Unlike typical S. cerevisiae starters, both strains could either preserve or produce malic acid during alcoholic fermentation. The largest malic acid production (0.9 g/L) was observed in red wine fermented with Klima at lower fermentation temperature (21 versus 26°C) and increased sugar content (16 versus 15% vol. alc.). The pH/titratable acidity of wines were in line with the yeast-derived modulation of malic acid. In both strains, higher temperature and sugar content boosted glycerol production, irrespective of acetic acid formation. Moreover, the levels of volatile thiols systematically increased with higher white wine fermentation temperatures (21 versus 18°C). The two yeasts exhibited distinct ester profiles: Klima was associated with increased ethyl esters, which were more abundant at lower temperature. In comparison, Xarom favored production of acetate esters regardless of fermentation temperature. Sensory analysis validated specific metabolic fingerprints of each strain in different matrices, with temperature-derived modulation of fruity and fermentative notes. This study therefore highlights the efficacy of readily implementable solutions, such as yeast strains and fermentation temperature, to fine-tune freshness and differentiate wine styles.

Funding Support: Laffort