Ana Hranilovic,* Marina Bely, Isabelle Masneuf-Pomarede, Joana Coulon, Warren Albertin, and Vladimir Jiranek
*Laffort, 11 Rue Aristide Berges, France (ana.hranilovic@laffort.com)

Insufficient acidity in grapes is commonly corrected by adding tartaric acid during winemaking. An alternative approach involves bio-acidification with Lachancea thermotolerans (LT) via lactic acid production during fermentation. Our work first described the genetic and phenotypic diversity of ~200 LT strains, then tested the performance of their subset conjunction with Saccharomyces cerevisiae (SC). An LT strain with exceptional bio-acidifying properties was selected (Zymaflore Omega) and further characterized across a range of conditions. The follow-up study aimed to compare the profiles of bio-acidified LT wines and acid-adjusted SC wines, and to evaluate the use of LT wines as blending components. High sugar/pH Merlot was fermented with a sequential culture of LT and SC, and an SC monoculture. The aliquots of the SC control (4.0) were acidified with either tartaric or lactic acid to the pH of LT wine (3.6). The initial LT and SC wines were also blended in three proportions (1:3, 1:1, 3:1). Chemical analysis revealed major differences in various wine parameters (e.g., ethanol content, acidity, color, volatile compounds, amino acids). The compositional modulations were reflected in wine sensory profiles, confirmed via rate-all-that-apply evaluation by 30 wine experts. Sensory profiles of the bio-acidified LT wine and the lactic acid-adjusted SC wine were similar, contrasting with the tartaric acid-adjusted SC wine. Lactic acid-adjusted SC wine had enhanced red fruit flavor, with less hotness, bitterness, and body than the tartaric acid-adjusted wine. This was driven by differences in acidity perception, affected by titratable acidity (rather than pH) of wines. An inhibition of Brettanomyces bruxellensis was also observed in the bio-acidified LT wine and the lactic-acid adjusted SC wine. The profiles of blends were modulated depending on the proportion of the bio-acidified wine, highlighting the potential of this approach to adjust wine acidity and style.

Funding Support: Laffort