Evaluation of bio-acidifying yeast Lachancea thermotolerans as a strategy to reduce the effects of climate change in Tempranillo grape must vinification

The effects of climate change are posing major challenges for winemaking, especially in warm regions. Rising temperatures are leading to a considerable increase in sugar content and a reduction in the acidity of grape juices. This has prompted the search for new chemical and biological tools to reduce these effects in winemaking. Lachancea thermotolerans represent an interesting tool for wine improvement, due to their effects on lactic acid, ethanol, and volatile acidity. In this study, we evaluated the sequential inoculation of Lachancea thermotolerans (AEB Italia) + Saccharomyces cerevisiae as an alternative to the addition of water and tartaric acid in the vinification of over-ripened wine must (Tempranillo cv.). To do so, we conducted a micro vinification experiment that included three experimental treatments (replicated four times); AAS = Addition of water + tartaric acid fermented with Saccharomyces cerevisiae, ALS = sequential fermentation with Lachancea thermotolerans followed by Saccharomyces cerevisiae and SAC = Only inoculation with Saccharomyces cerevisiae (control). We measured the lactic acid, malic acid, acetic acid, total acidity, pH, glucose + fructose, and ethanol concentration of the resulting wines. We found a higher lactic acid content and total acidity in ALS wines (2.2 g/L y 6.65 g/L) compared with AAS (0.13 g/L y 5.75 g/L) and SAC wines (0.18 g/L y 5.37 g/L). ALS wines showed a significantly lower pH (4.00) than SAC wines (4.19) but did not differ significantly from AAS wines (3.19). Finally, acetic acid was higher in ALS wines (0.89 g/L) than AAS wines (0.64 g/L) but did not differ significantly from SAC wines (1.02 g/L). Our results point out that the use of Lachancea thermotolerans in a sequential inoculation with Saccharomyces cerevisiae is an alternative to the addition of water and tartaric acid in the vinification of over-ripened Tempranillo musts.