Lachancea thermotolerans as a tool to improve pH in red wines from warm regions

In warm regions, a typical problem is to reach high pH in must together with excessive sugar concentration, this problem is being increased by climatic change. In most of the wine regions of the south centre of Spain, it is easy to find red musts with pH values in the range 3.8-4.0 that after fermentation frequently exceed pH 4. This low acidity is accompanied by alcoholic degrees that are often higher than 14% vol. By yeast selection, we have obtained one strain of Lachancea (formerly Kluyveromyces) thermotolerans that reduces pH value approximately in 0.5units making unnecessary the use of chemical acidification. The production of lactic acid by this strain is done using sugars as precursors, thus affecting the final alcoholic degree. Some collateral reduction of ethanol can be achieved, up to 0.5% v/v. The efficiency of this strain is higher than that of others commercially available today. The use of L. thermotolerans sequentially with Saccharomyces cerevisiae is a powerful tool to modulate acidity and ethanol in warm areas. In this work, the effectivity to reduce pH of a specific strain of L. thermotolerans has been verified in low and high pH musts in lab trials but also in semi-industrial fermentations with crushed grapes.