Innovative Fermentation Approach Employing Lachancea thermotolerans for the Selective Production of High-Acidity Wines, Designed for Blending with Low-Acidity Counterparts to Achieve Chemically and Organoleptically Balanced Final Compositions

The most notable effects of climate change on wine production are higher alcohol levels, lower acidity and changes to the regions suitable for growing grapes. One solution to acidity problems is the use of Lachancea thermotolerans, a yeast that produces lactic acid during fermentation, albeit at the cost of reduced aromatic complexity. A novel approach to addressing this problem is to use L. thermotolerans to produce wines with a very high acidity, regardless of other parameters, for subsequent blending with a control wine with a naturally low acidity. This achieves a balanced acidity while retaining the organoleptic characteristics of the control wine. This is a novel idea, as L. thermotolerans is not usually used in the final wine. However, the objective from the beginning is to create a blend that combines the best characteristics of the control wine with the improved acidity provided by L. thermotolerans. Base wines were produced by inoculating Saccharomyces cerevisiae 20, 40, or 60 h after inoculating L. thermotolerans. Base wines generally show an increase in lactic acid content and a decrease in certain key aromatic compounds, such as isoamyl acetate, 2-phenylethyl acetate, ethyl hexanoate, and ethyl octanoate. Concentrations of other compounds such as acetaldehyde and higher alcohols also increase. The base wines were then blended with a low-acidity control wine. The resulting blends exhibited higher acidity than the control wine, as well as better aromatic profiles, particularly regarding fruity and green fruit aromatic compounds, compared to base wines. Ten volatile compounds have been correlated with lactic acid production by L. thermotolerans, namely ethyl hexanoate; ethyl butanoate; 2-methylbutanol; ethyl heptanoate; isoamyl acetate; acetaldehyde; isobutanol; 2-phenylethanol; dodecanol; and acetoin. The first five are negatively correlated and the rest are positively correlated. Lastly, sensory analysis revealed that the blends achieved the best balance between acidity and aroma, making them the most popular with tasters.