Fermentative performance of indigenous Lachancea thermotolerans in high-sugar and low-acid wine production: Insights from volatomics and metabolomics.

The impact of climate change on grapevine cultivation has led to challenges in winemaking, particularly in terms of elevated sugar levels and reduced acidity in grapes. To address this, the specie of Lachancea thermotolerans (LT) with high lactic acid production potential have gained attention. This study explores the co-fermentation of the selected LT with Saccharomyces cerevisiae CECA to improve the chemical and flavor profiles of wine. Four different inoculation timings were tested in Cabernet Sauvignon fermentation to investigate the effects on metabolic pathways and fermentation performances. The results indicated that indigenous L. thermotolerans A38 slightly prolonged the fermentation time (13-14 days) but produced wine with lower volatile acidity compared to the pure inoculations of S. cerevisiae CECA (12 days). In contrast, co-fermentation with L. thermotolerans A38 led to the higher acidity and altered the metabolic profile of the wine, including increased lactic acid production (1.38-3.02 g/L), especially when S. cerevisiae was inoculated 48 h after LT fermentation (3.02 g/L). In co-fermented wines with LT strain, the levels of several aromatic volatiles, including phenylethyl alcohol (increasing by 4.10-37.64 %), phenylethyl acetate (by 6.72-302.19 %), ethyl lactate (by 4.48 folds), and ethyl acetate (by 2.65-83.07 %), were significantly increased, along with some terpenes. Metabolomics analysis revealed that different inoculation timings significantly influenced the microbial biosynthesis pathways of flavonoids and amino acids, thereby altering the production of aromatic compounds. This study provides new insights into the role of L. thermotolerans in winemaking and presents an effective strategy for addressing the acidity issues associated with climate change-induced grape composition changes.