Impacts of non-Saccharomyces yeasts on nutrient composition and aroma profile of wines during co-fermentation with Saccharomyces cerevisiae and Levilactobacillus brevis

Non-Saccharomyces (NS) yeasts have recently garnered considerable attention due to their ability to improve wine malolactic fermentation (MLF) undertaken by lactic acid bacteria (LAB). However, the nutritional contribution of NS yeasts to LAB during mixed fermentation has not been fully elucidated yet. In this study, five NS yeast species (Torulaspora delbrueckii, Lachancea thermotolerans, Issatchenkia orientalis, Hanseniaspora opuntiae, and Pichia kluyveri) were used. Each NS yeast was co-inoculated with Saccharomyces cerevisiae and Levilactobacillus brevis responsible for alcoholic fermentation and MLF, respectively. The results showed a significant interaction regarding microbial growth. All five NS yeasts stimulated cell viability and MLF activity of L. brevis compared to the fermentation without NS yeasts. NS yeasts created favorable nutritional conditions for L. brevis by increasing the contents of mannose/mannoproteins (1.5-2.6 folds) and essential amino acids in wines without elevating the levels of potential inhibitors (ethanol and medium-chain fatty acids). The aroma profiles of resulting wines were distinguished by different concentrations of esters, fatty acids, and higher alcohols. Taken together, P. kluyveri and H. opuntiae showed potential as compatible candidates for improving both MLF and aroma. Our work confirms the beneficial activity of NS yeasts in terms of supporting LAB during co-fermentation.