The role of malolactic bacteria metabolism on the organoleptic qualities of wines

Abstract

Lactic acid bacteria (LAB) are essential microorganisms in winemaking due to their role in malolactic fermentation (MLF) [1]. This process not only ensures the biological stabilization of wine through the decarboxylation of malic acid into lactic acid but also contributes to modifications in the chemical composition of the wine [2][3]. In fact, volatile and non-volatile compounds provided by LAB metabolism are important for the aromatic complexity of wines [2]. While the metabolic activity of LAB is known to influence key wine properties, the detailed metabolomic impact of different LAB strains in varying wine matrices remains poorly understood.

This study aimed to investigate metabolomic profiles resulting from the activity of nine LAB strains across four distinct wine matrices, using advanced metabolomic tools such as liquid chromatography-mass spectrometry (LC-MS) [4]. First the untargeted analysis focused on major families of compounds, including phenolic compounds, lipids, amino sugars, peptides, and carbohydrates. Then a targeted approach using KEGG libraries allowed to identify molecules of interest.

The results reveal different metabolic profiles, which can be attributed to the specific metabolic characteristics of the strains tested. Indeed, some of the tested LAB strains exhibited higher activity on phenolic compounds, potentially impacting wine stability and mouthfeel, while others were more associated with changes in lipids, carbohydrates or peptides fractions, which could influence downstream fermentation processes or the physicochemical properties of wine. The composition of the starting wine matrix was also found to play a critical role, as certain matrices favored the production or transformation of specific families of compounds within the same strain.

These findings provide new insights into the metabolic diversity of LAB and their interactions with the chemical environment of wine. Thus, the selection of specific LAB strains could be a powerful tool for tailoring the metabolic profile of wines, depending on the initial composition of the wine and the desired characteristics.

Further exploration could be undertaken into how LAB metabolism can be harnessed to achieve specific enological objectives and improve the aroma complexity of wines.

References

[1] Lerm, E., Engelbrecht, L., Du Toit, M., (2010). Malolactic fermentation: the ABC’s of MLF.

[2] Virdis, C., Sumby, K., Bartowsky, E., Jiranek, V., (2021). Lactic Acid Bacteria in Wine: Technological Advances and Evaluation of Their Functional Role. Front. Microbiol. 11.

[3] Mendes Ferreira, A., Mendes-Faia, A., (2020). The Role of Yeasts and Lactic Acid Bacteria on the Metabolism of Organic Acids during Winemaking. Foods 9, 1231.

[4] Honoré, A.H., Thorsen, M., Skov, T., (2013). Liquid chromatography–mass spectrometry for metabolic footprinting of co-cultures of lactic and propionic acid bacteria. Anal Bioanal Chem 405, 8151–8170.

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