Biochemistry & Physiology: Open Access
Open Access

The chemical composition of the grape, especially in organic acids, has an impact on the final wine’s quality and flavour. While certain acids are produced during wine fermentation, it is during this biological phase that winemakers must intervene in order to produce a wine with the proper acidic balance. When present above his detection threshold, acetic acid, which is produced during yeast metabolism (fermentation) and also, among other things, during the metabolism of acetic and lactic acids, has a negative effect on yeast fermentation production and affects wine quality. Biological deacidification by yeast and bacteria is considered the most natural strategy for lowering high acidity in dry wines. Since lactic acid bacteria (LAB) may absorb malic acid and convert it to lactic acid, malolactic fermentation (MLF) is the most popular form of biological deacidification or demalication. In contrast to malic acid, it is smoother in the teeth. Malic acid can also be degraded by non-Saccharomyces yeasts including Schizosaccharomyces pombe and Lachancea thermotolerans. The first converts it to ethanol through malo-ethanolicdeacidification , while L. thermotolerans produces lactic acid, allowing the wine to reach its maximum acidity and flavour potential. All bio-demalication methods stop using LAB strains, resulting in fruitier wines with lower levels of acetic acid and biogenic amines. Non-Saccharomyces yeasts, on the other side, have a limited alcohol threshold, so it’s better to use them in conjunction with Saccharomyces cerevisiae strains to end wine fermentation [1-3].

Conclusion

Malolactic fermentation by Lactic Acid Bacteria strains has become the standard method of biological demalication used by winemakers. Subproducts such as acetic acid and biogenic amines, on the other hand, may be produced during malolactic fermentation, imprinting the wines with undesirable and even harmful characteristics. One of the promising enological steps in enhancing wine quality is the use of wine yeast strains in the demalication process. Biological deacetification is the same way. The efficiency of the deacetification process is dictated by the yeast strains used, which contributes to higher-quality wine. Studying the pathways involved in yeast carboxylic acids transporters, and how they act in response to environmental changes such as carbon source supply, is one step toward enhancing biological demalication deacetification extracellular pH and acid stress conditions.

References

1. Vilela-Moura A, Schuller D, Mendes-Faia A, Silva RF, Chaves SR, et al. (2011) The impact of acetate metabolism on yeast fermentative performance and wine quality: Reduction of volatile acidity of grape-musts and wines – Mini review. Appl Microbiol Biotechnol 89: 271-280.
2. Inês A, Tenreiro T, Tenreiro R, Mendes-Faia A (2008) Review: The lactic acid bacteria of wine- Part I: Science Téc. Vitiv v.23: 81-96
3. Van Rooyen TJ, Tracel RP (1987) Biological Deacidification of musts induced by yeasts or malolactic bacteria and the effect on wine quality. S Afr J Enol Vitic 8: 60-69.