Vitamin preferences of non-Saccharomyces wine yeasts

by | May 21, 2024 | South Africa Wine Scan

In winemaking, the spotlight has recently shifted towards non-Saccharomyces yeasts, which have shown significant potential to enhance the complexity and quality of wines. While Saccharomyces cerevisiae has long been the dominant player in wine fermentation, researchers are now uncovering the unique contributions of non-Saccharomyces yeasts. Part of this research is understanding the vitamin consumption behaviours of these yeasts, which is crucial for optimising their use in winemaking.

In the article titled “To each their own: Delving into the vitaminic preferences of non-Saccharomyces wine yeasts,” scientists investigated the vitamin preferences of three commercially available non-Saccharomyces wine yeasts: Starmerella bacillaris, Metschnikowia pulcherrima, and Torulaspora delbrueckii. These yeasts were studied in wine-like conditions to mimic the natural environment of grape must during fermentation.

 

The role of vitamins in yeast metabolism

Vitamins play crucial roles in various biochemical processes and are essential for yeast metabolism. Deficiencies in these micronutrients can impair yeast growth and fermentation performance, leading to undesirable outcomes in winemaking, such as sluggish fermentations or the production of off-flavours.

In Saccharomyces cerevisiae, vitamins such as thiamine (B1), biotin (B7), and pantothenic acid (B5) are crucial for yeast metabolism, influencing growth rates and fermentation kinetics. Thiamine is necessary for carbohydrate metabolism and the synthesis of nucleic acids and lipids. Biotin plays a key role in fatty acid synthesis and amino acid metabolism. Pantothenic acid is vital for synthesising coenzyme A, a cofactor involved in numerous metabolic pathways.

Vitamins can also influence wine’s sensory attributes. For example, deficiencies in certain vitamins can lead to the accumulation of undesirable sulphur compounds, which can negatively impact wine’s aroma and taste. Ensuring adequate vitamin levels can help prevent these issues and contribute to a more favourable flavour profile.

Yeasts can also synthesise specific vitamins, release them in the medium and sometimes take them up again.

While the vitamin requirements of Saccharomyces cerevisiae are relatively well understood, the needs of non-Saccharomyces yeasts still need to be explored.

 

Distinct vitamin preferences

The study revealed that non-Saccharomyces yeasts exhibit species-specific preferences for different vitamers, the closely related forms of vitamins. For instance, the research highlighted how nicotinamide (a form of vitamin B3) is consumed differently by the three yeast species: it is assimilated by Torulaspora delbrueckii, left untouched by Starmerella bacillaris, and produced by Metschnikowia pulcherrima during their growth.

Moreover, the study found that all three non-Saccharomyces yeasts consumed all the vitamers of vitamin B1, indicating its essential role in their metabolism. This common requirement suggests that vitamin B1 should be closely monitored and supplemented, if necessary, during mixed fermentations to ensure optimal yeast performance.

 

Implications for mixed fermentations

Mixed fermentations, where non-Saccharomyces yeasts are inoculated before Saccharomyces cerevisiae, are gaining popularity because of the non-Saccharomyces yeasts’ ability to provide bioprotection (resulting in lower sulphur dioxide usage), aroma and flavour complexity and slightly lower alcohol concentrations. However, managing the nutritional needs of multiple yeast species in such fermentations can be challenging. This study’s findings provide valuable insights into the vitamin preferences of non-Saccharomyces yeasts, paving the way for more effective management of mixed fermentations. For example, if a particular non-Saccharomyces yeast requires high levels of a specific vitamin that is also highly consumed by the chosen Saccharomyces cerevisiae, winemakers can supplement the must with a yeast nutrient that contains that vitamin to avoid competition and ensure healthy yeast growth.

 

Future directions

While this study has shed light on the vitamin preferences of three specific non-Saccharomyces yeasts, it also opens the door to further research. Other strains of these species and other non-Saccharomyces species should be evaluated to determine if similar patterns exist. Additionally, investigating the interactions between different yeast species during co-fermentations can provide deeper insights into their nutritional dynamics and potential competitive behaviours.

 

Conclusion

By unravelling yeasts’ unique nutritional needs, scientists and winemakers can develop more targeted strategies for managing fermentations, especially multispecies spontaneous fermentations.

 

References

Evers, M.S., Ramousse, L., Morge, C., Sparrow, C., Gobert, A., Roullier-Gall, C., Alexandre, H. (2023). To each their own: Delving into the vitaminic preferences of non-Saccharomyces wine yeasts, Food Microbiology, Volume 115, 104332, https://doi.org/10.1016/j.fm.2023.104332.

 

Image: Needpix.com

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