Nitrogen levels decide which yeasts win in wine fermentation

Scientists have found that the amount of available nitrogen in grape must plays a crucial role in deciding whether commercial or indigenous Saccharomyces cerevisiae yeasts take control during fermentation. The findings suggest nitrogen management influences more than fermentation speed, potentially shaping a wine's aroma, flavour and regional character.

The study compared commercial starter cultures with indigenous yeasts isolated from spontaneous fermentations using synthetic grape must containing different levels of assimilable nitrogen. Commercial strains consistently outperformed native yeasts in nitrogen-rich conditions, while indigenous strains remained competitive or coexisted when nitrogen was limited.

Researchers also discovered that yeast strains differ in how quickly they absorb nitrogen and which amino acids they prefer. These differences help explain why nutrient levels alter the balance between strains. Although the work was carried out in synthetic must rather than commercial wineries, the findings could help winemakers fine-tune nitrogen additions to balance reliable fermentations with preserving distinctive local wine character.