Nitrogen modulation of yeast fitness and viability during sparkling wine production

• Nitrogen sources play a critical role in the acclimation of yeast strains.
• Yeast acclimation has a direct effect on second fermentation performance.
• Slow yeast growth correlates with higher viability during the second fermentation.
• Yeast strain plays a major role in the second fermentation development.

In the production of sparkling wine by the traditional method a second fermentation inside the bottle is required. To survive in such conditions of high ethanol concentration and high pressure, yeast cells must previously undergo an acclimation process. In this study, we investigated the role of the nitrogen composition during the acclimation phase by measuring growth and fermentative parameters through the second fermentation process. We used eight Saccharomyces cerevisiae strains of different origin to determine the impact of yeast genetic background on the efficiency of the acclimation process. The nitrogen source used in the acclimation media had a strong impact on yeast growth during this phase, but also affected significantly fermentation kinetics during the second fermentation. The yeast strain origin mostly affected the second fermentation kinetics. Surprisingly, the use of a medium rich in amino acids that are precursors of fusel alcohols, although triggered slow growth during the acclimation phase, it increased yeast viability and fitness through the second fermentation. Overall, we demonstrated how the nitrogen composition of the acclimation media impacts on yeast fitness and viability. The modification of the nitrogen composition during this phase is proposed as a tool to optimize yeast performance during the second fermentation.