A few concepts you may not know about yeast nutrition

Yeasts, like any living organism, carry in their DNA a set of innate responses that drive specific processes to meet their needs—both as individual cells and as a population.

The mission of yeasts

Their first mission is to colonize the environment they inhabit. That is why yeast will deploy every available resource to reach the highest possible population and outcompete other species. Producing new cells is a highly demanding process in terms of energy and nutrient requirements.

How does this process work? Here’s the explanation:

During the first hours, yeast prioritizes ATP generation from hexoses via the respiratory pathway, as it is far more efficient than fermentation. Carbon sources in grape must are abundant, so supply is not the limiting factor.

Yeast nitrogen requirements

Regarding nitrogen needs, it has been demonstrated that yeast requires 150–200 mg/L of FAN (Free Amino Nitrogen) to reach adequate populations at Vmax. If grapes do not provide these initial levels, an early correction is required by adding organic or inorganic nitrogen compounds.
It is important to consider that yeast shows preferences for certain nitrogen sources. We know, for example, that ammonium is readily assimilated and that among amino acids, yeast prioritizes glutamate and glutamine. But that topic deserves its own dedicated discussion.

Once yeast needs are covered :

Once established in the medium, yeast shifts its priority toward species survival. S. cerevisiae has a complex sensor system that supports decision-making to ensure persistence as conditions change. After a few hours, it stops relying on respiration and switches to the fermentative pathway.

Fermentation onset

Because S. cerevisiae is more firmly established and other yeast genera are highly sensitive to ethanol, those competing yeasts eventually disappear. This fermentation start is irreversible, and ethanol production will not stop until all sugar is consumed or the yeast dies.
That is why it is so important—preventively, before the onset of anoxic conditions—that S. cerevisiae has sufficient selective or autotrophic reserves to remain viable until sugars are depleted. This is where the debate begins: different theories on when and how to feed yeast.

When should yeast be fed?

At LEV2050, everything we apply to our products and processes is based on scientific fundamentals, study, and experimentation. That’s why we understand yeasts well—what they need and when they need it.

Once fermentation has started, yeast rapidly consumes available FAN to build a high population. From that point on, supplying organic nitrogen sources becomes critical before yeast can no longer assimilate them. This limitation appears when oxygen is depleted and the first degrees of alcohol begin to develop.

Remember: amino acids enter the cell via symport transport coupled to H⁺ proton uptake. Eventually, as ethanol progressively weakens the membrane, proton influx becomes excessive. Yeast responds by closing controllable uptake pathways—also preventing amino acid absorption.

Supplying organic nitrogen sources

For these reasons, it is essential to provide organic sources before reaching that point—typically when density has dropped by 5–10 points. This organic nitrogen is stored in vacuoles as reserves that yeast will draw on as needed to renew protein structures.

Nitrogen needs at this stage are much lower than during multiplication: 10–15 mg/L can be sufficient. This brings us to another key factor: the amino acid composition of organic nitrogen.

Amino acid composition of organic nitrogen:

Yeast faces an increasingly toxic environment, so anything supporting survival is beneficial. Yeast can degrade amino acids to obtain elemental nitrogen and then synthesize new amino acids and, consequently, new proteins.

However, if yeast can directly incorporate amino acids that are used in protein structures, it saves the degradation-and-synthesis step. This relates to what we call auxotrophies—and highlights the importance of knowing yeast preferences at this stage.

At LEV2050, we apply science to our nutrients

After more than 1,000 microvinifications and just as many aminograms, we gathered enough data to understand yeast nutritional needs at each stage. That science is what we embed into our nutrients.

If you want more information about our solutions in this area, click here. And if you’d like to go deeper, feel free to contact us.

Best of luck with harvest—here’s to an exceptional vintage!