The Importance of Yeast Rehydration Nutrients

Last Updated: 1/2023

Applies to: those looking for a better understanding of what happens during yeast rehydration and the function of rehydration nutrients. Especially important for producers looking to increase speed of fermentation and winemakers looking to enhance aroma.


GO-FERM™, the first yeast rehydration nutrient, was introduced over 20 years ago and it revolutionized the way we think about fermentation. It improved fermentation kinetics and helped avoid fermentation problems.

Since then, the GO-FERM line has expanded to include GO-FERM PROTECT EVOLUTION™ and the new GO-FERM STEROL FLASH™. These next generation nutrients maximize aromatic expression in addition to improving fermentation kinetics and avoiding fermentation problems.

The Function of Rehydration Nutrients

GO-FERM PROTECT EVOLUTION™ and GO-FERM STEROL FLASH™ are important because they provide sterols, unsaturated fatty acids (UFAs), vitamins, and minerals that yeast need. These compounds prepare the yeast to withstand the osmotic stress of juice/must and the alcohol and temperature stress of fermentation. They can also help yeast release bound varietal aroma compounds present in grapes and can stimulate ester production. While grapes naturally contain vitamins, minerals, and sterols, there are often not enough to support healthy fermentations, leading to stuck or sluggish fermentations.

Our rehydration nutrients are made from selected strains of autolyzed yeast and are developed to efficiently supply yeast with necessary compounds. Added during rehydration, rehydration nutrients exploit a narrow window of time when yeast cannot control what goes in and out of the cell. Because yeast cannot control what goes in and out of the cell, vitamins, minerals, and sterols are directly incorporated into the cell.* Additionally, when these compounds are added during rehydration, they are fully available to yeast because they are not consumed by native microflora or bound to other juice/must compounds.

*Harmful substances can also be incorporated into the cell at this time. We recommend rehydrating in clean water and GO-FERM only. Rehydrating in juice/must or using other nutrient formulations (e.g., DAP) during rehydration may harm yeast.

The Role of Sterols, Vitamins, and Minerals

Read on for a deeper dive about how yeast cells use the sterols, vitamins, and minerals from rehydration nutrients.


Sterols and unsaturated fatty acids are incorporated into the yeast cell membrane. They provide membrane stability, maintain intracellular pH (important for enzymatic activity) and prevent unwanted diffusion of alcohol and other juice/must components that are toxic to the cell. Sterols also prevent transport proteins from denaturing, which is critical to the uptake of sugar, nitrogen, minerals, and aromatic precursors. Because of this, sterols are positively linked to increased aromatic expression.


Vitamins are growth factors that affect cellular multiplication and metabolic functions. They are linked to fermentation rate and fermentation byproduct formation.

  • Biotin is a cofactor for multiple enzymatic reactions in carbon and nitrogen metabolism and is associated with increased cell viability and ester production and decreased off-odor production.
  • Pantothenic Acid helps avoid the production of hydrogen sulfide (H2S). Pantothenic acid helps yeast produce Acetyl-CoA which allows the complete metabolism of sulfur-containing amino acids, limiting the production of H2S, an intermediate compound the process.
  • Thiamine is associated with improved fermentation kinetics and increased yeast biomass, while deficiencies can be linked to stuck fermentations. Thiamine helps with specific enzymatic reactions (decarboxylation reactions) that affect the efficiency of carbon and nitrogen metabolism.


Magnesium, zinc, and manganese are essential to yeast because they are cofactors for innumerable enzymatic reactions that cannot happen without them. They are needed for growth and carbohydrate metabolism, and they help offset the detrimental effect of heavy metals, ethanol, heat shock, and osmotic stress, maintaining cell vitality under stressful conditions

Learn More

Check out our article "Yeast Rehydration Is Better Than Direct Inoculation" to learn more about the importance of the rehydration process.
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