At present, a problem fermentation is only recognized once it has arisen, but it’s easier to prevent than to treat. Steps can be taken to restore yeast vitality; the success of such efforts depends on correct diagnosis of the root cause of the problem and adapted wine treatment.

Diagnosis:Careful analysis of fermentation conditions and profile provide key information on the reason for fermentation problems. Enartis Vinquiry offers a Fermentation Assessment Panel(Panel 9)that provides essential analysis to determine the cause of the problem and the degree of completion of fermentation. It includes: Alcohol, Acetic Acid, Glucose, Fructose, Malic Acid, Lactic Acid, and a Microscopic Scan.

Principal causes of stuck/sluggish fermentation and wine treatments:The conditions of fermentation, such as temperature, pH, aeration, level of solids, inoculation practices, can all impact the fermentation and lead to an incomplete fermentation.

• Nutrient deficiency: YAN, vitamins and salts determine the yeast biomass population and their activity. Proper analysis of juice composition and careful attention to yeast nutritional and physiological needs reduce the risks of fermentation arrest.
• Survival factors deficiency:sterols and fatty acids improve the yeast cells resistance to stress conditions and increases their viability. The addition of Enartis Nutriferm Advance and oxygen is recommended at 1/3 of fermentation, not later than 8°Brix.
• High Alcohol content: Alcohol participates in the disintegration of the cell membrane and reduces the yeast viability. Brix adjustment and an adapted yeast choice are necessary to deal with high Brix juices.
• Spoilage microbes can inhibit yeast growth and activity that leads to a stuck fermentation and wine spoilage. Lactic Acid bacteria can be removed by using Enartis Zym Lyso combined with SO₂. For a wider spectrum of action, Enartis Stab Micro reduces populations of spoilage yeast, lactic acid bacteria and acetic acid bacteria in wine.
• Toxins, such as residual pesticides, medium chain fatty acids, acetic acid, acetaldehyde, higher alcohols, components released from yeast or spoilage microbes, inhibit the metabolic activity of the yeast. Toxin content can be reduced with bentonite fining, yeast hulls or Enartis Celferm addition.
• Unbalanced sugars ratio: some yeast have more affinity toward fructose than others. When the stuck wine has a high fructose content, the re-start needs to be done with a fructophilic yeast, Enartis EZ FERM 44.

Regardless the cause of the stuck/sluggish fermentation, it is necessary to detoxify and treat the wine before attempting to restart the fermentation.Some types of arrested fermentations may restart without addition of yeast following this treatment. 

Re-inoculation:

• Choose an adapted yeast: resistant to high alcohol, high VA, low nutrition needs, vigorous fermenter and high implantation: Enartis EZ FERM 44
• The nutrient content in a stuck wine is inadequate to support yeast growth. Adding an appropriate yeast nutrient, such as Nutriferm Energy during the starter preparation improves yeast activity and facilitates the acclimation to the potentially hostile wine conditions.
• Acclimation by steps : follow the Enartis protocol on ‘restart a stuck fermentation’

For more information, please call (707) 838-6312.