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HELP ME, I'M STUCK!
It's never easy to accept a 'stuck' but it happens. The first thing to do is ask yourself 'why did it stick'? If you take the time to do some detective work up front, rescuing your fermentation will be easier.
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Here are some resources for pinpointing the problem
and developing a plan of action:
- Overcoming Stuck and Sluggish Fermentations - reprinted by permission from Practical Winery and Vineyard (September/October 2003).
- The ICV's 13 key points to good fermentation practices.
- Send a sample of the stuck fermentation to an oenological laboratory for evaluation. Recommended analysis: an accurate Alcohol, Microscopic evaluation, Volatile Acidity, Glucose, Fructose and Malic Acid.
Suitable products for rescuing your fermentation!
- Nutrient VitEnd - used to adsorb toxic residues
- Lallzyme LysoEasy - to inhibit gram-positive bacteria
- ProRestart - encapsulated yeast - the easiest way to handle a stuck
- Uvaferm 43 - yeast selected specifically for its ability to restart stuck fermentations - the strongest strain available!
- NatStep product - GoFerm Protect, Fortiferm or Enoferm Protect - bioavailable micronutrient and yeast sterol protectors for optimizing yeast health during yeast rehydration
- Fermaid K - added to the buildup culture to provide a needed balance of nitrogen and survival factors as well as help the rescue yeast stay suspended
How to restart your stuck?
Follow these steps before introducing the rescue yeast:
- Take the necessary precautions to avoid growth of spoilage bacteria by adding SO2 (but not so much that the rescue yeast will be impaired) and/or lysozyme. Gently rack the wine off the yeast lees to help eliminate the potential of inhibitory substances attached to the lees leaching back into the wine. Filter the wine if more practical.
- Adsorb the inhibitory substances with 25 g/hL yeast hulls. Avoid adding yeast hulls in excess of 25 g/hL as higher amounts can impart a yeasty character to the wine.
- Gently stir the yeast hulls into the stuck wine to ensure good dispersion and contact and allow them to settle for about 48 hours.
- After allowing the yeast hulls to work for 48 hours, rack (or filter if more practical). Add 25g/hL Fermaid K.
- If you know or suspect the presence of lactic acid bacteria (i.e. is the VA climbing or is the malic acid depleted?) use lysozyme.
Now you are ready to pick your strategy for introducing yeast!
Should I use ProRestart or Uvaferm 43 plus GoFerm Protect?
ProRestart is the easiest strategy but for it to be successful make sure that your wine falls within these parameters:
- Alcohol - up to 15.5% (final)
- pH - as low as pH 3
- Free SO2 - maximum 15 mg/L
- Residual sugars - will work well even below 10 g/L of sugar
- Volatile acidity - below 0.61 g/L as acetic acid (0.5 g/L as sulfuric acid)
Note: All of these parameters act in synergy with one another! It is critical to manage them together and keep the life of the yeast as easy as possible. For example, if you have a red wine with high alcohol and high SO2, facilitate an easier restart by increasing the temperature to at least 20°C and no higher than 25°C. (25°C is a higher temperature than we recommend when using traditional yeast cultures like Uvaferm 43).
Uvaferm 43 plus Go-Ferm Protect
For a traditional restart protocol using proven rescue yeast such as the Uvaferm 43 rehydrated in GoFerm Protect, we recommend one method that has been successfully used in Italy for many years and is available in the article Overcoming Stuck and Sluggish Fermentations. We're constantly evaluating improved protocols and hope to post them soon so keep checking back with us!
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