Restart a Stuck Fermentation using UVAFERM 43 RESTART™ (Preferred Method)
Last updated: 6/2021
Applies to: Winemakers needing to restart a stuck fermentation. If a fermentation becomes sluggish or you suspect it might be stuck, it is wise to get a complete picture of the wine before jumping into a full restart; See our article “Troubleshooting Stuck or Sluggish Alcoholic Fermentations.”
WHY UVAFERM 43 RESTART™?
UVAFERM 43 RESTART™ is a pre-acclimated yeast adapted to quickly restart a stuck fermentation. This yeast is the result of an innovative process developed by Lallemand Oenology using UVAFERM 43®, a strain isolated by Lallemand Oenology in collaboration with Inter-Rhône in France.43 RESTART’s resistance to stressful conditions of stuck fermentations has been naturally enhanced.
During production, an acclimation step includes addition of micronutrients, sterols, and polyunsaturated fatty acids to strengthen 43 RESTART cell membranes. These yeast cells are therefore more robust, acclimate quicker and have a lower mortality rate after inoculation than many standard yeasts.43 RESTART is sensory neutral and very malolactic bacteria compatible. It has low nitrogen needs, an alcohol tolerance of 17%, and operates well in a wide range of fermentation temperatures (55-95°F), making it a great choice to restart stuck fermentations.
WHY THIS PROTOCOL?
In previous versions of our winemaking handbook, we've published another version of our protocol for restarting a stuck fermentation. This method still works well when remaining sugar is relatively high (>3 °Brix) and alcohol is still low (<11.5% v/v). It is a great method to use with FERMIVIN® CHAMPION and UVAFERM 43®. However, UVAFERM 43 RESTART and the method discussed in this article were specifically developed to make restarts easier and work well in a variety of restart conditions.
If you'd like to use FERMIVIN® CHAMPION and UVAFERM 43®, you can use the compatible protocol, now titled the "Traditional" or Non-Preferred Method.
Prepare the stuck wine:
- step 1: Address any potential spoilage organism concerns with SO2, BACTILESS™, or lysozyme additions.
- step 2: Suspend 40 g/hL (3.3 lb/1000 gal) RESKUE™ in 10 times its weight of warm water 30–37°C (86–98°F). Wait 20 minutes then add to stuck wine. Mix thoroughly to incorporate.
- step 3: Allow the RESKUE to settle for 48 hours then rack off the settled lees.
- step 4: Adjust the temperature of the RESKUE-treated wine to 20–25°C (68–77°F).
Prepare the "Pied-de-cuve" (Starter):
- step 5: Prepare the starter with the following:
- 5% volume of racked RESKUE-treated stuck wine
- 4% of total stuck wine volume of chlorine free water
- 8g/hL (0.66lb/1000 gal) of FERMAID O™ (calculate based on starter volume, not total volume of stuck wine)
- step 6: Adjust to 5° Brix.
- step 7: Mix well.
- step 8: Add 53 g/hL (4.4 lbs/1000 gal) of GO-FERM PROTECT EVOLUTION™ and rehydrate in 20 times its weight in chlorine free 43°C (110°F) water.
- Calculate GO-FERM PROTECT EVOLUTION addition based on total wine volume, not starter volume.
- step 9: Cool solution to 40°C (104°F) and add 40 g/hL (3.3 lbs/1000 gals) of UVAFERM 43 RESTART™.
- Calculate yeast addition based on total wine volume, not starter volume.
- step 10: Wait 20 minutes and slowly acclimate the yeast before adding to the “Pied-de-cuve.”
- step 11: Maintain temperature of 20–25°C (68–77°F).
Incorporate the "Pied-de-cuve:"
- step 12: Allow “Pied-de-cuve” to drop to 0° Brix.
- step 13: Transfer immediately to the full volume of RESKUE-treated wine.
- step 14: Add 40 g/hL (3.3 lbs/1000 gal) of FERMAID O to tank. Mix to homogenize. Monitor sugar depletion throughout the restart process.