Restart a Stuck Fermentation using UVAFERM 43 RESTART™ (Preferred Method)
Last updated: 10/2024
Applies to: Winemakers needing to restart a stuck fermentation. Contains a printable pdf download of the protocol and accompanying worksheet.
DownloadWHY UVAFERM 43 RESTART™?
UVAFERM 43 RESTART™ is a pre-acclimated yeast adapted to quickly restart a stuck fermentation. 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.
In previous versions of our winemaking handbook, we've published another restart protocol. That protocol works well with FERMIVIN® CHAMPION or UVAFERM 43® when remaining sugar is relatively high (>3 °Brix) and alcohol is still low (<11.5% v/v). In most situations, the protocol detailed below is preferred.
Protocol
Prepare the stuck wine:
These steps mitigate spoilage organisms and remove some toxic compounds commonly present in stuck wines. Toxic compounds are frequently produced by stressed yeast during a stuck ferment and can inhibit a restart if not removed.
- step 1: Add SO2 or a 25 g/hL addition of BACTILESS™ or Lysozyme if spoilage bacteria is a concern. (Do not use BACTILESS in this step if malolactic fermentation hasn’t completed but is desired.)
- step 2: Add RESKUE™ by suspending 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.
- step 4: Rack and adjust temperature to 20–25°C (68–77°F). Note new volume after racking.
Prepare the starter mixture:
When adding yeast to a stuck wine environment with high alcohol and low sugar, yeast must be very carefully acclimatized so they can successfully complete fermentation. These steps prepare a wine mixture that is lower in alcohol and higher in sugar than the stuck wine, which will help slowly acclimate yeast.
We recommend adding water and sugar (cane sugar, grape juice concentrate, or grape juice) to maximize success. There are state and federal regulations that address adding sugar and water during the winemaking process. Please check applicable regulations to ensure compliance.