Troubleshooting Sluggish and Stuck Fermentations
Could you get back on track without a restart?
There are several factors that affect the success of fermentation and sometimes a small adjustment can get things back on track without the need for a full restart. Below we outline some common causes of problematic fermentations and advice for next steps.
TEMPERATURE STRESS
Each yeast strain has an optimal temperature range and anything outside of this range can cause yeast stress. If the temperature is too high (or if it spiked at any point), it’s possible the yeast are no longer viable and a restart is necessary. If the temperature is too low, try slowly warming the wine to 70°F (+/- 2°F).
ALCOHOL MAY BE TOO HIGH
Certain yeast strains can tolerate more alcohol than others. If you have exceeded the tolerance level of your selected strain, you may need to reinoculate with a strain that has a higher tolerance or try a restart.
WINE MIGHT NEED DETOXIFICATION
When wine yeast become stressed, they can produce compounds that impede fermentation. RESKUE™ can be extremely beneficial if this happens. Add RESKUE and mix thoroughly, then rack after 48 hours. If you are unable to rack, adding RESKUE and leaving it in the wine can still help.
MICROBIAL COMPETITION
Lactic acid bacteria (LAB) can produce volatile acidity (VA) and inhibit yeast activity. To control LAB, use lysozyme (if MLF is desired) or BACTILESS™ (if MLF is complete or undesired). In any condition, uncontrolled LAB should be controlled before trying to restart a stuck fermentation.
NEED TO RESTART?
Check out our detailed protocol and calculation worksheet for restarting stuck fermentations using UVAFERM 43 RESTART™. If you've tried this protocol in the past, this version is NEW as of 2024 and is simpler and easier to understand.