Restart a Stuck Fermentation ("Traditional"/Non-Preferred Method)
Last updated: 9/2022
Applies to: Winemakers looking to restart a stuck fermentation with a yeast other than UVAFERM 43 RESTART™ (including FERMIVIN® CHAMPION and UVAFERM 43™). This protocol works best when when remaining sugar is relatively high (>3° Brix) and alcohol is still low (<11.5% v/v).
WHEN TO USE THIS PROTOCOL
The method in this article, the non-preferred or "traditional" method, works 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, Our recommended restart method uses UVAFERM 43 RESTART and can be found here. UVAFERM 43 RESTART™ and that method were specifically developed to make restarts easier and work well in a variety of restart conditions.
WHAT TO ADDRESS BEFORE RESTARTING
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. Sometimes a simple adjustment or a mixing can be enough to get a fermentation back on track. See our article “Troubleshooting Stuck or Sluggish Alcoholic Fermentations.”
Unwanted bacteria like Lactobacillus spp. and Oenococcus oeni are often present in stuck fermentations. Adding Lysozyme to the stuck wine prior to restarting the fermentation may help control unwanted bacteria and provide an improved environment for the restart to occur. Adding RESKUE™ to the stuck wine prior to restarting the fermentation may also help reduce accumulated toxins and improve chances for a successful restart.
When restarting a sluggish or stuck fermentation, it is essential to address yeast biomass buildup together with the low nutrient levels. A yeast rehydration nutrient such as GO-FERM PROTECT EVOLUTION™ is essential, as it is rich in micronutrients and survival factors. When stuck wines have high residual sugar levels, the addition of a complex nutrient to the stuck wine is also recommended. Another important note is to pay attention to the starting Brix of your restart and follow the protocol below accordingly.
Build Up for Stuck Wine:
- step 1: Add 40 g/hL (3.3 lb/1000 gal) of RESKUE 48 hours prior to restarting.
- step 2: After 48 hours, rack off the RESKUE.
- step 3: Add a complex yeast nutrient (FERMAID O™ or FERMAID K™) directly to the tank of stuck wine at a rate of 0.5–1.0 lb/1000 gal (6–12 g/hL). Many winemakers also add Lysozyme at this time to reduce potential bacteria problems.
- step 4: In another clean container mix equal volumes of stuck wine and water. Generally, this would total 1% of the total wine volume. (Example: For 1000 gal of stuck wine, use 10 gal water + 10 gal wine.) This container will be the “Mother Restart Tank”.
- step 5: Calculate the amount of GO-FERM PROTECT EVOLUTION at the recommended rate. Dissolve this yeast rehydration nutrient in 20 times its weight of clean, chlorine-free, 43°C(110°F) water. (Example: 5 lb GO-FERM PROTECT EVOLUTION x 20 = 100 lb, divided by 8.33 lb/gal water = 12 gal water needed.) Mix the solution.
- step 6: Select a yeast strain that is both alcohol tolerant and a vigorous fermenter such as UVAFERM 43™, LALVIN K1 (V1116)™, FERMIVIN CHAMPION or VIN 13. Calculate the amount of yeast required for the total volume of stuck wine at 3–5 lb/1000 gal (36–60 g/hL). When the rehydration nutrient/water solution temperature has cooled to 40°C (104°F), slowly (over 5 minutes) add yeast. Stir gently to mix and avoid clumping. Let this yeast suspension stand for 20 minutes.
- If using GO-FERM STEROL FLASH™, temperature acclimation is not needed and the yeast can be added directly to the cool rehydration nutrient/water.
- step 7: Check the temperature of the yeast suspension. There should not be more than 10°C (18°F) difference between the yeast suspension and the diluted wine in the Mother Restart Tank. If there is too great a temperature difference, acclimatization may be required. Cold temperatures may shock the yeast cells.
- step 8: When the yeast suspension is properly rehydrated and proper consideration has been given to temperature differences, add the yeast to the Mother Restart Tank and wait 20–30 minutes.
Inoculation of Stuck Wine:
- step 9: Add 10% of stuck wine to the Mother Restart Tank and wait 20–30 minutes. (Example: For 1000 gal stuck wine, add 100 gal wine.)
- step 10: Add 20% of stuck wine to the Mother Restart Tank and wait 20–30 minutes. (Example: For 1000 gal stuck wine, add 200 gal wine.)
- step 11a: Repeat step 10.
- step 11b: Repeat step 10.
- step 11c: Repeat step 10.
- step 12: Add any remaining wine to the Mother Restart Tank.
Protocol Changes Based on Starting Brix:
>3°Brix & <11.5% Alcohol
- Follow the protocol as written
- Follow this restart protocol, except in Step 3 reduce the complex yeast nutrient addition to 0.5 lb/1000 gal (6 g/hL).
- Follow this restart protocol, except in Step 3 eliminate the addition of a complex yeast nutrient.