How to Stop Fermentation in Winemaking
One of the greatest challenges in winemaking is stopping the fermentation. Fermentation is caused by the yeast which consumes the sugars from the wine and turns them into alcohol.
The fermentation process generally stops on its own when there is no sugar left, so you will have a really dry wine, or when the alcohol concentration reaches about 14-18%, depending on the yeast strain.
However, the question about how to stop fermentation in winemaking rises when your wine reached the desired level of sweetness and you want to keep it just as it is.
So, let’s see how to stop fermentation with three simple methods.
1. Stopping the Fermentation with Cold Shock
This is the only method that has no influence on the flavor, potency and aroma of the wine you’re making. The method is very simple, basically, you have to cool your wine to a temperature that causes yeast to stop its activity and precipitate on the bottom of the demijohn.
To stop the fermentation, follow these steps:
- Place the wine in a very cold room or in a refrigerator, at 36-50 degrees Fahrenheit, for 3-5 days. If you leave the wine in a cold warehouse, pay attention to the temperature at all times because it is essential that it stays above the freezing poi
- During this time the fermentation will completely stop and the yeast will precipitate. You will notice the sediment on the bottom of the demijohn and a partial clarification of the wine.
- Remove the sediment by racking the wine into another sterilized demijohn. This operation should be made a temperature of 61 degrees Fahrenheit or less.
- Filter the wine through a wine filter into another sterilized demijohn.
- Leave the wine at normal temperature for at least a week and check on it daily. If you notice any signs of fermentation, repeat the process.
The downside of this method is that some of the yeast can be filtered with the wine during the racking process and the fermentation will start again. You can prevent this by adding about 0.14 oz. of sulfur trioxide to each 2.6 gallons of wine. However, these preservatives will lower the quality of your wine.
2. Stopping the Fermentation through Pasteurization
Probably the most efficient method for killing the wine yeast is the pasteurization. Yeast normally dies at temperatures above 104 degrees Fahrenheit, so to stop wine fermentation it is sufficient to heat the beverage above that point.
Here is how to stop fermentation with this method :
- Rack the wine into a sterilized pot.
- Heat the wine to about 158 degrees Fahrenheit and maintain this temperature for about 10-20 minutes. This will kill not only yeast but also other organisms present in the wine.
- Cool the wine down to 50-61F° as quickly as possible.
- Bottle the wine immediately and seal it hermetically.
Alternatively, you can rack the wine directly into the bottles, pasteurize the bottles then seal them.
The downside of this method is that it is difficult to maintain a constant heat for 15 minutes and it is difficult to cool the wine quickly enough.
This process will alter the wine’s flavor and in order to be effective, you should minimize as much as possible the contact of the wine with the outside environment after pasteurization.
3. Stop the Fermentation with Alcohol
This is probably the simplest way to stop fermentation in winemaking. As we already told you, yeast stops its function when the alcohol concentration is about 16%. Actually, depending on the yeast strain, the alcohol concentration can be between 14% and 18%.
So you can stop wine fermentation by simply adding more alcohol to your wine. This is how to do it.
- Rack the wine into a sterilized demijohn, in order to remove all the sediment from the wine.
- Add alcohol to the wine until you reach a concentration of about 16%. The alcohol should be either grape distillate, vodka or brandy.
- Leave the wine for another week and see if you notice any sign of fermentation. If you don’t, you can rack the wine one more time, then proceed to bottling.
The downside of this method is that the added alcohol will not only alter the flavor but if you use vodka, it will also give an unpleasant smell to the wine.
Have you ever stopped wine fermentation before? What method did you use? If you have any questions or tips on how to stop fermentation in winemaking, please leave a comment below.