Although this topic is rarely discussed, stopping wine fermentation is one of the biggest challenges you’ll face in wine-making. But the good news is that it is possible to stop this process. Wine fermentation occurs when yeasts convert the sugars in wine into alcohol.
Generally, the fermentation process stops when the yeasts have used up all the sugar, leaving you with an extremely dry wine. If, on the other hand, the wine’s sweetness has reached the level where you want it to stay, then you’ll need to halt the fermentation process. This article will show you four effective ways to stop fermentation in wine.
What Is the Wine Fermentation Process?
Understanding how fermentation works will help you better understand how the “fermentation termination” process works. In a nutshell, fermentation is the process through which grape juice turns into wine. In its broadest meaning, fermentation is the enzymatic transformation of sugar by yeasts into carbon dioxide and alcohol.
We often hear about the wine fermentation process, but people hardly talk about its termination. Why? Because the termination process goes against the way things usually work. The fermentation process naturally stops on its own. Therefore, controlling the process might not be how things work naturally, but it is possible.
So, regardless of your reason for wanting to stop the wine’s fermentation, one or two of the following methods will certainly do the trick.
4 Ways to Stop Wine Fermentation
Manipulating wine fermentation once the process starts is very tricky. Therefore, note that there is no one-size-fits-all method for managing or stopping it. Each of the termination methods we’ll show you has its pros and cons.
The key to finding the suitable termination method is figuring out what positives you’re looking for and what downs you’re willing to accept.
With that, here are the four best methods for stopping fermentation in wine:
The first fermentation termination method we’ll discuss is using “Sulfites.” Keep in mind, though, that this method is most useful for fermentations nearing completion. Therefore, you shouldn’t use sulfites to stop vigorous fermentation.
Adding Sulfites Method
Wait until the wine reaches the target sugar level and add sulfites. You can determine your wine’s sugar level by using a hydrometer. Sulfites commonly used in winemaking include potassium metabisulfite, potassium bisulfite, sodium metabisulfite, and Campden tablets.
Next, bring the temperature down to below 40°F to further inhibit fermentation. Doing this will stifle any remaining yeast activity and terminate the fermentation process. However, our job here is ongoing. A wine that hasn’t finished fermenting and still has some sugar has to be stabilized.
What this means is that we need to prevent the surviving yeast cells from reproducing and restarting the fermentation process. While we’ve terminated one fermentation process, another can begin since the remaining yeasts can feed on the excess sugar and breed.
Therefore, we must inhibit further yeast growth by adding a stabilizer called “potassium sorbate.” The job of the potassium sorbate is to make the yeasts sterile, so they can’t reproduce and start working again. In case you were wondering, “why didn’t we add this chemical from the start to stop the active fermentation?”
That is because potassium sorbate works only to prevent further fermentations from occurring. First, the sulfites kill as much yeast as possible, and then, the stabilizer renders the remaining ones sterile.
The term “cold shock” refers to lowering the wine’s temperature to put the fermenting yeast to sleep. And this is also an excellent method for preserving yeast for subsequent re-pitch, preventing the waste of an otherwise usable batch.
When done correctly, cold shocking is the best method for stopping fermentation in wine while preserving its aromatic profile and natural flavor. Here’s how to cold shock your wine.
Cold Shock Method
The first step is to harvest your grapes and crush them. Then, allow the grapes to sit with the skins for at least 24 hours. Strain off the liquid from the solids and then add yeast to the liquid.
Next, ferment the must at a cool temperature, preferably around 50°F, to allow for a more gradual fermentation. Primary fermentation usually lasts about five days, so wait for the process to complete. You will be able to tell because the yeast sediment will have settled at the bottom of the container.
At this point, you should cold shock the wine instead of starting the secondary fermentation process. And to do that, First, sanitize a new container and rack your wine. Filter out all the yeast sediment and save it for future use.
The next step is to move your vessel into a room where the temperature is lower than 40°F but higher than 22°F. Keep in mind that we don’t want the wine to freeze. If the wine freezes, it’ll lose its aroma and flavor. Plus, the alcohol will separate from the juice.
Leave the wine in the colder room for a few more days. Finally, rack and filter the wine again. Move the wine to a new sterilized container and filter it to remove any yeast sediment that may still be present.
After that, allow the wine to sit out for a week or so at room temperature, with daily checks. If you missed some yeast and fermentation resumes again, you could fix that by giving the wine another shock.
You can also stop wine fermentation by adding alcohol, a simple and effective method. This termination method is known as “Fortifying.” This termination method works because high concentrations of alcohol kill the yeast. On the downside, this method requires a high level of blending expertise to prevent the wine from being ruined.
The upside is that this method has been proven to be effective time and time again. Regarding the amount of alcohol one should add, that depends on the wine itself. Generally, the yeast in wine will stop working when the alcohol level reaches about 16%.
As a matter of fact, the alcohol content can vary from 14% to 18%, and that depends on the yeast strain used.
Adding Alcohol Method
- First, allow the primary fermentation to take place
- Next, rack the wine for the first time and then add alcohol to kill any leftover yeast. That’s it
Note: the resulting wine will be on the sweet side and have a high alcohol by volume (ABV) percentage.
Rack the Wine
Racking is the process of transferring wine from one storage vessel to another. Here, you’d be working to free the wine of sediments. The goal is to get rid of the sediments together with the yeasts, thereby halting the fermentation process.
On the upside, this method is easy and won’t take much of your time. However, its downside is that it is not as effective as the other termination methods we’ve covered here. Still, don’t cross it out of your list just yet. However, combining this technique with other termination methods can improve outcomes.
How sweet or dry your wine turns out depends on how long you allow it to ferment. If you want a dryer wine, let the fermentation process naturally progress. However, if you wish for an off-dry or a “slightly sweet style” wine, you’ll have to manipulate the fermentation process.
You can stop fermentation in wine by doing a cold shock, racking it, or adding alcohol. Another great way to stop fermentation in wine is by adding sulfites. Overall, choose a termination method you are confident using so you can achieve the wine’s desired flavor and aroma.