How to Kill Yeast in Wine
So, you’re trying to figure out how to kill yeast in wine. Why? Perhaps you want a sweeter wine. Maybe you need to leave your wine for an extended period of time and you don’t want to leave it fermenting. Whatever the reason, there are several approaches you can take to get this job done.
Why Kill Yeast in Wine?
First, the only reason to kill yeast in wine is to stop fermentation. It is important to note that this approach to winemaking is not normal.
You should not ever need to stop fermentation and kill the yeast in your wine.
In fact, in most cases, you will want to collect the yeast cells after fermentation and use them again. Yeast can get expensive! And since you can use the same batch several times before the cells die off, you should absolutely preserve what you can.
In an ideal situation, your wine will ferment for anywhere from five days up to two or three weeks. During this time, the must, rich with sugars, will attract the yeast cells. The yeast cells will then get right to consuming those sugars.
During fermentation, the yeast will start bubbling and foaming up the must, creating a cap over the wine that blocks out oxygen and releases carbon dioxide.
When the yeast has completed fermentation, that cap settles back into what is now wine, and the yeast cells do a cleanup of any dead yeast cells in the wine as well as any enzymes leftover that may be creating off flavors.
When you stop fermentation by killing your yeast cells, you run the risk of interfering with this process. In short, you could end up with off-flavored wine.
Still, the end result of most wine fermentation will be that the yeast has consumed all the sugar, leaving you with a dry wine.
If you’re hoping for a sweeter wine, you might think about stopping fermentation before the yeast can consume all the sugar.
And that is likely what you will get. Just be aware that, in addition to potential off flavors, you will also get a lower ABV, as the yeast did not get to ferment those final sugars into alcohol.
Now, if you’re okay with all of that, you can take one of several approaches.
How to Kill Yeast in Wine
Sulfites
The first step many novice winemakers want to take to kill the yeast in wine is to add sulfites. While an excess of sulfites will indeed kill off any yeast in your wine, you also run the risk of chemically altering the state of your wine, and therefore affecting its flavors and aromas.
If you do decide to use sulfites, just be sure to keep your ratio down to 4 to 10 Campden tablets per 5 gallons of wine, and make sure you chill the wine to 44 degrees Fahrenheit at the absolute warmest.
You need the wine to be chilled to settle the yeast down and prepare it to be killed off. You’ll also want to add ¼ teaspoon of potassium sorbate, which will ensure that any remaining living yeast cells cannot reproduce.
Boiling
Everyone knows too much heat will kill alcohol. Well, this is also true of yeast, and it is true at a much lower temperature. If you go this route, you will need to bring the wine up to 140 degrees Fahrenheit, but no higher. If you go too much higher, you will ruin the wine and kill the alcohol.
It is also critical to point out that heating wine will likely alter the flavor, the aroma, and the texture of the wine. Thus, this approach is the least favorite of winemakers.
Alcohol
If you’re trying to stop fermentation to allow for sweetness, but you want to increase the ABV, you can always fortify your wine. Adding liquor to your wine during fermentation will halt the process and give you a dessert wine effect.
In most cases, you will add brandy or whiskey, which will kill off any remaining yeast in the wine.
Racking
Finally, the favorite approach of winemakers by far if you must stop fermentation is simply to rack the wine. Racking wine simply involves transferring the wine from one vessel to another, filtering out the yeast with a wine filter.
With this approach, you don’t actually have to kill the yeast at all. You can collect it and use it again at a later time.
Be sure you chill the wine first, which allows the yeast to settle down and prepare to be collected.
In the end, if you’re trying to kill the yeast in wine without altering the flavor and aroma of the wine, you are in for a challenge. Each approach you take will result in altering the natural process of fermentation, and you will likely find yourself with at least a slightly altered version of the wine that was being produced.
Still, if you hope to stop fermentation, your best bet is going to be chilling and racking it. And in this case, you will end up ahead, with a sweeter wine and yeast cells that are alive and well and ready to get back to work.
Cheers!
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