Why Is Stirring A Fermenting Wine So Important?

Stirring Fermenting WineI have started making 5 gal of Blackberry wine and I am using your ingredients. One question is in your wine recipe you say after the first day add the yeast with the fermentation bag still in the must and leave it for an additional 7 days before transferring it to the carboy. Should I continue to stir the wine also ? Do I need to add make up water after removing the bag ?

Name: Charles P.
State: SC
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Hello Charles,

Once you add the yeast you will want to stir the fermenting wine must around as much as you can. The goal is to not allow any of the pulp to become too dry during the fermentation. Stirring it around once or twice a day should be sufficient.

In a winery they call this punching the cap. When fermenting grapes there is so much pulp involved that a thick solid cap is formed. The winemaker has to punch it down with a punch down tool that looks similar to a large potato masher with a long handle.

With your fermentation there is much less pulp. I’m assuming you used around 15 pounds of blackberries to make your five gallons, whereas with a grape wine there would be about 40 pounds, so simply stirring the fermenting wine should be sufficient in your situation.

If you have our regular size fermentation bag, just open it up and stir the pulp so as to circulate the dryer pulp towards the bottom. Rotate the pulp. If you have our jumbo fermentation bag, then it should be left open and rolled backwards over the brim of your primary fermenter. All you need to do is give the pulp a quick stir in kind of a folding manner.Shop Fermentation Bags

The reason you want to keep stirring the wine must is twofold. The first one is simple. When the pulp becomes to too dry for too long of a period, it provides a perfect place for mold an bacteria to grow – damp, nutritious pulp that is exposed to air. The second reason is if a solid dry layer forms it will interfere with the fermentation. Wine yeast needs air to successfully grow and multiply into a large enough colony to support a healthy, vigorous fermentation. If a dried cap forms it creates a barrier that traps the CO2 gas in the wine must and cuts the air off from the yeast.

As you suggested, once your primary fermentation is done and you are ready to remove the fermentation bag, there will be some loss in volume, but it will not be as much as you might think with your blackberries. What you are looking at now is the plump fruit. Once the fermentation gets hold of it, it won’t be so plump. The fermentation will break down the pectin in the blackberries making the pulp just a shell of what it was before.

If you do find your batch is excessively short then you should top up the wine when going into secondary, but is should not be a major issue. Just be sure to get as much liquid as possible when racking into your secondary fermenter — even if some sediment is coming along with it. Also, when you pull the fermentation bag out, wring it as best you can. The more juice the merrier.Shop Stirring Paddle

Charles, I hope this answers your questions about stirring fermenting wine. Just remember that stirring the wine must daily to keeping any cap from becoming hard and dried is a critical part of having a healthy, active fermentation.

Happy Winemaking,
Ed Kraus
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Ed Kraus is a 3rd generation home brewer/winemaker and has been an owner of E. C. Kraus since 1999. He has been helping individuals make better wine and beer for over 25 years.

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