Did Degassing My Wine During Fermentation Mess It Up?

I have mixed up two batches of white wine. Seems like the fermentation is taking way too long. After 12 days I went ahead and racked both batches. They continued bubbling and fermenting for 10 more days. I had to leave for vacation so I degassed both batches before leaving. This stopped the fermenting instantly. Did I mess up?
Brad — FL
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Hello Brad,
It’s not very likely that you messed any thing up by degassing your wine while it is still fermenting. Stirring a fermentation too vigorously can shock it, but it usually reorganizes itself and starts back up again.
A fermentation actually causes a slow current of activity within the wine must, with the yeast rising and falling. The yeast will hitch a ride on the CO2 bubbles being produced. Once a bubble reaches the top, the yeast fall to the bottom again. This process occurs over again and again throughout the fermentation.
When you stir or degas the wine, the fermentation process is temporarily interrupted. Under normal conditions the fermentation will show signs of life within a matter of hours.
There are such situations when degassing the wine can cause the fermentation to stop and not start back up — at least not right away. This is when the fermentation has almost finished.  It is down to its last bit of sugars. If the fermentation is degassed at that point, there may not be enough sugars to get the yeast active again.
If your fermentation does not start back up, then I would suggest that you take a hydrometer reading to see if by chance the fermentation is done. This would be indicated by a hydrometer reading of .994 to .998 on the specific gravity scale. If this is the case, there is nothing for you to do except move on to the next step of the wine making process
If you have a reading higher than .998, then this means your wine still has sugars to ferment, and you need to figure out why it is not working.
Some good information that will help you figure this out is in the article, Top 10 Reasons For Fermentation Failure. Just go through them and see if any of them ring true for your situation. Most of the 10 reasons for having a stuck fermentation have to do with the environment the yeast is in: temperature, nutrients available, etc.
As a final note, there is never a reason to degas a wine during a fermentation. The purpose of degassing a wine is to get all the CO2 gas to release. Otherwise, you will have a slightly bubbly wine — known as a pétillant.
Wine soaks up CO2 gas from the fermentation like a sponge. When it can not hold anymore it releases the excess as a gas. If you degas a wine must during a fermentation, within hours — if not minutes — the wine will become completely saturated with the CO2 gas again. For this reason degassing your wine while it is still fermenting is pointless.
Best Wishes,
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.