Fast fermentation - possible wild yeast?

[denniswnt]

I have read many assurances about wine being ok despite fast fermentation. Trust the hydrometer! But I recently had my third case in a year of fermentation quitting in about 5 days. In one case it was a kit wine that I have a lot of experience with. In the other two cases they were batches from fresh juice (one gewürztraminer, one Sauvignon blanc). In all 3 cases, specific gravity was < .995. Also in all 3 cases yeast sediment was visibly darker than typical and clearing of must was ridiculously fast (<30 days).

Is it possible there is some type of wild yeast or other contamination causing this phenomena? How would I confirm this? I am a highly experienced home winemaker (>100 batches) and am confident this is not just a "fast fermentation".

 

[TonyP]

Dennis, welcome to the forum. With 100+ batches possibly you'll be answering questions, as well as asking.

You don't say what finally happened to the wine you were making that had the possible wild yeast or other problem and that information would be good to know.

On your question, though, I'd say it is extraordinarily unlikely to impossible the kit quick fermentation you ask about was caused by wild yeast. There are two reasons I say this. First, unless you completely failed at cleaning and sanitizing to the point of having yeast encrusted equipment, it would be almost impossible for wild yeast to begin at a level necessary to multiply sufficiently in only 5 days. In other words, look at the yeast you added and compare its volume to the amount of possible wild yeast.

That's not to say it's theoretically impossible. One yeast can divide every 20 minutes. So, 1 yeast can become more than 1 quadrillion in a day.

Second though, unlike cultivated yeast, really wild yeast strains are not bred to withstand rising alcohol levels. As a result, by the time they get going, wild yeast strains would die off when alcohol levels reach 3-5%. (For all you purists, I'm excluding winery bred wild yeasts.)

Having said that, it's also unlikely (but not quite as much so) that the earlier incidents involved wild yeasts. It's possible the fresh juice could have had some wild yeast going when you bought it. However, the yeast would probably have also died when alcohol levels rose. It would be interesting to look at the juice SG levels when you started.

Let me also add that 5 days fermentation for kits is not unusual if you rehydrate the yeast and maintain warm conditions.

Finally, going forward consider where you post questions. There is a forum category covering yeast and that would have been a better place to post this.

Tony P.

 

[Arne]

First, welcome to the forum.
Second, fast ferments just sometimes happen. The temps, nutrients, s.g. and maybe the time of the moon are all just right. I really don't believe you have anything to worry about. Best of luck with them. Arne.

 

[robie]

Welcome to the forum.

I think in most cases, a fermentation with truly wild yeast is slower. They tend to not be as strong as a cultured yeast strain. It also has a lot to do with the higher volume of yeast from your yeast packet .vs. what floats into the must from the air. If you added a cultured yeast, it is not likely a wild yeast could have dominated it and done the fermentation.


The speed has a lot to do with the temperature of the must.

 

[denniswnt]

Good answers all!! Thanks very much. Although still a little concerned, I'll just chalk it up to the variability that makes home wine-making exciting.

 

[winemaker_3352]

Welcome aboard!!!

I agree with comments above...