Film yeast or?

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Josh Monop

Oct 23, 2018
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Hello everyone! First time post here, and I am having an issue I hope I can sort out. I am a chef and i make wines specifically to turn into vinegar, Many fruit(and vegetable) based.

Anyhow, I have a roasted pumpkin wine that I am trying to convert to vinegar, but it seems to continue growing what looks like film yeast and the vinegar mother can't seem to take over.

I strained the batch through filters and got most of what I saw in the bucket out. Out of worry, I put some in a fresh sanitized bucket to see if it would happen again, and the rest in a glass jar. The bucket is covered in cheesecloth(as oxygen is needed to convert to acetic acid) and the glass jar is sealed. A few days later and the film is back on the batch in the bucket. Nothing formed on the wine in the sealed jar. Any thoughts on what it is and how to get rid of it, without drastically altering everything about It? Do I need to get rid of it and start over?

Thanks for any suggestions/input and I look forward to getting to know this forum!




Veteran Wine Maker
WMT Supporter
Jan 1, 2007
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looks like you are fighting a battle with a film bacteria that also use air to propagate. it will eat the alcohol fro the top down and just leave flavored water behind. My first thought is to check the ph but I don't know what is the best ph for vinegar. since I make wine vinegar for salad dressing also I would guess the ph value has to be in the range 3.1-3.6. the film yeast may enjoy a ph above this value I presume these number as they are values similar to wine making ph's. so my guess is adjust the ph value. if not good idea start over.


Veteran Winemaker
Jun 16, 2014
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I'm certainly no vinegar expert, though I spent a fair amount of time researching how to keep it out of my wines. Did you use a mother to start the vinegar process? Wine exposed to air will eventually form a bloom on the surface, but the type of organism depends on the conditions, temperature, pH, alcohol content, etc. Most information I have indicates that low alcohol wines below 5% are more susceptible to film yeast and will tend to favor them over vinegar bacteria. Once you have a batch that turns out with good vinegar, save the mother for use on subsequent batches.
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