Mold on surface of wine

[jvamos]

I'm making a California Cabernet, which I started last fall of '21. I put the batch through malolactic fermentation, which went fine. Then a fine white film started appearing on the surface of the wine, at the neck just beneath the airlock. I scooped away as much of that as I could with a turkey baster, re-racked and sulfited. The white mold came back. I did the same - adding more sulfite - and the mold has again formed.

I'm afraid to bottle, lest each bottle develop the same problem. The batch of sulfite I've used is a bit old - couple years. Is that the problem? Other ideas?

Any help would be much appreciated.

Jeff V.

 

[Neb Farmer]

I would definitely consider using some fresh potassium metabisulfite. That way you won't be guessing about the sulfite. And yes, sulfite got rid of that sort of problem for me, years back. I siphoned off the mold on the surface, racked the wine out and added a new dose of sulfite in the process, and that did the trick for me.
Good luck with your wine

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[Rice_Guy]

Mold is an aerobic organism, this means in the future the number one control will be to minimize ullage, top off or fill with marbles etc. On a risk basis you could also be looking at a film forming yeast. Without a microscope they will both be white films.

The treatment I have used is to remove the film with a clean paper towel(s) > add 100 ppm of K meta and then slowly layer grain alcohol (100 ml) in the ullage to “kill” any residual filaments. The bad out of this is that some folks will identify sulphite taste (burnt match). Meta has good shelf life as long as it is in a sealed container. It can react with CO2 and humidity.

Good luck on managing it.

 

[vinny]

I had gotten some K-meta in a bag with some used equipment. It was folded over and closed with a clamp. I managed to confuse the bag with one I had recently bought and noticed some writing that wasn't mine. I mixed both up with water to make a comparison and the older stuff was VERY weak in comparison to the new batch. Take a big whiff of the old one and no reason to smell the other 'cause it is stinking up the room degree of difference.