White stuff on top of the carboy

[Hobbyist]

Hi guys,
I made 28 gallons of hard cider last fall and 3 of them started growing some white stuff (mold?) on top in the carboy after I removed the airlock (fermentation had by all appearances stopped). Does anybody has an idea what this is and whether it is still safe to drink or to at least to turn into vinegar? (The picture on the right is one without white stuff for a comparison.)

 

[fluketamer]

although i have heard of others getting drinkable cider out of there infected batches, i have never had good luck with ring around the bottle. which is what that looks like to me. ( bacterial or mold infection)

it will usually make good cooking wine tho if it doesnt taste too off.

 

[AzOr]

Taste it. It could be malolactic fermentation. In which case, your cider is fine.
If it were my batch, I’d dose it with metabisulfite as cheap insurance.

If it tastes just slightly funky, heat pasteurize and blend it with a clean cider. You may end up with a delicious cider. Some of my best ciders are blends including Brett strains.

 

[An Ankoù]

L

Hi guys,
I made 28 gallons of hard cider last fall and 3 of them started growing some white stuff (mold?) on top in the carboy after I removed the airlock (fermentation had by all appearances stopped). Does anybody has an idea what this is and whether it is still safe to drink or to at least to turn into vinegar?

It looks like a bacterial film it could be a variety that works on malic acid or one that changes alcohol. It's not uncommon, after all pressed apple juice is not a sterile medium in the way boiled wort is.
These microbes take hold after the yeast has done its job, but are not as worrying as they would be in beer since there should be no unfermentable sugars left to cause overcarbonation and burst bottles.
The main thing is to exclude air as the vinegar bacteria can't feed and multiply without oxygen. Take a gravity reading, which should be approaching 1.000 and bottle up leaving only about 2 cm headspace.
It should be fine.

 

[Hobbyist]

Thanks to everybody who replied.

 

[keystonehb]

If you are not planning on carbonating it using campden tablets will help keep it away as well.