I’ve had a demijohn of mixed plum wine aging away since last autum. I racked it for the hopefully the final time a while ago, then stuck it back in a dark corner to age, and forgot about it.
While packing for a trip a couple of weeks back, I noticed what appeared to be greenish and white mold floating on the top, but I was in a bit of a rush, so didn’t do anything about it at the time. It was still there when I got back, but I’ve been busy, and assumed it was spoiled, but didn’t want to throw it away without checking it wasn’t salvageable and to be honest, I kind of forgot about it. I remembered about it today, and just had a check on how bad it looked, and the mold has vanished. I took the bung out, and it smells fine.
So, any ideas what happened? Is it likely to be poisonous or something? Is there something I should do, or just bottle it and pretend I never saw anything?
I’m afraid it’s only my second try at brewing, and I messed up the hydrometer reading, so I don’t know the strength. I did write down the recipe though, if I can find it (I moved house since starting it off).
Any advice appreciated- I do understand that none of you have seen it or done a microbial survey on it, so if I want to risk it it’s my own fault if I get ill or dead.
More than likely, it’s some kind of airborne mold that ended up in your carboy before you put your airlock in, and it took a LONG time for it to grow enough to see a noticeable colony.
I’ve had this happen to beer that I’ve forgotten about in the secondary- it takes months though.
During racking it is possible to get a re-blooming of your primary yeast, or (what it sounds like here) a bloom of a secondary critter that is now able to reproduce once the primary yeast is no longer out-competing it. If you rack under nice sealed nitrogen equipment, it is probably preventable, but in my case I use the traditional “suck on a siphon tube and spill everywhere” method, so any air purity gets compromised.
Since it went away, it probably was done feeding on whatever it liked (residual sugars, oxygen, saliva backwash) and precipitated out.
Worst case is probably that you’ve probably shortened its shelf life and will need to drink it sooner.
Good to know it’s probably not serious, it’s be such a shame to have to chuck it now! I’ll try a bit tomorrow, and hopefully get it bottled soon if it tastes OK.
