Is this mold/contamination in secondary or yeast coming out of suspension?

[PartisanBeers]

Hi, I left a bitter in secondary to clear, which it seems to have done nicely. However, when I climbed on top of the cupboard the carboy is being kept on noticed a thin but lucid film of either mold or yeast.

I took this photo from the neck of the carboy looking into it, so its quite luminous (and looks like something from space!). Can people help identify whether this is a problem/contamination, or merely an idiosyncrasy of yeast in secondary?

Cheers!

 

[user 4295]

Unfortunately, that looks like an infected batch. Someone posted this pic a while back and said that it was acetobacter. It looks eerily similar to yours.

 

[Stauffbier]

Yup, that looks infected!

 

[PartisanBeers]

But putting on a biologists hat, that would imply that this acetobacter is going to convert the brew into acetic acid, and produce vinegar, no?

If so, I'll go for that...

 

[PartisanBeers]

Anybody know whether this will turn it to vinegar before I try? I'll add my own mother culture if not.

 

[pohldogg]

Well, that's a nice pellicle. I don't think you can tell exactly what the bug is just off the look. I've had the same strains give very different looking pellicles so I wouldn't assume acetobacter before tasting. Could be anything from bacteria to wild yeast. I'd give it a try and if it tastes good then let it sit until the new critters eat what they're going to. If it tastes bad or you don't want to sit on it for a long time then you'll probably have to dump.

 

[TimTrone]

Well, that's a nice pellicle. I don't think you can tell exactly what the bug is just off the look. I've had the same strains give very different looking pellicles so I wouldn't assume acetobacter before tasting. Could be anything from bacteria to wild yeast. I'd give it a try and if it tastes good then let it sit until the new critters eat what they're going to. If it tastes bad or you don't want to sit on it for a long time then you'll probably have to dump.

+1
You might end up with a great sour, so try it before you do anything. If it tastes good, let it sit for up to a year to do its thing.

 

[ghpeel]

That's definitely an infection, BUT it might not matter. Are you kegging or bottling? I kegged a dark English Ale recently that I dry hopped, and it developed an identical pelicle during the 5-6 days that I was dry hopping it, but it showed no off flavors in the keg and was quite tasty.

If you are bottling, then it MIGHT cause you some problems. If you do bottle, I'd recommend drinking at least 1-2 beers a week (what a shame!) to make sure they don't start over carbonating. If they do, then you could develop bottle bombs.