Moldy film on top of ferment

[Theodosios]

Hi Everyone,

Just finished bottling my second ever all-grain batch.

Problem: both batches developed a thin layer of mold or impurities on the top, along with big bubble (that remained unpopped), late into the secondary fermentation. The first batch developed a kind of horrible, rubbery odour.

The other day I added more water to the carboy to have the gucky film overflow and pour out. It otherwise smells and tastes okay. Any idea what's causing this? Strange that it's twice in a row! Pretty sure I sanitized thoroughly.

Thanks in advance,

Theo

 

[Kriznac]

Without pictures it's hard to be 100% certain, but it sounds like a normal fermentation. If you have an off white foam with a thin layer of brown "crud" on top of that then no worries, it's just yeast and is totally normal. And remember, if it tastes good it is good.

 

[RIT_Warrior]

Hi Everyone,

Just finished bottling my second ever all-grain batch.

Problem: both batches developed a thin layer of mold or impurities on the top, along with big bubble (that remained unpopped), late into the secondary fermentation. The first batch developed a kind of horrible, rubbery odour.

The other day I added more water to the carboy to have the gucky film overflow and pour out. It otherwise smells and tastes okay. Any idea what's causing this? Strange that it's twice in a row! Pretty sure I sanitized thoroughly.

Thanks in advance,

Theo

I actually bottled a recipe with a similar problem about a week ago. It smells and tastes fine, but it had a strange film on the top. It was a chocolate stout, so I figured the film was oil from the cocoa powder I used was causing the film. The film also had a rather alarming greenish tint to it which made it look sort of moldy, but as I can't smell or taste anything wrong I figure it is OK.

It does seem a bit odd that you would add water to the carboy, though. Wouldn't that water down the beer? Or maybe I'm misunderstanding you.

The bad smell is probably a bad sign, but I'd give that batch some time before rendering a final verdict.

 

[Efusco]

I actually bottled a recipe with a similar problem about a week ago. It smells and tastes fine, but it had a strange film on the top. It was a chocolate stout, so I figured the film was oil from the cocoa powder I used was causing the film. The film also had a rather alarming greenish tint to it which made it look sort of moldy, but as I can't smell or taste anything wrong I figure it is OK.[\quote]

wow, that is so reassuring! I've had a chocolate stout in secondary for about a week and a half. I peaked under the towel covering the carboy and saw a very thin bluish film I took to be mold. Hopefully it is just residue from the cocoa powder as you are surmising. May bottle this weekend though, just to be sure.

 

[MattGuk]

Sounds like a pellicle to me, i have had it a couple of times and i smelled nasty.
I bottled it as soon as i saw it, racking from underneath and the beers turned out fine.

 

[Bryceefisher]

I can almost be sure it is an infection. Sounds like a pellicle. Does this look familiar? Found it on Google images. Never had an infected batch until today when I pitch a sour mix.

 

[Efusco]

Following up. I did bottle that batch this weekend. It smelled and tasted fine to me. When I racked the beer out of the carboy a thin light brown coating clung to the side walls, but otherwise the beer came out very clean looking.

Perhaps this is a side effect of the cocoa powder?


Sent from my iPad using Home Brew

 

[jro238]

It is really hard to tell without a picture. Your initial description sounded a little like an infection but your "thin light brown coating clung to the side walls" description sounds completely normal. The brown crud is just fallen krausen and any green stuff you see is more than likely just left over hop debris.