Low abv beer moldy?

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Well-Known Member
Oct 16, 2014
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Hi all,

A few weeks ago, I brewed a non-alcoholic beer (<1% abv). I'd done it before with good results but this time I tweaked it slightly and the OG was even lower than expected. I then pitched some old yeast. Had a taste after a week or so and it wasn't too bad but not great. Then my son was born so I never got round to kegging it for about 7 or 8 weeks!

Today I did a closed transfer to corny keg but when I opened the fermenter for cleaning there was some unusually looking stuff clinging to the sides (see pics). I'm guessing it was across the top of the beer and stuck to the sides as the level went down. I'm thinking it might be a mold because the abv of this beer would be so low. It looks a little bit like hot break material, but I think I could make out some little spots that looked like mold.

Curious to hear thoughts. Dumper?

I've had a low ABV beer do that, but not as badly. I racked it off from below the surface and left the last bit in the fermenter.
It was fine.
I suggest you taste it and smell it to determine whether or not to dump it.
I tasted it and it tastes ok but still quite sweet. I took a gravity reading and from memory, I'm not sure it has fermented. At first I thought the high FG might be because of absorption of CO2 by being at low temperature for an extended period pushing the hydrometer up, but I'm wondering if it simply never fermented! I think I might sling it.
The "quite sweet" was the feed for the mould when it was unprotected for a while.

Taste and test. But I certainly wouldn't be thinking of dumping it.

Mould is a surface issue. This is why you cook meat hot and Stilton cheese has gaps.

Tbh I had similar many years ago with 300litres of wine..... all got drunk.
I've only had one beer form a pellicle on the surface and it was fine when I bottled it.

I'd be slightly more concerned with a low abv beer though as it has less resistance against infection. If there are still sugars in the wort they might have a chance to compete with the yeast

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