Bad Batch

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edgewoodbrewery

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Ok, Looking for some troubleshooting here. I'm not a new brewer, but this is the first batch I've ever had go bad. I did a smoked oatmeal stout. Primary for 3 weeks, secondary for a month and a half. Went to bottle it and it had a very strong vinegar/balsamic vinegar smell. Any Ideas? Questions are welcome too! Thanks.
 

lamarguy

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Acetobacter

Check your sanitation techniques and thoroughly sanitize all of your equipment to prevent infecting future batches. I would recommend something strong, like bleach. Just be sure to rinse well afterwards.
 

Saccharomyces

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Acetobacter requires two things to sour a beer and make vinegar (acetic acid):
- ethanol (plenty of that in fermented beer)
- oxygen

The primary and secondary *should* be closed systems, so there shouldn't be enough oxygen available for acetobacter to do much damage even if you get it in there. I would look at your whole system end to end to figure out how the oxygen got in. It's likely whatever pathway was there for oxygen is how the acetobacter got in as well. Fruit flies carry a lot of acetobacter on their bodies, it only takes a few of them getting in to spoil a batch.
 

ifishsum

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Acetobacter requires two things to sour a beer and make vinegar (acetic acid):
- ethanol (plenty of that in fermented beer)
- oxygen

The primary and secondary *should* be closed systems, so there shouldn't be enough oxygen available for acetobacter to do much damage even if you get it in there. I would look at your whole system end to end to figure out how the oxygen got in. It's likely whatever pathway was there for oxygen is how the acetobacter got in as well. Fruit flies carry a lot of acetobacter on their bodies, it only takes a few of them getting in to spoil a batch.

Interesting, the only infected batch I have ever had was very vinegary. I secondaried that batch (2.5g) in a Mr. Beer keg (no airlock but a vented lid system) and there was indeed a couple of fruit flies that somehow got in there. That answers a lot...I bleach soaked that keg and boxed it back up, swearing to never use it again.
 
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edgewoodbrewery

edgewoodbrewery

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Hmmm... I'm guessing maybe our sanitation might be the problem. Used Carboys with airlocks that were good. Another thing that I've been puzzled by is this- When we removed the airlock bung, there was a small ring of white residue right where the bottom of the bung stops on the glass neck. I wasn't sure what it was or if maybe it might be some dried sanitation water that the stopper was soaking in right before it was inserted. Any Ideas?
 

Nugent

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Same thing happened to me recently. Lovely oatmeal stout also.

Cracked my first bottle - vinegar!

Dumped the works except four bottles. Gonna leave them for a while and see what happens.

Pain in the a**.
 
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