# Vinegar Smelling Ferment



## Krew (19/8/11)

Hi everyone,

I've been at this lark since Xmas (best present ever!!), and have got most of the information I need from searching this fantastic resource and some other sources. This one has me a bit more stumped though as it involves chucking away beer- which is proving harder to do than I expected!

I have a Muntons Yorkshire Bitter that has been down for the last 12 days, and has been stinking out the brew fridge with an obnoxious vinegar odour from about 5 days into the ferment. Its a normal kit and kilo job, using safale s-04 yeast at 18 degrees, everything the wort touched was sanitised in Sterophos for at least 4 hours. The OG wasn't taken as the hydrometer was bust (and don't those little black beads just get everywhere!!), and the FG has been sitting on 1014 for the past few days. This is my first infection, so I can't complain.

Everything tastes and looks normal, maybe slightly sourer than the previous efforts at this brew, but the top of the brew looks fine, it maybe a touch cloudier than normal, but nothing that a rack and cold condition won't settle out.

I popped into the LHBS and his advice was to taste it- if it's fine bottle it, if not chuck it- so going my that, I'll bottle in a weeks time. Still got those nagging doubts though as I've read up on bottle bombs and gushers, and none of them sound the best thing to have to explain to SWMBO! Especially if I knew the batch had problems. 

John Palmers How to Brew explains the smell being caused by Aceto Bacteria- which can be desired in some beer styles- which doesn't make the infection sound as bad as it could have been, which makes me wonder whether I should be pulling the pin on the whole batch, or riding it out to see what happens.

I was just wondering if anyone had experienced an infection of this type, and bottled anyway, and what problems they encountered after bottling. 

Cheers guys,


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## manticle (19/8/11)

Does it taste like vinegar? Are you smelling the whole batch or just a small hydrometer sample?

Some of the volatile compounds produced during fermentation, when smelled from a whole batch, can be pretty off putting and pretty overpowering.


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## Krew (19/8/11)

Its from the whole batch, and concentrated too as the fridge door kept shut prevents most of the smell escaping. From a hydrometer sample the smell is just noticable, but only because i was looking for it. I know what you mean about the smells we produce when making beer- made my first lager a little while back and the sulphur smell took the lining off the inside of my nose!

As for the taste of the brew, I cant detect any vinegar there, just a slightly sour aftertaste, which isnt harsh or funky enough to make me have to pull the pin. 

Thanks for helping.


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## manticle (19/8/11)

If it's in the hydrometer sample and you detect sour, I'd suggest you have an infection. 

Nonetheless, I'd leave it a few more days and be certain. If it gets worse, I'd chuck it and buy a new fermenter or at the very least, declare Alien VS predator vs King Kong vs the cleaner from black books on its infected arse.

If you enjoy sour/funked beers you could put it away for several months, add various flavours and maybe a brett yeast and age it. That's another option.


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## Krew (19/8/11)

Bugger. 

Looks like the herb garden will be getting pissed soon!


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## manticle (19/8/11)

Yes but don't be too hasty. From experience I know there can be a tendency to spot infection where none exists (and contrariwise to deny one has taken hold when it has).


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## cdbrown (19/8/11)

I'd chill it where it is, rather than racking (another potential source of nasties). Taste it again in a few days while cold and see if the sourness is still there. I've had brews that I detected a hint of infection, but as it upfront and off putting they got consumed. I've had ones where the beer tasted fine but the top of the brew showed signs of infection - chilled and kegged leaving top few cm behind - turned out fine. But if I were bottling I would weigh up the time taken to bottle along with chucking out compared to starting another batch - only after chilling and testing though.


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## Krew (19/8/11)

Thanks for the reply. Thats a good point about racking, thinking about it more, I really dont want to be spreading the infection to another vessel, as well as your point about other potential nasties. 

Im kind of leaning towards chilling for a week and taking another look. I need to wait for some space to appear in a few more bottles anyway- and as its friday night, a few more will appear tonight ;-)

The method you used to transfer the infected beer to a keg seems to be the go, if only I had some bloody kegs. Makes me even more determined to get me a kegerator!!


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## ChrisECarpenter (19/8/11)

If it smells like vinegar, it's a microbial infection producing acetic acid. This can be acetobacta from vinegar flies (amongst many sources).
It won't get better - you're better off to ditch it and sterilse your fermenter.

I would suggest that a highly acidified sulfur solution will be quite effective; do something like 20gms Potassium Metabisulfite, 20gms citric acid, 5 litres of hot water, into fermenter and lots of shaking about.
Then go back to your normal cleaning/santising regime.

Good luck!
Chris


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## Greg.L (19/8/11)

Vinegar smell is caused by too much contact with oxygen - brew left too long after fermentation finishes, with too much headspace and not good seal on the fermenter. Acetobacter needs oxygen, no oxygen no vinegar. Putting every problem down to "infection" is bad practice. You should be trying to see what you did wrong, not blaming random chance.

Greg


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