Acetic culture

[brownni5]

I've got a small culture of Jester King dregs, maybe 150 ml, that I opened up to feed in preparation for an experimental brew. It's gone acetic, really vinegary. This is a dumper, no? By that, I mean I can expect that acetic character to persist, right?

 

[Funky Frank]

No. That acetic character will only present if the Brett is in contact with o2. I had a post about a Flanders red that was too acetic a while back. I dumped new wort on the cake and fixed my o2 leaking issue and it made a delicious sour ipa type thing.

 

[Gnomebrewer]

No. That acetic character will only present if the Brett is in contact with o2. I had a post about a Flanders red that was too acetic a while back. I dumped new wort on the cake and fixed my o2 leaking issue and it made a delicious sour ipa type thing.

I've also had brett starters that have become overwhelmingly acetone-y from too much O2 (with more O2, acetic acid can be turned in to acetone). Used in a brett saison with O2 minimised, the beer was great. I read lots of previous threads about how cultures with acetone should be dumped as they'll keep making acetone - it turns out to not be true.

 

[sweetcell]

I've got a small culture of Jester King dregs, maybe 150 ml, that I opened up to feed in preparation for an experimental brew. It's gone acetic, really vinegary. This is a dumper, no? By that, I mean I can expect that acetic character to persist, right?

it depends on the reason why it went acetic. if you exposed the started to a lot of O2, then the brett may have created the acetic acid. in this case, 150 ml would be unlikely to be perceptible in a full 5+ gallon batch, so i would feel comfortable using it. however, if acetobacter is the reason why it tastes like vinegar, then i wouldn't use it - you have an large, active population of aceto and i wouldn't chance adding that to a batch. and if you're not sure which of these two reasons explain the acetic acid, then it comes down to: do you feel lucky, punk? personally, i wouldn't chance it but i'm kinda risk-averse when it comes to rolling the dice on something that will be aging for a year. YMMV.

No. That acetic character will only present if the Brett is in contact with o2. I had a post about a Flanders red that was too acetic a while back. I dumped new wort on the cake and fixed my o2 leaking issue and it made a delicious sour ipa type thing.

unless the reason for the acetic acid isn't brett + O2, but acetobacter.

I read lots of previous threads about how cultures with acetone should be dumped as they'll keep making acetone - it turns out to not be true.

all blanket statements like that should be viewed as suspicious...

it depends on the mechanism by which acetone was created, and whether those conditions will be recreated in the new batch. in your case, you got acetone due to too much O2 exposure (a very common way of creating acetone). you fixed the O2 issue (i.e. changed the conditions) and the acetone didn't reappear. but if someone's culture starts throwing acetone under "normal" conditions, and they intend to reuse that culture under the same conditions, then one shouldn't be surprised to experience acetone again. the risk here is that if you have an acetone-generating culture, are you 100% certain that you've ID'ed the right fix? again, it comes down to your risk tolerance...

 

[RPh_Guy]

it depends on the reason why it went acetic.

Reducing/eliminating excessive oxygen exposure prevents acetic acid production regardless of which microbes are in the culture.

it depends on the mechanism by which acetone was created

The same goes for ethyl acetate. Preventing excessive oxygen exposure prevents excessive ethyl acetate production. If you're aware of a culture that produces offensive levels of ethyl acetate under anaerobic conditions, I'd be interested to hear about it.

 

[sweetcell]

Reducing/eliminating excessive oxygen exposure prevents acetic acid production regardless of which microbes are in the culture.

correct, and i didn't say otherwise. my point being that if the reason is brett, you have more leeway - brett needs a lot of O2 to make acetic acid. acetobacter, on the other hand, is a more efficient producer of acetic - requires less O2.

The same goes for ethyl acetate. Preventing excessive oxygen exposure prevents excessive ethyl acetate production. If you're aware of a culture that produces offensive levels of ethyl acetate under anaerobic conditions, I'd be interested to hear about it.

preventing excessive oxygen exposure prevents excessive ethyl acetate production in the majority, but not all, cases. ethyl acetate can also be the result of of a stressed yeast, or too-high ]fermentation temperature. Hansenula and Pichia are "wild yeasts" that can product EA in high quantities but O2 is required.

 

[Funky Frank]

Taking this back to the original post, acetic acid is OFTEN (not always) due to good bugs just being exposed to bad levels of O2. That said, others are right that there is a little gamble with using a starter with a high acetic acid content. In a perfect world your starter would probably taste and smell as awesome as the beer you’re hoping to create.

I have a lot of sours going at any given time and I have some uses for malt vinegar (if it would go that way) so I’d use that starter. If it were my first sour or I only had room for limited sour production, I might not use it. Then again, maybe I would...lol.

 

[RPh_Guy]

ethyl acetate can also be the result of of a stressed yeast, or too-high ]fermentation temperature.

My point stands that the population of microbes has no bearing on future production of excessive ethyl acetate if oxygen exposure isn't excessive. There's not one microbe that gets in there and you're doomed to getting nail polish flavor.