Second all-grain brew tastes like vinegar

[atothekaj]

I'm new to brewing but well-read on the subject. On my second try I brewed 6 gallons of vinegar. Now, I believe the culprit is acetaldehyde (it tastes like apple-cider vinegar).

I took a dram from the fermentor two weeks after the primary fermentation and noticed the offending flavor right away. The "beer" has been in it's primary fermentor for a total of five weeks now and there has been no change to the severity of the flavor (it hasn't gotten worse or better).

Since acetaldehyde is an intermediate of the metabolizing of ethanol via yeast i assume there's a high abv brew here that, for whatever reason, has stopped short of it's potential.

I'm looking for advice (other than "pour it out"). I'm thinking that re-pitching yeast (high alcohol tolerant) could clean it up. If that could work: should I also add some yeast nutrient?

Anyone out there with experience in successfully cleaning up acetaldehyde? Since I'm new to brewing I'm not just trying to save a brew I'm also learning so of you vets have anything useful to share on the subject I'm very appreciative.

 

[eastoak]

i would dump it but if you want to try to save it you can add some sugar to the fermentor and the yeast will reduce it to ethanol. how much sugar? i don't know. on second thought you could also make a half gallon of wort using extract and not lose body the way you would with sugar. you didn't post much info about the beer but this is what i would do if i was inclined but as i said, i'm a dumper of beer gone sideways.

 

[masonsjax]

Vinegar is acetic acid produced mainly by acetobacter. If it is indeed a vinegar flavor, you have an infection which can't be reversed.

 

[eastoak]

masonsjax is correct, another possibility is an infection. that worst case was one i didn't consider at first but if it's a strong flavor it could be a dumper for sure. or you could use it as vinegar i suppose.

 

[RM-MN]

Try raising the temperature of the fermenter. I think your yeast are struggling to break down the acetaldehyde. Vinegar in the primary would not be likely as acetobacter that causes it is aerobic and unless you tried to get rid of the CO2 it can't get started.

Acetaldehyde can be improved, vinegar always gets worse. Since you have no change in the past 3 weeks I don't believe you have acetobacter.

 

[atothekaj]

Thanks for the replies.

I considered that it could be an acetobacter or lacto infection. However, the off-flavor was almost immediate which is uncharacteristic of lactobacillus. Although, I've read that acetobacter can come on strong and fast. Also the offending flavor is vinegar-like (aceto character) but also sour like green apples (acetaldehyde character). I suppose they aren't mutually exclusive.

It hasn't been exposed to air (and is covered in a layer of CO2 in the fermenter). Also, it doesn't taste foul in any other way. In fact, as I'm a big fan of Lambic and Sour beers, I wouldn't mind a bit of sourness.

I just thought I might try something to save it before moving on to the next batch.

Since I'm a novice I'm sure that I've made some mistakes with this brew. Trying to diagnose this problem has encouraged me to read up on sanitation and infections which will hopefully make my next brew more successful.