Picnic-tap-sharing cause of infection?

[SpanishCastleAle]

I had a batch of Oatmeal Stout that developed an infection. The early pours and some early BMBF-filled bottles tasted sweet and delicious. The keg is long gone but even now the early bottles taste sweet and delicious. But some later BMBF-filled bottles have less body, less sweetness, and a slight sour twang. There is no objectionable odor (although it is a bit 'off for lack of better word, not sour or smelly though and not vinegary at this level), head retention is fine, doesn't seem over-carbed, etc...just tastes a bit sour and thin. And IIRC, the last few pours from the keg were a bit off too.

My hypothesis is that it was due to picnic tap whoring. At that time I had several kegs ready to drink but not enough picnic taps to go around so I'd just swap a picnic tap from one keg to another if I wanted a pour from a 'tap-less' keg. But I wouldn't sanitize, rinse, or even wipe off the posts. So when I'd remove the QD from a keg there would be that little bit of beer around the post and I'm guessing that allowed the bugs to establish themselves there and then the whole QD assembly got contaminated.

But this would all have to happen under refrigeration (IIRC, hard to retrace everything from 2 months ago). Does this sound like a probable cause? I'm assuming it's an acetic acid bacteria although I don't smell vinegar...possibly because it hasn't gotten bad enough yet.

FWIW, I put a pair of bottles (one of the early bottles and one late bottle) out in the garage and then left another matched-pair in the fridge. I plan to leave them there for at least a week and compare to the refrigerated bottles just to see how much the temp affects it. Other than tasting them I plan to measure the pH but I dunno if the coarse resolution of pH test strips will be sufficient.

 

[SpanishCastleAle]

Interesting find:
The HBD Palexperiment

The HBD Palexperiement Results

While about a quarter of the plates yielded no colonies at all - even after one week - most of the beers showed clear and often dramatic evidence of bacterial contamination. By far, the most common contaminant was Pediococcus damnosus (found in about half of the beers), but we also encountered Lactobacillus, Acetobacter, enteric bacteria, and Bacillus.

Results table

I'm not sure how much causation you can get from such a small sample size...but if you look there do seem to be some 'trends'. For example, look at 'severe contamination' and 'Oxygen' used for aeration (I don't use Oxygen...it was just something I noticed because the columns are close).

 

[SpanishCastleAle]

lol...I forgot I had given some of this away to a friend who doesn't even like Stouts. He drank the other styles I gave him and only had the stouts left so he tried his first one last night...he loved it...couldn't stop raving about how shocked he was that it was so good. I told him if any others taste funny to just dump 'em. He said he had it with popcorn during the game (GO MAGIC!). Maybe the popcorn made it better.

 

[gplutt]

I had the exact same thing happen. I have dumped the picnic taps and cleaned and sanitized the cornys, after replacing ALL the rubber seals. I bottled the last batch of beer I made, with no issues at all.

 

[martymoat]

Same **** happen to me a couple of months ago. Lost about 4 cases of beer, 4 different varieties. I would have the kegs carbonating in the fridge and toss the cobra tap on and when carbonated i would use this to drink some of the beer off the keg for a week or so then the rest i would bottle up and set away for a bit. Well after doing this for 4 different batches and one day hitting up the cellar to grab some beer i had stored away i notice glass all over so i investigate and notice that i have rings around the necks of the bottles and a weird layer forming on the top of the beer. This only got worse and i had to take them all outside and open them cause these bottles where all ready to explode and when opened some of them the force alone was cracking the necks of the bottles off. Finally i ruled it down to me just completely dropping the ball and forgetting to sanitize the picnic tap that had been sitting in the fridge and then using the ghetto bottle filler where i would then bottle. ultimate fail on my part.

 

[Saccharomyces]

My setup is all cobra taps. Each keg gets a dedicated tap. If one comes off, it gets sanitized and the post is sprayed with sanitizer before re-fitting and I immediately draw off a pint so that there is fresh beer in the tap. Between beers the keg gets disassembled cleaned and sanitized... I disassemble the whole tap, rinse it out and soak it in Star San. No problems with infection yet, I can't imagine where one could set in from. I also sanitize the gas posts and QDs when I hook them up using a spray bottle of sanitizer.

 

[SpanishCastleAle]

I have a feeling we'll all be doing something similar to you Sacc.:rockin: