I’ve had a terrible experience a few times over the course of a few years, and I’m curious of anyone’s insight about what might be happening:
I have beer in kegs (I do a lot of lagers) that tastes fantastic and is absolutely diacetyl free. Come homebrew club meeting day, I slow the beer flow rate with the valve on my Perlick Flow Control tap (which are awesome taps, by the way) and bottle some (right out of the tap) to share with friends. I always sanitize the bottles, but don’t always get the caps. A few hours pass, in the most recent instance, it was about 6 hours. I get to the meeting, I crack open the bottle to share with friends, and it’s got detectable levels of diacetyl, sometimes downright offensive.
I’m certain the beer is free of diacetyl in the keg - First thing I did when I got home was taste the beer. My inital thought was oxidation of alpha acetolactate, but I did a forced VDK test, and still I found no diacetyl in either glass.
I know Pedio can cause diacetyl, and I haven’t totally ruled out a contamination in the bottle, but is it possible that it can happen in 6 hours at relatively low temperatures?
sounds like you’ve done your research, and I’m as puzzled as you are. I’ve never heard of an infection developing within a few hours.
One thought: what temp do you serve at out of your perlicks? Maybe the diacetyl is there the whole time and you and your clubmates are just perceiving it more as the beer warms at the meeting?
Other than that, wish I could be of more help! Good luck-
Unfortunately, I doubt it’s that. I was actually the one who was most offended by it, out of about 12 people. About half of everyone else picked it up, but I’m generally pretty sensitive to the butter.
I serve around 40F or so, and I did my best to keep the bottle around that temp almost the whole time, although it may have gotten as warm as 60F and then back down again before I opened it.
The very act of filling bottles will release much of the dissolved gases, including any low levels of diacetyl that might be in the beer that are typically less than detectable. If these gases fill up in the head space of the bottles, then when you pop the bottles the gases are released all at once. Just a theory.
Are you performing a diacetyl rest during your fermentations at all? If this is something you typically skip, maybe you don’t want to do that anymore. Problem solved, probably. But if you already do one, then I’m at a loss as to how to prevent this.
Also, what are the pitch temps on your lagers (of the yeast and of the wort), especially as compared to your ferment temp? 99% of the time I cold pitch, let the yeast activity warm it up, chug along, then almost always raise the ferment temp at least 5 degrees at the end of fermentation to clean up any diacetyl, though when cold-pitching, I understand that yeast are not producing a lot of diacetyl or alpha acetolactate.
Diacetyl does not occur after fermentation. It was already there but it was not noticeable to you until after bottling. pitch cold and do a d-rest if that does not fix the problem I’d have no clue to what could be causing the problem.
Thanks for your help, everyone. Don’t mean at all to sound like an arrogant dick, but I do lagers very well. I’ve got 15 medals this year already almost entirely for lagers, just as evidence. I always pitch huge, cold, and do tightly controlled fermentations and diacetyl rests. The forced VDK test should have indicated the presence of either AAL or Diacetyl, right?
I’m just baffled because this does happen occasionally but very randomly (luckily never gotten a scoresheet back saying so). I’m just curious of the chemistry or microbiology behind it, and if anyone else ever has the same experience.
The simple and obvious answer is to sanitize the daylights out of everything and fill with a beer gun, like I’d do for a competition. But that’s so much work for a silly club meeting, you know? Seems like one should be able to fill a bottle out of the tap and not worry if the beer is going to be consumed in just a matter of hours.
thats a pretty strange problem I have never had the same issue as you. Its got me stumped as what could be causing this. If you ever figure it out report back so if it ever happens to me I’ll know how to correct.
I’ve had issues with diacetyl forming in the keg a week or two after kegging. The only thing I can think of is I’m somehow introducing oxygen to my beer at racking time, which oxidizes the acetolactate compounds, forming diacetyl. The samples always taste good when I keg, and tastes good for about a week in the keg, then it turns. It’s been in hoppy beers typically.
But, in case not, it’s informative. Basically, fermentation ALWAYS produces diacetyl, but often the end-result will be below the taste/smell threshold (though that, too, varies with each individual). Oxidation, in the absence of active yeast, will result in diacetyl.
thanks alot silentknyght I was always told diacetyl was formed during fermentation. I have been schooled and happy to have learned something new. I sure am going to be even more careful during transfer to keg. brewkid167 thanks for starting this thread lots of good info.
What these guys are saying about introduction of oxygen seems to make sense. What some folks might do is to first squirt a shot of CO2 into each bottle to minimize introduction of oxygen during transfer.
Another thing I just thought of – hoses are not impervious to oxygen or other gases soaking through. If you are bottling from a corny with a good 1 or 2-foot hose on it that’s been soaking in the air from the fridge for several hours, it makes sense that the first beer or two that were sitting in that hose soaking up whatever gases might taste off. I know this from experience – if you spill some root beer extract in your refrigerator where you store your corny, and then pour yourself a beer, that first beer or two might have a root beer flavor from the gases that were soaked into it. Assuming this same sort of thing will occur with oxygen as it does with “root beer gases”, it might pay to throw away the first beer or two before you transfer to bottles.
Things to think about. On the other hand, I don’t keg much so what do I know.
I think the lines are probably too thick for that to happen. If it doesn’t have that flavor when you keg it and tap the keg but develops it later, then it’s probably oxidation during racking or a Pedio infection.
I haven’t confirmed which it is that’s happening to me. Both seem unlikely to me, but it’s happening and it’s very frustrating, so I must figure it out.
I did some more investigating last night and am, unfortunately, still confused. I did a three way comparison - Out of the tap, forced VDK test, and a bottled sample (which was thoroughly sanitized and purged with co2) right out of the tap, allowed to sit overnight in the fridge.
I couldn’t clearly discern diacetyl in any sample but the bottle, where it was quite obvious. The sample from the tap and both samples from the VDK test were not discernible. My wife, who’s actually quite a good taster, verified that I wasn’t crazy. I got to the point where I thought maybe there was a slight note of it in the non-bottle samples, but I was searching for it in every way, so it’s likely I was actually creating my own perception of it in the lowest of thresholds.
I don’t know what to conclude, other than that something about the bottling process is making it more apparent, and it is indeed there, just below flavor thresholds otherwise. Doesn’t make sense, though.
I’ll fill a bottle with my beergun in the near future and see if that makes any difference.
[quote=“brewkid167”]
I don’t know what to conclude, other than that something about the bottling process is making it more apparent, and it is indeed there, just below flavor thresholds otherwise. Doesn’t make sense, though.[/quote]
Well, as stated in the article I linked, earlier, it is ALWAYS there, just likely at 10-30ppb. You could just be one of the lucky (?) individuals whose threshold for diacetyl perception is lower than normal.
[quote=“brewkid167”]Thanks again, everyone, for all of your input.
I did some more investigating last night and am, unfortunately, still confused. I did a three way comparison - Out of the tap, forced VDK test, and a bottled sample (which was thoroughly sanitized and purged with co2) right out of the tap, allowed to sit overnight in the fridge.
I couldn’t clearly discern diacetyl in any sample but the bottle, where it was quite obvious. The sample from the tap and both samples from the VDK test were not discernible. My wife, who’s actually quite a good taster, verified that I wasn’t crazy. I got to the point where I thought maybe there was a slight note of it in the non-bottle samples, but I was searching for it in every way, so it’s likely I was actually creating my own perception of it in the lowest of thresholds.
I don’t know what to conclude, other than that something about the bottling process is making it more apparent, and it is indeed there, just below flavor thresholds otherwise. Doesn’t make sense, though.
I’ll fill a bottle with my beergun in the near future and see if that makes any difference.[/quote]
THere has to be something in your process I would think that is effecting it
