I have a Vienna Lager that I have been lagering at 34F for three weeks. I wanted that to stay at that temp for at least another week and possibly another three weeks for a total of 6 weeks. I brewed an ale this past weekend and I have only my chest freezer, occupied by the Vienna Lager, for a temperature controlled environment so I bumped up the temp to 65F for the ale. If I drop the temp down to 34F after the ale is done, will I see any negative effects on the Vienna Lager having sat at 65F for two weeks? Am I better off to just call the lagering done and bottle it? Any help is appreciated!
in terms of the diactyl rest if you completed fermentation before lagering this likely won’t see much activity. i usually ferment my lagers for 4 weeks.
i assume you are brewing a 5 gallon batch if possible put it in a large styrofoam cooler with some ice packs around it. this will keep the temp down if you change them every day to 65. you may not be able to put the lid on but you could cover it with a blanket.
even here in chicago, in my garage i can put my lagers (only 2gallon) in a cooler with ice packs. i change them every day, twice a day when it gets warmer and my cooler temp stays at 50.
If diacetyl was produced in primary fermentation and a diacetyl rest was not done, the yeast will start to clean the beer if it is raised to 65F and you will see some activity. I’ve seen it with my own two eyes!
Germans don’t do diacetyl rests. If the beer was fermented properly, a diacetyl rest is not always necessary. Also, I wouldn’t think the yeast would become active just to clean up diacetly. That should only happen if fermentation is not complete.
Most likely you’re seeing CO2 coming out of solution, not yeast activity.
It’s possible that the beer didn’t attenuate fully and warming it back up would result in the yeast becoming active again, but I don’t think it’s likely.
Americans, Japanese, Belgians, Indians and Eskimos also don’t do diacetyl rests so long as they pitch the correct amount of yeast and ferment properly. However, with some strains a diacetyl rest is still recommended. See below from the Wyeast website:
“YEAST STRAIN: 2206 | Bavarian Lager
Used by many German breweries to produce rich, full-bodied, malty beers, this strain is a good choice for bocks and dopplebocks. A thorough diacetyl rest is recommended after fermentation is complete.”
All I’m saying is if there is some, and the beer is raised to diacetyl temps, then there will be activity in the airlock. This just happended to me recently and the beer was feremented out. Could it have been degassing, I guess, but it lasted a few days.
But if the beer is fermented out, how could there be continued fermentation activity? And FWIW, I use 2206 frequently and I don’t remember ever having it throw diacetyl.
That I cannot answer. I figured it was the yeast cleaning up. It was at 1.013 and the top end of the attenuation for the strain. Maybe it fermented out further? I’ll take another gravity reading today as I’m kegging it. I hear ya on the 2206 as well. The sample tasted great.
unless the beer was carbed prior to lagering there should not really be much co2 coming out of solution. a little because of the temp change and equilizing the partial pressures but i would not expect much. and fwiw, i don’t even see much air lock activity to begin with when i lager. i can do a 2 gallon batch in a 2 gallon bucket (there is still about 1/2 inch of airspace. and get no overflow, activity etc.0
SO, I ended up doing a D-Rest for 4 days per the Wyeast recommendation for 2206 and the activity picked up dramatically. At the start of the D-Rest it was at 1.013 and I kegged it last night at 1.012. So it dropped a point but that does not seem like a lot for 4 days of activity. So what was the activity then? Tom mentioned CO2 release by diacetyl reduction not being part of the pathway. So what was happening? As previously stated I thought it was due to the yeast cleaning up the beer but now I’m thoroughly confused… ???
Sorry to hijack the thread, but it still seems to fit with the OP and subsequent replies.
I believe Wyeast and Whitelabs put these kinds of statements in their descriptions because their expecting people to under pitch and stress the yeast. When the yeast become stressed, they will throw off more diacetyl, amongst other compounds. By letting it warm up that can help the yeast clean up it’s own mess.
As long as you’re pitching the right amount of yeast, you may not need a diacetyl rest.
Since you’re moving from lager fermentation temps to pretty much room temp, there would be much more CO2 released than what you would see with ales. Colder liquids absorb CO2 much better than warmer liquids. I’m betting this is what you saw.