Hi, all. I’m brewing my first lager, a Munich Dunkel, and I think I may have kegged too soon. I started with a 4L yeast starter and had it in a primary carboy at around 48F for 2.5 weeks. OG was 1.054 (right on target). Krausen started to fall so I jacked the temperature up to ~65 for a couple days for a diacetyl rest. I then transferred it to a keg I was going to use as a secondary/lager and took a reading. My FG was 1.029, way too high (needed to get to about 1.015).
At this point I’m thinking I’ll leave it in the keg at the high end of the yeast’s preferred temperature range (58F) for a week or two before dropping the temperature down to lagering temp. Is this a futile effort considering the yeast cake is now gone? Could keeping it warmer in the keg for another couple weeks and lagering for a couple months help it get to FG?
If my plan might work and fermentation continue, should I release pressure from the keg’s pressure relief valve periodically?
Yes, the beer probably needed another week in the fermenter. Consider pitching more lager yeast (perhaps Saflager W34/70 dry yeast) and leave it at 65°F. You can use a hose quick-connected to the gas post as a blowoff hose (with the other end in a bucket of sanitizer) so you don’t have to keep manually venting.
Dang, it only finished at 1.029? Yikes…that beer will be ridiculously sweet. My guess is you way under aerated. A 4L starter should’ve been plenty, at least to not under attenuate to that degree.
Yeah, I’d maybe try what ajk suggested. Pitch a pack of 34/70 into the keg, rig a blow off with a piece of hose attached to a gray gas disconnect, run it into a jar of sanitizer and let it go at 65 for a bit. You’re not gonna want to drink that beer.
Last resort, you could get some Amylase Enzyme, pitch a teaspoon of that, let it go for a week or 2, then rack to a new keg.
I measured with a refractometer but had been worried about under-aeration. I managed to cool the wort quickly with an immersion chiller and large stirplate (3" stirbar) to room temperature and then stuck it in my keezer overnight to drop it to pitching temp. I figured the stirplate action had aerated the wort pretty well so the next day when I pitched the yeast, I didn’t bother to try and aerate it anymore. I got good bubbles and krausen within 36 hours so I figured that had been fine but maybe I should have aerated with pure oxygen?
It sounds like you guys don’t think the remaining yeast will be enough to continue fermentation in my keg so I should repitch. I’ve never fermented in a keg before. Do I really need to bother with a blow-off tube? Isn’t the keg strong enough to withstand extra pressure if I manually vent a little every day (which I don’t mind doing)?
Did you make the correction to your refractometer reading?
After fermentation a refractometer will read high.
Check out seanterrill.com for a refractometer FG calculator
Say whaaaaaaat? Okay that is exciting news! I guess I need to learn how to use my refractometer correctly. I had no idea I needed to adjust the FG reading for alcohol! You guys are the best - thanks for the help.
also taste those samples. I’m guessing if you tasted it you would have immediatly known that there was a measurement error. to Paraphrase Denny, we taste beer not numbers.
So this will sound funny but I’m not much of a lager guy. I only went with a lager this time because I just built this keezer and wanted to try it out. So I DID taste it and it didn’t taste wonderful. I wasn’t sure, though, if that was because it was sweet (I really couldn’t tell) or because I just don’t like lagers much and that’s just what an unripe lager tastes like. It didn’t taste spoiled or anything, just kinda bla.