Slow Lager Fermentation

[jar1087]

I brewed a Munich Dunkel on 3/26 with an OG of 1.058 SG and am concerned about the fermentation. I originally pitched with a half gallon starter made with WLP830 German Lager Yeast and then used the drauflassen procedure from braukaiser.com to hopefully improve my yeast health, as I've had slow first generation fermentations with this yeast before. Unforntunately, the yeast seemed to never really awaken and after three days of no activity (confirmed by hydrometer readings), I grew up a second half gallon starter and made sure that it was active, before pitching it into the fermenter. It has now been 15 days since I pitched the second starter and there has been some activity, but the fermentation is still very slow. The gravity is only down to 1.034 SG and is slowing down further, likely headed for a stuck fermentation (FFT was 1.013). I have already raised the temperature about as high as I am comfortable for a lager (55F), so now I'm looking for ways to encourage the fermentation.

My thoughts are either to aerate for maybe 10 minutes and add some yeast energizer and hope for yeast growth or to grow up another starter and repitch (again) in order to bulk up the active yeast population. I think that the aeration would be safe, as the beer still has another 20 points or so to go, and the yeast should still have time to clean up the oxygen, but am not sure if it would really encourage them to grow much more. The downside of the repitching method is that it will take longer and with the several steps necessary to grow the yeast up to pitching volume, would introduce several opportunities for contamination.

So which method do you think would be better?

 

[boo boo]

I don't think I would aerate at this point.
Perhaps you could pitch a few packs of rehydrated good dry lager yeast that don't really need aeration.

 

[BryceL]

I'm in a similar situation (using WLP820) for an Oktoberfest. My fermentation started off strong, which I was happy with, and it has been bubbling fairly constantly since then. I'm on day 15 right now and its still going...seems to be slow and steady. I checked the gravity two days ago and it was at 1.036 (OG 1.065, estimated FG 1.018). I have had it at 50 degrees and went ahead and bumped it up to 65 for a diacetyl rest. I'm hoping that it finishes okay. I'm planing on taking another reading tomorrow afternoon to see how it's doing.

 

[mlyday]

I am also doing a 820 Oktoberfest and never really got a sup active ferment. I did pitch a really big starter from a stirplate, and have had a pretty steady, but not strong ferment. At one week I was down from 1.053 to 1.028 and So I warmed from 53 to about 60-62, for a D-Rest. I havent taken a reading since I started the D-rest, but the bubble are really slowing down. One thing I did this time was to pick the buck up every day and twist it back and forth by the handle. Not shaking it just a couple of twists to maybe just disturb the yeast.

 

[jar1087]

So I ended up deciding on the aeration + energizer method, since it's a) easier, b) lower risk of contamination, and c) hopefully faster. Airlock activity seems to have picked up already, so in a few days I'll take another reading. I'm hoping to get down to about 1.024 before doing a d-rest and cold crashing. I'll report back when I know more.

 

[BryceL]

Well, I brought my Oktoberfest up to 65 degrees for the diacetly rest. I've had it there for two days and just took a hydro reading/taste test. I was very happy to see that my gravity has now dropped to 1.022 so its getting very close to my estimated FG...and it's still bubbling away in the fermenter. It's amazing how much the taste has cleaned up. 4 days ago it was super buttery, almost undrinkable. Today it actually tastes quite good! I'm going to leave it for one more day and then start to drop the temp back down.

 

[jar1087]

That's great! Keep us posted.

 

[jar1087]

Ok, well it has now been four days since I aerated and added energizer and the fermentation has continued to slow down (gravity went from 1.034 to 1.030); so fail on the aeration method. I decided to switch off my fermentation fridge and let it start to warm for the diacetyl rest, so hopefully slowly allowing it to warm should get me rest of the way. I was aiming for an FG of 1.014, but if I can get down to 1.016 or so, I'll be happy. I'll report back in a few.

 

[BryceL]

Hopefully increasing the temp wakes those guys up, with two starters you should have enough in there. Good luck. I'm dropping my temp back down now. I'm going to give it another week in primary and then rack to my keg for lagering. I'll check the gravity when I rack and let you know how it ended up.

 

[jar1087]

I'm happy to report that 4 days of diacetyl rest at ~65F brought my gravity down to 1.015, which I'm quite happy with. It's now kraeusened and bottled as of two days ago and I'm slowly bringing it down to lagering temperatures. I'll let you know how it is in a few weeks.

Also, I definitely learned something through this process. I previously was under the impression that the diacetyl rest should be performed when the beer only had a few points (say 2-4) left to go, but further reading showed me that it should be done with as much as 30%-40% of the fermentation left to go.

 

[tesilential]

I also thought the diacetyl rest was performed after primary fermentation was done! I'm brewing my first lagers soon so that's very good to know. I would think the lager yeast would make lots of esters at those temps, especially with so much sugar left to eat.

 

[BryceL]

Glad to hear that you got that FG down, I'm sure it will turn out tasty! I'm going to have a strict no-touch rule on my Oktoberfest until September 1st...that's going to be tough. I'll get one more gravity/taste test in on Sunday when I rack to my keg. Most of what I have read says that when about 75% of the fermentation is complete you can do the diacetyl rest. Most of the esters are created from high early temps.

Tesilential--just try to pitch your yeast as low as possible and you can avoid needing the diacetyl rest at all. I wasn't able to get my down as low as I wanted before pitching (about 60) and ended up with A LOT! It's amazing what the rest can do for it though!

 

[tesilential]

Tesilential--just try to pitch your yeast as low as possible and you can avoid needing the diacetyl rest at all. I wasn't able to get my down as low as I wanted before pitching (about 60) and ended up with A LOT! It's amazing what the rest can do for it though!

I can pitch as low as I need, since I cool overnight. I'm worried that it'll stall out like then others in this thread.

 

[BryceL]

As long as you pitch enough yeast, you should be fine...mine ended up being a 4L starter. MrMalty always works good for me. Just don't be surprised on the long lag time...it will start though. I know there are several ways of fermenting lagers that work well, so whatever you are comfortable with. I plan to pitch my next lager around 50.

 

[jar1087]

Yeah, I didn't get much in the way of esters based on my last taste/gravity reading. I pitched around 50F and may pitch even lower next time so that I can ramp it up slowly throughout the fermentation. Kai's site (braukaiser.com) says that lagers in Germany are sometimes pitched as low as 41F and a number of sources agree that the temperature control to avoid off flavors is most critical during the first 24 hours or so (maybe 48-72 for a lager) while the yeast are in their growth phase. I'm planning to brew an amber lager this weekend and now that I have plenty of yeast slurry from this batch, I figure the next fermentation should go much better.

@BryceL - Good luck not touching it until September, but I'm sure it'll be great if you can hold off. I'll probably try a bottle next weekend to see how mine is progressing and then a bottle a week until it's ready.

 

[jar1087]

The dunkel is now down to lagering temps (40F in my fridge) and I opened a bottle today to test the carbonation, which seems to be going great. Can't wait to taste it when it's done lagering.

Also, I brewed my amber lager and pitched the yeast cake from the dunkel into it; 24 hours in and I'm seeing fermentation activity :rockin: Gott sei Dank!

 

[bernerbrau]

This is helpful. I have a pilsner at 48F and it's had a krausen for 22 days now. I didn't realize I could bring it up for a diacetyl rest to finish it.

 

[BryceL]

The dunkel is now down to lagering temps (40F in my fridge) and I opened a bottle today to test the carbonation, which seems to be going great. Can't wait to taste it when it's done lagering.

Also, I brewed my amber lager and pitched the yeast cake from the dunkel into it; 24 hours in and I'm seeing fermentation activity :rockin: Gott sei Dank!

Nice job reusing the yeast cake. I haven't done that yet...tossed my Oktoberfest yeast since I don't have room for another lager right now. I kegged mine on Sunday and it's now lagering. FG hit 1.020, right within my expected range...and it was tasting gooood! I also got going on an Amber Ale on Sunday so hopefully that will keep my mind off my Oktoberfest for a while.

@ bernerbrau - Yeah, the rest will definitely help finish it off. Good luck with that one!

 

[Bamsdealer]

Bumping this as I'm glad to see others had slow starts from lager yeast. My pilsner is only two days in and I knew it would be slower. I was excited to see airlock activity after 18 hours, but it has yet to pick up. 30 seconds between bubbles... hasn't picked up at all since I noticed the original airlock activity.

I'm sure I underpitched with a 2 liter starter... especially since the starter never really developed a krausen. It was still somewhat sweet when I pitched, but there did seem to be more yeast than I started with. I guess this is one of those brews where I just have to wait longer and let the yeast slowly do their work.

 

[CDGoin]

Another bump.. because Im having issues with an Oktoberfest that started out with the Brewers Best kit and 2 lbs of honey and the dry yeast pack that it came with. BTW have done this twice before and love the end result. This time NOTHING.. no fermentation nothing. Added a vial of WLP820 (NO exact sachet of the dry yeast that came in the kit at the LHBS)

Got temps up to 64 (Directions on WLP820 say to go to 70 UNTIL fermentation starts in 5-15 hours.. I can't get garage that warm).. and its going on 15 hours with no sign of much action at all.

How have you guys aerated safely..? As I may have to do that. Its the only thing can think of that would have two yeast batchs not ferment. That or some yeast energizers.. heard those can cause off flavors though.

 

[BryceL]

I aerate with pure oxygen and a diffusion stone, but before I got that, I would just shake my carboy for several minutes. Did you aerate initially? I'd say give it a bit longer (at least another 12 hours), maybe give it a gentle swirl. You may be okay to aerate if you are sure fermentation hasn't started, but I know I have heard that it is not advised to aerate after fermentation has started. I haven't had this issue yet, so I can't speak from personal experience. On a side note, I always pitch my lagers low and let them raise to fermentation temperature so I wouldn't worry that you didn't get your temperature up to 70.

 

[Yooper]

Another bump.. because Im having issues with an Oktoberfest that started out with the Brewers Best kit and 2 lbs of honey and the dry yeast pack that it came with. BTW have done this twice before and love the end result. This time NOTHING.. no fermentation nothing. Added a vial of WLP820 (NO exact sachet of the dry yeast that came in the kit at the LHBS)

Got temps up to 64 (Directions on WLP820 say to go to 70 UNTIL fermentation starts in 5-15 hours.. I can't get garage that warm).. and its going on 15 hours with no sign of much action at all.

How have you guys aerated safely..? As I may have to do that. Its the only thing can think of that would have two yeast batchs not ferment. That or some yeast energizers.. heard those can cause off flavors though.

One package of yeast is too little, especially if you have a fairly high OG. Four packages would be more likely to be the correct pitching rate.

 

[CDGoin]

Thanks.. It finally got started with the vial of liquid yeast on top of the dry.. fermentation is slow and krausen is more a light foam and less krausen.. but it is fermenting now. Can I assume now that it is going.. it will create the yeast it needs..? OR should I pitch another vial?

 

[CDGoin]

one more thing.. i started with sachet of dry lager yeast from brewers best kit, the second time I pitched the White Labs liquid oktoberfest yeast.. Will that throw things off..? Will the yeasts fight or one kill the other.. Etc.. Just curios is all since its not like I can do anything now anyway.

 

[Yooper]

one more thing.. i started with sachet of dry lager yeast from brewers best kit, the second time I pitched the White Labs liquid oktoberfest yeast.. Will that throw things off..? Will the yeasts fight or one kill the other.. Etc.. Just curios is all since its not like I can do anything now anyway.

One strain will probably take over, but I'm not sure of the results or which strain.

Glad to hear it's going now.