Stuck Fermentation in High Gravity Beer

[DocBrown]

It appears that I do, in fact, have a stuck fermentation. I brewed a 5 gallon batch of AHS' Cannonball Stout (extract recipe) back on March 28. I measured the OG at 1.115. However, I realized later that my reading was probably inaccurate. I took my sample from the spigot at the bottom of my ale pail (I know, I'll get a turkey baster before my next batch!) after doing a 2.5 gallon boil and pouring additional water on top of the wort in the fermenter. I don't think I mixed it very well, as the recipe sheet from AHS predicts an OG of 1.100, and the only place I deviated from their recipe was in the addition of the BrewVint yeast fuel (in hopes of preventing what I have now!) and a whirfloc tablet to the boil.

In any case, I knew up front that this would take quite a while to finish. I had very active fermentation for a while and got a decent amount of foam coming through the blow-off tube. I didn't see any obvious signs of continued fermentation after a week, but I've read enough of Revy's cut-and-pastes to know that the level of airlock activity doesn't tell you much at all. After two weeks my SG was down to 1.040. Unfortunately, it's barely moved from that point. At 3 weeks it had only dropped to 1.039. I sanitized my brewing spoon and gently stirred the wort at least to the point where I saw bits of the trub floating back up to the surface. However, it's been another full week (the wort has been in the primary for a full month now) and the SG is still 1.038. The wort sample does have a sweet syrupy kind of taste indicative (at least in my very inexperienced judgment) of plenty of remaining sugars.

I did check and verified that my hydrometer is accurate. At worst it's off by about 0.002 depending on how pure my tap water is. I originally pitched two vials of White Labs WLP007. My fermentation temperatures have not been especially stable as north Alabama has gone from 85F down to snow and back over the last month, and my brewery closet is not especially well insulated and has no room for a swamp cooler setup. However, the temperature of the air around the fermenter has ranged from about 65F to 72F.

So I'm wondering what my next step should be. A number of threads I've read in here have implied that additional yeast may not really help since there should be plenty of yeast cells remaining. However, with the wort already at 8+% ABV, should I consider pitching some yeast with high alcohol tolerance to finish this off? Alternatively, is there a good yeast enzyme I can add to get things going again? Would 1oz or so of corn sugar give the yeast something a bit easier to work with to get going again?

Thanks for the help.
JB

 

[COLObrewer]

I'm not familiar with your yeast (and too lazy to search) but personally i would stir the $%#@ out of it before I try more yeast, or more fermentables. Your yeast is drunk on it's own alcohol, it went to sleep, wake it up! Don't play with it, get all that trub to the top. That is if it is tollerant of 8+%?

 

[llazy_llama]

I originally pitched two vials of White Labs WLP007. My fermentation temperatures have not been especially stable as north Alabama has gone from 85F down to snow and back over the last month, and my brewery closet is not especially well insulated and has no room for a swamp cooler setup. However, the temperature of the air around the fermenter has ranged from about 65F to 72F.

This paragraph, in my mind, is very telling. Most experienced brewers (no offense, I made worse mistakes myself when I was starting off) would have used 1 vial of liquid yeast to make a HUGE starter for a beer with an OG of 1.1 or higher. According to Mr Malty, a beer that big would require a starter (using only one step, you'd need 2 vials of WL yeast) ending up with about 353 billion cells of yeast. An average vial of WL yeast contains 60-100 billion viable cells. That means that you likely under-pitched by a huge margin.

That being said, I think it should still ferment out completely, or at least I hope it will. Give it more time (as in 2 more months in primary) then check the SG again. The ambient temps varying 7 degrees shouldn't make a big difference, so don't sweat that. Just give it time, time, and more time. You'll probably want to use a secondary with this brew as well, but give it a month or two longer in primary. This is a huge beer, and you really need to give your yeast time to finish eating their fill. It's going to take a while.

Hope that helped.

 

[david_42]

WLP007 can, in theory, handle 10%. However, pitching the vials directly into a 1.115 wort wasn't a good move. You could try a couple packets of S-04 or Nottingham, but re-hydrate them properly before pitching.

In the future, make a smaller beer before a big one and pitch the big beer on the cake. It's like making a 5 gallon starter.

 

[DocBrown]

First, I want to thank everyone for the comments. I agree with Llama that I should have done a starter, but this was an AHS kit, so I just decided to be lazy and go with what they recommended. But it's now been 2 months since I put this beer in the fermenter, and the SG is still 1.036. In the last month and a half the gravity has only dropped by 0.004. I'm thinking it would be worth it to try pitching more yeast.

It looks like the S-04 yeast is equivalent to what I currently have in there, so it shouldn't change the taste too much. Would I be better off trying to do a starter at this point to acclimate the yeast a bit before they get dumped in an 8+% ABV wort? Can someone give me some tips on what type of starter I should use in my situation?

 

[Brandon O]

DUDE!!!!

I didn't read anywhere in here that you oxygenated the wort.

Did you oxygenate the wort before pitching?

Heres what you do now.

Take .5 gallons of water and use .5 lbs of LME or DME. Pitch some safale-04 onto that and let it get going nice and good. Say 36-48 hours. Then shake the starter really good to oxygenate the starter a little bit. If you want to tackle that stuck fermentation you are gonna need some O2 but you don't want to oxygenate the wort, oxygenating the starting should do fine. Pour it into the beer and let it do it's thing. It would be a good idea to agitate the carboy pretty good after pitching.

In the future for any beer above 5% you gotta make a starter.

Here's my advice for starters. I make mine while the grains are mashing or during the boil because let's face it. I'll never remember, or feel like making a starter before the brew day.

So I take a half gallon of water and .5 - 1 lb of dme and bring to a boil and then cut the heat. Then I let it cool down and pour it into a 1 gallon glass jug I have and put a bung and airlock on it.. I put that in the fermenter to get it down to my fermenter temp of 68 degrees. Then I go back to my brew and finishing mashing or boiling.

Once I'm done brewing, I cool down the wort and then oxygenate it and put it in the carboy and then in the fermenter, then I put an airlock and a bung on that. I always make sure to swirl my starter around as much as possible or every time I remember to keep the yeast in suspension. I don't own a stir plate yet and this works pretty well. So the next day the yeast has been going a good 12-18 hours and i let it go another 12 or so, swirling around the starter when I remember to do so.

Then I just dump the whole the whole starter in the wort and it takes off and finishes nicely every time.

I once thought i needed to have a starter read to pitch when the beer was cool, then I realized. THAT BEER ISN'T GOING ANYWHERE!!!! I can make a starter a few days later if I like.

Another good idea is, save like .25 gallons of your wort and add another .25 gallons of water. Use that as your starter!!!! its the same thing you are pitching into, just less strong so the flavor profile will be the same and the yeast will be familiar with the brew already.

Using 2 packs of yeast won't get you what you need, a simple starter will.

Those yeast packets say they are good enough to pitch directly, but let's be real here. A starter is going to make your beer SO MUCH BETTER!!!!. A little starter can do the work of 4 packets of yeast, and those liquid vials are EXPENSIVE!!!!

 

[DocBrown]

Time for an update. It's now been nearly 4 months since I originally brewed this beer, and it's been sitting in the same Ale Pail the entire time. To answer Brandon's question about oxygenating, I did pour the wort into the fermenter through a strainer and shook it up a good bit to get a decent amount of air in the wort, and it did ferment pretty violently early on (it was a good thing I read about blow-off tubes on here!). So I followed Brandon's advice and made a 2qt starter (2qt water + 6oz light DME) with a packet of S-04 yeast. I let that sit for 24 hours (shaking every so often) and then poured it into my fermenter. That was on June 14, and the SG just prior to adding it was 1.036. I checked the gravity on July 6, and it had dropped to 1.032. Today (July 18), it was down to 1.031.

I have a couple questions. First, now what? This has been sitting in the fermenter for nearly 4 months and still has an awfully high gravity. The AHS recipe says it should get down to 1.017. At this point I'd be thrilled to see it below 1.025! Is there anything else I can do to it to get things moving again? How much longer should I let it sit? Would it be worth stirring it up to get all the yeast back in suspension then transfer it to a carboy, or are there really any problems with an imperial stout sitting in an ale pail for several months? Also, my wife posed an interesting question. If the fermentation appears to have completely stopped anyway, do I really have a significant risk of bottle bombs if I go ahead and bottle now?

 

[beersydoesit]

Okay, this is a little off, but it has worked for me.
You could try revitalizing your yeast cake.
It is done by;
Racking the beer into a sanitary secondary.
Maintain sanitation on the yeast cake.
Make the wort for a starter with DME, just like MRMalty says, but add no yeast.
Pour the starter onto the yeast cake.
Aerate like crazy and let it work 12 to 24 hours.
Rack the beer back onto the yeast cake.

I had a stuck Belgian and it got things going again.

 

[DocBrown]

I had an idea along similar lines today. I was thinking about starting a new beer - probably the AHS Dry Stout (Austin Homebrew Supply), though probably with the WLP007 yeast instead of WLP004. I could let that finish fermenting (probably about 10 days) then rack it to a secondary and leave the yeast cake behind and transfer the Cannonball stout on top of it. Would that have a reasonable chance of working? It would get some fresher yeast on the job just after finishing up an easier beer.

As an additional question, by yeast cake I'm assuming that means all the sediment in the bottom of the fermenter, including the remaining hop residue and whatever proteins the yeast produce, yes?

 

[jp4669]

My gut feeling is that the yeast cake won't work any better than the other yeast you tried. If you're readings were correct, you're at about 11% alcohol, and even if they were a little off, you're probably still close to 10%, and I'm betting that there's just going to be too much alcohol already there to give a normal beer yeast a fighting chance. I'd either aerate and try a champagne yeast, or just drink it as-is. I bet it would be tasty now, and it just might fuel rockets with champagne yeast, if that's your goal.

 

[iamschroedingerscat]

Hey, I have a similar problem. I brewed a high gravity beer of my own design. OG is 1.097. I didn't make a starter this time, but i pitched 1.5 packets of champagne yeast. I had very active fermentation for the first few days, but the airlock activity has stopped. Gravity has been at 1.034 for a few days. My math says that it has a 62% attenuation. What are your opinions on switching to secondary? Before anyone asks, i aerated quite a bit. I poured wort between to sanitized buckets several times. I wanted to have the Gravity drop below 1.020, but is that going to happen? Any opinions or suggestions?

 

[HoopyFrood]

I also am suffering from a stuck fermentation on an Imperial Stout (O.G. 1.114). It stuck at 1.052 after a few days of very vigorous activity. I left it for two weeks in the primary and transferred it to the secondary. It's been in the secondary for a few weeks with no gravity changes and I have found no successful tricks un-sticking the fermentation.

Firstly I way under-pitched (used WLP099) and I way under-aerated - so I will not repeat those mistakes in the future. If my last trick doesn't work I will resort to cultivating a fresh batch of WLP099 successively in starters to get a 2-3Q size (to achieve a cell count of 200-300 billion), decant, re-pitch and cross my fingers. If that doesn't work nothing will.

Most authors I've read say transferring to secondary too soon (prior to two weeks) can lead to stuck fermentations if conditions were less-than-ideal. It sounds like Noonan is the only one who claims that transferring to to secondary too late can result in stuck fermentations. Can anyone clarify this? What does Noonan mean by "too late" and what possible mechanism could contribute to stuck fermentation when you delay pulling beer off the primary yeast cake?

John Palmer has written (esp. in "How to Brew") that introducing oxygen when going from primary to secondary can result in stalling fermentation. He has asserted this on several occasions, but I have not yet found (in his writing) a reason why. I will asked him (via e-mail @ howtobrew.com) and will forward any response I have to this thread. But perhaps someone else out there knows how introduction O2 can stall post-primary fermentation?

I certainly introduced a very minor amount of O2 when going from primary to secondary, but nothing I would consider "significant" let alone "disastrous".

Thoughts?