Stuck Fermentation on Really Big Imperial Stout

[flow415]

Hi All,

I'm trying to brew a REALLY big Imperial Stout and my fermentation is stuck. I used MoreBeer's Imperial Stout recipe as a base and added more ingredients. See below:
15 lbs 2-row
1 lb Carapils
1 lb Crystal 40
8 oz Roasted Barley
6 oz Black Patent
6 oz Chocolate Malt
2 lbs Oats
1 lb Crystal 120L
1 lb Crystal 60L
1 lb Cane Sugar
10 lbs LME

Yes, I know that's A LOT of ingredients and I ended up with an OG of 1.138 and you could tell it was a bit thick before I began fermentation. I used a S-04 yeast starter (with yeast nutrients) from a previous batch of stout which brought the gravity down to 1.076 after about 4 weeks (took a while). Then I added a brand new pack of US-05 but that barely did anything. It was at 1.074 after 4 more weeks. I know I will need another type of yeast to bring the gravity down but shouldn't the S-04 and US-05 have done more? I calculated the ABV to be at 8.14% right now but I believe it should be up to about 10-11% before it becomes no longer effective. The temperature has been at a pretty consistent 65 degrees.

Any ideas on how to move forward from here and why my fermentation is stuck? What type of yeast do you guys think would be best to get the fermentation back up and going again? My goal is to get it down to at least 1.030. After that, I plan to transfer to secondary and add the following: 6 oz bourbon, vanilla beans, marshmallow extract, and cacao nibs, then ferment for a few more months before canning and storing for at least a year before opening. Please let me know if any of you have tried something like this and if you have any advice or tips. Any advice is much appreciated. Thank you!

 

[Kickass]

I hate to be the bearer of bad news but that’s probably where you’re going to finish.

You can try to warm a little and agitate to get the yeast moving but don’t expect much.

Pitching more yeast into a relatively inhospitable environment (higher alcohol, little oxygen, few remaining easily digestible sugars) won’t do much. Evidenced by your us-05 pitch.

In the future, huge batch of yeast that has high alcohol tolerance and high attenuation, lots of O2 and minimizing less fermentables (caramel/crystal malts and extract).

Maybe add some vanilla, coco, coconut, cinnamon and call it your Christmas pastry stout?

And welcome to HBT!

 

[pvtpublic]

First, what temp did you mash at?

Second, here's a few ideas;

1. Throw in champagne yeast.
2. Get a starter going and pitch at high krausen.
3.

You can try to warm a little and agitate to get the yeast moving but don’t expect much.

4.

Maybe add some vanilla, coco, coconut, cinnamon and call it your Christmas pastry stout?

5. Brew another, but really dry, and blend (not my personal course of action, but it might work for you)

 

[DBhomebrew]

Does champagne yeast ferment maltotriose? If not, it won't help. The original yeast didn't hit its alcohol limit, it hit its stop due to a complex sugar and alcoholic environment.

 

[pvtpublic]

Does champagne yeast ferment maltotriose? If not, it won't help. The original yeast didn't hit its alcohol limit, it hit its stop due to a complex sugar and alcoholic environment.

No it won't, you would need a B01 strain, and even then, I'm not sure how attenuative it would be on it. The suggestion of using champagne yeast or a high krausen yeast starter would be for an inadequate first yeast pitch (underaerated, underpitched, unhealthy, lacking viability, etc.).

 

[DBhomebrew]

The high krausen yeast starter, I understand. The champagne yeast into a wort full of complex sugars, not so much.

 

[InspectorJon]

A dose of alpha amylase enzyme can help to break down some of the unfermentable sugars. I used it before in an under fermented stout and got another 10 pints of attenuation. Gluco-amylase would possibly break down all the sugars and give you a very dry stout. I don't think I would use Gluco but you could give the A-amylase a shot. If you do a search here on HBT you will find lots of posts about stuck fermentations. You will find some additional information in This Thread

 

[pvtpublic]

A dose of alpha amylase enzyme can help to break down some of the unfermentable sugars. I used it before in an under fermented stout and got another 10 pints of attenuation. Gluco-amylase would possibly break down all the sugars and give you a very dry stout. I don't think I would use Gluco but you could give the A-amylase a shot. If you do a search here on HBT you will find lots of posts about stuck fermentations. You will find some additional information in This Thread

The problem with adding enzymes after pitching yeast is that there is no way to denature the enzymes. They'll continue breaking everything down until there's no flavor or body left.

 

[InspectorJon]

The a-amylase is limited in its ability. I don't know how to explain the difference well but it has to do with what part of the sugar molecule it works on. A-amylase will leave some unfermentable sugar and not break it all the way down like Glucoamylase.

 

[pvtpublic]

True. Alpha cuts starch molecules up at random, leaving varying lengths of sugars with varying levels of fermentability. So, I suppose you may be right, the alpha might be the way to go. But I wouldn't count on it leaving a high quality beer in the end. Drinkable yes, but no blue ribbons.

 

[dmtaylor]

I agree with others that additional enzymes are probably your best chance to take the gravity down much farther. And even then, good luck, because I know based on experience that the alcohol tolerance of S-04 is only 9%. Plus you used 4 pounds of crystal malts and 10 pounds of LME, which are less fermentable. Not sure how far US-05 might take it, hopefully a bit more, but with such a huge OG, most any beer yeast will poop out from the high alcohol. It is extremely unlikely you will end up anywhere close to 1.030 no matter what you do, and anything below 1.050 might be a miracle.

 

[Northern_Brewer]

Wort of 1.138 is a really stressful environment for yeast, you need to make sure you're pitching really happy yeast (vitality starters always a good idea), lots of oxygen etc. Also in this case you could have waited to add the LME/sugar, and feed it in as fermentation proceeds, just to reduce the initial osmotic shock.

See this :
https://quaff.org/wp-content/uploads/2012/11/HighGravityFermentation-1.ppt

But that's for next time, you are where you are. As others have said, it's tough for any new yeast to get a foothold in beer/wort that's 8% alcohol and no simple sugars. You need yeast that's up and running (vitality starter again) and give it simple sugars to get started on, whether that comes from the use of enzymes on the existing complex sugars, or adding some eg glucose.

 

[mac_1103]

I'm no expert, but this thread has me wondering if any of y'all might consider diluting with sterile water before pitching more yeast in a situation like this. Or is it just too late to make the environment less inhospitable?

 

[dmtaylor]

I'm no expert, but this thread has me wondering if any of y'all might consider diluting with sterile water before pitching more yeast in a situation like this. Or is it just too late to make the environment less inhospitable?

That’s not a bad idea at all.

 

[odie]

I'd warm it a little and give it more time. I've done RIS where is goes for a month before I add more sugar and keep going.

Granted 1.138 is up there. I just pitched US-05 into a 1.130 and it started chugging away strong within a few hours. Hope it keeps going cause I got 2# maple syrup planned for secondary phase.

 

[flow415]

Hey guys, sorry for the late reply but thank you all so much for your tips and advice. I really appreciate it!

I think I will first try to introduce some Alpha Amylase. Then, get a starter going with some champagne yeast and pitch at krausen. (Any suggestions on which specific yeast works best?) I'm sure the wort/beer could use some oxygen but would it mess it up if I use an aerator to introduce some air at this point with it being at about 8% ABV?

 

[VikeMan]

I'm sure the wort/beer could use some oxygen but would it mess it up if I use an aerator to introduce some air at this point with it being at about 8% ABV?

Oxygen turns ethanol into acetaldehyde. I wouldn't add O2 at this point.

 

[flow415]

Oxygen turns ethanol into acetaldehyde. I wouldn't add O2 at this point.

Ok, thank you!

 

[TheMadKing]

Hey guys, sorry for the late reply but thank you all so much for your tips and advice. I really appreciate it!

I think I will first try to introduce some Alpha Amylase. Then, get a starter going with some champagne yeast and pitch at krausen. (Any suggestions on which specific yeast works best?) I'm sure the wort/beer could use some oxygen but would it mess it up if I use an aerator to introduce some air at this point with it being at about 8% ABV?

Oxygen turns ethanol into acetaldehyde. I wouldn't add O2 at this point.

This, 100%. Do not add oxygen, you'll end up with a dumper

I think Krausening is your best bet here along with some alpha amylase. Pitch the enzymes and let it sit for a day or two, then pitch like 3 liters of vigorously fermenting wort with something like Scottish Ale, or San Diego Super, or even Kveik that has been highly oxygenated (like hit it with pure O2 an hour before pitching if you can).

You're probably hosed at this point though. Big beers are hard, and big beers with inadequate oxygen and yeast from the start are nearly impossible. Oxygen at the beginning is absolutely your best friend for a healthy fermentation in a wort that strong.

 

[flow415]

So, it looks like alpha amylase works best between 155-165F. Am I supposed to warm up my half fermented beer to that temp? Or would I just have to wait longer at say about 70 degrees? How long would it take for the amylase to be done working?

 

[TheMadKing]

So, it looks like alpha amylase works best between 155-165F. Am I supposed to warm up my half fermented beer to that temp? Or would I just have to wait longer at say about 70 degrees? How long would it take for the amylase to be done working?

it works BEST at those temps, it will work at 70 degrees but take longer. That was why I suggesting waiting a couple days between adding the enzyme and pitching more yeast

 

[flow415]

it works BEST at those temps, it will work at 70 degrees but take longer. That was why I suggesting waiting a couple days between adding the enzyme and pitching more yeast

Got it. Thank you!

 

[passedpawn]

1. Add alpha amylase immediately.
2. Add a diastaticus yeast like wyeast 3711.
3. Stand back.

 

[pvtpublic]

You could also throw some bugs in there and let it ride a year or more to develop a nice sour funkiness.

 

[chthon]

You could also throw some bugs in there and let it ride a year or more to develop a nice sour funkiness.

The original British way. These kinds of beers took 1 to 2 years conditioning in large vats. Expecting to brew the same beer in a timespan of two months seems optimistic.

 

[TheMadKing]

1. Add alpha amylase immediately.
2. Add a diastaticus yeast like wyeast 3711.
3. Stand back.

*shiver*

Those scare me after a diastaticus infection where 3 batches in a row attenuated to about 100%, but they certainly work.

I switched to iodophor after that experience

I wonder how Voss Kveik would do though?

 

[flow415]

OK, so I created a yeast starter and added a fresh pack of WLP099. I aerated the wort before I added the yeast and it immediately started to show some activity on the stirplate. However, it slowed down within a day. It's been 5 days now and there was never any krausen. I doubt there's going to be much more activity at this point. Should I still pitch it into my stuck beer that I added alpha amylase to over a week ago, or should I get a new yeast and try to get it to high krausen? Tbh, I'm not sure why it never really activated. For the starter, I used 800mL of water, 200g of dme and yeast nutrient. In the past, I had a couple saved yeast get really activated on the same starter before so I'm not sure why it appeared weak this time. I ordered the WLP099 from morebeer.com and used it right away.

Suggestions on how next to proceed? Anything helps! Thanks in advance!

 

[hotbeer]

So the SG hasn't changed at all since your first posting about this Dec. 10th?

SG is what tells you for certain something is going on or not. Bubbles aren't a good indicator of anything for certain.

 

[IslandLizard]

For the starter, I used 800mL of water, 200g of dme

Where did you get that ratio from? You made a yeast "starter" in (fairly high gravity) 1.074 wort.
Most yeast starters are 1:10, DME to water, by weight, for a resulting 1.037 gravity.

In stirred starters you would not see much activity, except some foam at times, as the main object is to grow more cells, and increase their vitality.

 

[flow415]

So the SG hasn't changed at all since your first posting about this Dec. 10th?

SG is what tells you for certain something is going on or not. Bubbles aren't a good indicator of anything for certain.

I haven't checked the gravity of it but I was just thinking if the yeast really took off, there would've been a lot of krausen.

 

[flow415]

Where did you get ratio from? you made a yeast "starter" in (fairly high gravity) 1.074 wort.
Most yeast starters are 1:10 DME to water, by weight, for a 1.037 gravity.

In stirred starters you would not see much activity, except some foam at times, as the main object is to

Correction, I used 100g of dme. Sorry!

 

[VikeMan]

Reading through this thread again... I didn't see this mentioned/asked... How are you measuring the gravity (of the beer, not the starter)?

 

[flow415]

Reading through this thread again... I didn't see this mentioned/asked... How are you measuring the gravity (of the beer, not the starter)?

How did i measure the gravity of the starter? I didn't measure it. I do know that bubbles were coming out of my airlock for sure when I first put it on the stirplate after I aerated the wort and added the yeast.

 

[Alan Reginato]

I don't know what you are going to have in your fermentor when you finish it. Adding dry saison yeast maybe is another shot you could fire.

BTW, how you're measuring the gravity of the beer? Refractometer?

 

[VikeMan]

How did i measure the gravity of the starter?

No, the beer.

 

[flow415]

Reading through this thread again... I didn't see this mentioned/asked... How are you measuring the gravity (of the beer, not the starter)?

How did i measure the Gravity of the starter? I didn't measure it. I do know that bubbles were coming out of my airlock for sure when I first put it on the stirplate after I aerated the wort and added the yeast.

No, the beer.

I'm using a normal hydrometer.

 

[flow415]

I don't know what you are going to have in your fermentor when you finish it. Adding dry saison yeast maybe is another shot you could fire.

BTW, how you're measuring the gravity of the beer? Refractometer?

I'm using a hydrometer.

 

[IslandLizard]

I do know that bubbles were coming out of my airlock for sure when I first put it on the stirplate [...]

On an aside note, yeast starters need to have access to unlimited air/oxygen as that coaxes the yeast into aerobic respiration causing cell multiplication (through budding), rather than fermentation (anaerobic respiration).

In starters, an airlock should therefore be avoided, and instead, use a loosely crimped aluminum foil "tent" over the starter vessel's opening or a gas permeable (breathable) foam plug. Air (O2) can enter and CO2 can be expelled.

 

[passedpawn]

I haven't checked the gravity of it but I was just thinking if the yeast really took off, there would've been a lot of krausen.

Check your specific gravity right now. Report back.

 

[Bluntsworth]

Would distiller's yeast work? Is that a diastaticus yeast? I have a stuck Belgian Quad I need to figure out.