1084 stopped at 1.024

[SteveHeff]

I recently brewed up an imperial stout. OG was 1.076 and my anticipated FG was 1.012. My yeast stopped stone cold at 1.024 and I have not been able to increase any activity with heat, agitation or yeast nutient. Here's the question: how likely is it that the addition of oxygen to my wort would increase my attenuation? I've never brewed a beer this big before however I've never had 1084 stop working this early in the process. I'll supplement more info about the beer recipe when I have access from my home computer. Thanks for any input.

 

[Rivcyclist]

I recently brewed up an imperial stout. OG was 1.076 and my anticipated FG was 1.012. My yeast stopped stone cold at 1.024 and I have not been able to increase any activity with heat, agitation or yeast nutient. Here's the question: how likely is it that the addition of oxygen to my wort would increase my attenuation? I've never brewed a beer this big before however I've never had 1084 stop working this early in the process. I'll supplement more info about the beer recipe when I have access from my home computer. Thanks for any input.

Did you use a yeast starter? Imperial stouts need a lot more yeast than a normal batch, if you only tossed in 1 package of 1084 you'll probably be short. Also, you need to oxygenate before pitching once the wort has cooled to the proper temperate. Using the right amount of yeast and providing an oxygen rich environment helps in a big way. From what I understand you shouldn't oxygenate at this point, it will make the beer taste bad. Although I have only made a few big beers so I could be wrong on some of this, others with more experience can weigh in. Your best bet may be to pitch a hydrated package of S-04 if the first yeast has petered out. You can also try agitating (shaking) your fermentation vessel and getting the current yeast back into suspension, and warming up the vessel some, maybe that will wake em' up! Let us know how it turns out.

 

[Calder]

1.076 is not a particularly big beer. Big beers an present some problems, but this is not in that arena.

No, do NOT aerate!

You have about 69% attenuation, the yeast is supposedly good for 71 to 75%. What was the recipe? Extract or all-grain? If extract, how much specialty grain did you use, and what was it; that will affect attenuation. If all-grain, what temp did you mash at. Need more information to help you. If it is extract and a lot of specialty grain, you may be done.

 

[couchsending]

Some of the best stout’s in the world have final gravities much higher than that. I don’t think I would ever want a stout to finish much lower than 1.020. Kind of depends on recipe design though. I’ve been trying to get one to finish at 1.030 lately and can’t, it always ends up lower.

One of the highest regarded non adjunct robust porters is a 7.5% beer with a FG of 1.030.

Is your beer overly sweet?

 

[leonardoreges]

Oxigenation is needed at pitching time for liquid yeasts.
If you do it now you’re gonna cold oxidate your beer.
Probably primary fermentation stopped because all fermentable sugar have already been gone.
Agree that you need to give better information about your recipe for definitive answer, but at first look I say leave it as it is.

 

[hlmbrwng]

I recently brewed an imperial stout, starting at 1.100. I used too much munich and not enough 2-row. It stopped at 1.050! Well, I kept going with it and did what I originally intended to do. I add dextrose and DME (about half and half). The effective OG was about 1.130. The entire additional sugars fermented out and I was back down to 1.050, so I know the issue wasn't the yeast.

Anyway, it tastes pretty damn good and I can't wait until it has conditioned long enough. Taste it before you do anything else to it. You might like it a lot.

 

[kh54s10]

I agree that it could be finished. I would taste it. If it tastes right, just accept the FG.
You might try a higher attenuating yeast.

Whatever you do, do not aerate. That would oxidize the beer.

 

[glugglug]

What temperature are you fermenting at?

 

[Beer-lord]

I brewed a 1.066 milk stout recently with 001 and mashed at 156 and it won't go below 1.029. I gave up and kegged it and it's a tad sweet but not bad.
However, every time I mash at 156 I've had this problem no mater the year, the pitch rate, the aeration or temperature, it's the fermentables for me. So, my future stouts will be mashed no higher than 154.

 

[SteveHeff]

The beer is kegged and has been carbonating for the last 3 weeks. When I was talking about aeration, I meant at the time of pitching yeast, not at any time after that. Sorry for how contriteness the initial post was...I was at work and only had a couple seconds.

Here's the recipe:

11# maris otter
2# flaked oats
1# chocolate malt
12 oz flaked barley
8 oz C120
6 oz roasted barley
4 oz de-bittered black malt
Fuggles and Golding hops.

I pitched my yeast starter, which I bulit up over 2 days, over my 1.076 wort. I had great activity over the first 5 days. By day 8, my gravity was 1.024. I was fermenting at 66-70F, depending on the time of day it was in the house. Other than pouring the wort through a strainer and shaking the bucket, I don't use any other method of oxygenate it.

It tastes great. One (if not THE) of the best stouts I've ever made. Quality-wise, it's a knockout. I shouldn't even be complaining but I really wanted to get it down to 1.020. Good body with a bit of a punch, you know?

So that's where it is currently.

 

[couchsending]

I brewed a 1.066 milk stout recently with 001 and mashed at 156 and it won't go below 1.029. I gave up and kegged it and it's a tad sweet but not bad.
However, every time I mash at 156 I've had this problem no mater the year, the pitch rate, the aeration or temperature, it's the fermentables for me. So, my future stouts will be mashed no higher than 154.

Are you really sure that it's the mash temp. I've read a lot of info on the fact that mash temps don't really have that much affect on the FG as we think. I believe someone on BA did some 60 minutes mashes at like 152 and 162 and the difference was something like 2 or 4 gravity points. Mash length however can have a much larger affect on FG. I've made three stouts or robust porters where I'm trying to get the gravity to finish at 1.030 and I can't do it. First was mashed at 158 for 45 then 168 for 15. Went from 1.080 to 1.020 with 002. Second was mashed at 158 for 30, 162 for 15. Went from 1.080 to 1.020 with 002. Last one was mashed at 158 for 15, then 162 for 15. Went from 1.074 to 1.024 with ECY10. Headed in the right direction.

I don't think that mashing at 156 made your milk stout stop at 1.029. Something else was at play.

 

[hlmbrwng]

I've made three stouts or robust porters where I'm trying to get the gravity to finish at 1.030 and I can't do it.

If you haven't, try using something like 20L Munich Malt. I believe that this, as opposed to 10L, does not have quite enough diastatic power for full conversion. And use less 2-row. Because even if you don't get much diastatic power from the Munich, if there is enough 2-row, it will still fully convert.

I have experienced this twice. The 1.050 FG beer I mentioned above was more than 60% 20L Munich (don't remember how much off the top of my head, but twice the amount of 2-row. It's pretty sweet, relative to most other imperial stouts, but I'm trying to balance it out with oak, bourbon, etc. I think it'll still be delicious.

 

[couchsending]

If you haven't, try using something like 20L Munich Malt. I believe that this, as opposed to 10L, does not have quite enough diastatic power for full conversion. And use less 2-row. Because even if you don't get much diastatic power from the Munich, if there is enough 2-row, it will still fully convert.

I have experienced this twice. The 1.050 FG beer I mentioned above was more than 60% 20L Munich (don't remember how much off the top of my head, but twice the amount of 2-row. It's pretty sweet, relative to most other imperial stouts, but I'm trying to balance it out with oak, bourbon, etc. I think it'll still be delicious.

But then the beer tastes like a beer with tons of Munich which I’m not a fan of personally. I think I have it figured out with just shortening mash length. The 1.074 beer that stopped at 1.024 should probably stop at closer to 1.030 with a higher starting gravity. Hopefully make an attempt next week.

 

[Vandulus]

With higher OG beers and if you have a fermentation chamber, it helps to start fermentation at the low end of the yeast temps and raise it daily during primary. I have an IPA with an OG of 1.079 that stalled at 1.034 and is now slowly fermenting again that the temperature is at the yeast's high end of the range. You could also try adding some alpha amylase and stirring it up to see if that will help break down some additional sugar to ferment out...