Stout never finishes fermentation, all others do

[pola0502ds]

I brew a oatmeal stout, the first to times it fermented out. The last 2 times it's stuck at 1030.

I used Safeale s-04 yeast. The first day it was fermenting, I high activity. The second day I the air lock was moving well but the krausen was gone. And this happened the last 2 times i brewed the beer.

What the heck is going on?

The last time I brewed this it fermented at 64 degrees so I thought that was the problem but this time I fermented at 70 degrees and it didn't fix the problem, krausen was completely gone after just 2 days.

 

[Yooper]

I brew a oatmeal stout, the first to times it fermented out. The last 2 times it's stuck at 1030.

I used Safeale s-04 yeast. The first day it was fermenting, I high activity. The second day I the air lock was moving well but the krausen was gone. And this happened the last 2 times i brewed the beer.

What the heck is going on?

The last time I brewed this it fermented at 64 degrees so I thought that was the problem but this time I fermented at 70 degrees and it didn't fix the problem, krausen was completely gone after just 2 days.

It could be recipe related (lots of crystal malts will have more residual sweetness and often a higher FG) and mash temp related (higher mash temps will stop at a higher FG). What's the recipe?

 

[stratslinger]

How much time, total, are you giving the beer before you're giving up on it as stuck? Just because the krausen has fallen doesn't mean that fermentation has completed. I've had beers that took weeks to finish up - one was at about 1.020 around 4 weeks in, the krausen had dropped no more than 10 days in. I waited maybe another 5 days, and the beer hit 1.015.

 

[pola0502ds]

The recipe is:

20# 2row
4# oats
4# oat malt
4# crystal 45
3# chocolate
1# roasted barley

Mash at 158

It's been 3 weeks at 1030 for the last batch that is still in the secondary and I just did a batch this weekend.

 

[jmo88]

The recipe is:

20# 2row
4# oats
4# oat malt
4# crystal 45
3# chocolate
1# roasted barley

Mash at 158

It's been 3 weeks at 1030 for the last batch that is still in the secondary and I just did a batch this weekend.

1.030 sounds about right for that grist mashed at 158F

 

[JacobS]

^ +1

 

[wailingguitar]

At 5 gallons, that's a damned big beer... at 10 gallons it would still be a very solid beer...

Your recipe doesn't state the volume you brewed, what was it and what was your OG?

 

[ChillWill]

Holy oats Batman! That's a lot of oats.

Also got a lot of unfermentable sugar in there. Drop the mash and special malts if you want lower gravity.

What did your others get down to?

 

[bethebrew]

Holy oats Batman! That's a lot of oats.

Also got a lot of unfermentable sugar in there. Drop the mash and special malts if you want lower gravity.

What did your others get down to?

Quaker would be proud...

 

[JonK331]

1.030 sounds about right for that grist mashed at 158F

Yup, I'm surprised you got it that low. 5 or 10 gallon batch?

 

[bethebrew]

Yup, I'm surprised you got it that low. 5 or 10 gallon batch?

If it were 5 gallons he would have had it for breakfast with a little milk and brown sugar maybe some raisins or sliced bananas...that's 36 lbs of stuff.

 

[bruin_ale]

Even at 10 gallons it's way big. 15 gallons starts to approach oatmeal stout style guidelines.

 

[pola0502ds]

It was a 10 gallon batch, OG is 1.081.

I don't care about the oatmeal stout style guidelines, I go by my guidelines and if you brew this beer you will see just how damn good it is. There is so much oat in it because we like the oat flavor and want it to be strong.

 

[BradleyBrew]

It was a 10 gallon batch, OG is 1.081.

I don't care about the oatmeal stout style guidelines, I go by my guidelines and if you brew this beer you will see just how damn good it is. There is so much oat in it because we like the oat flavor and want it to be strong.

BAM! Tell'em

 

[pola0502ds]

Can someone explain what the temperature of the mash has to do with how the beer ferments out? Also, which items have a lot of non fermentable sugars in it?

 

[Yooper]

It was a 10 gallon batch, OG is 1.081.

I don't care about the oatmeal stout style guidelines, I go by my guidelines and if you brew this beer you will see just how damn good it is. There is so much oat in it because we like the oat flavor and want it to be strong.

Then I don't see the problem. You love it.

It simply will NOT go lower than 1.030 if you mash that grist at 158. Your exact words were, "What the heck is going on?" and we told you. If you love it, don't fix it.

 

[Tinga]

Can someone explain what the temperature of the mash has to do with how the beer ferments out? Also, which items have a lot of non fermentable sugars in it?

at that temperature the enzymes that cut the longer unfermentable sugar chains into fermentable sugars does not work as well as at a lower temperature. so when you mash that high you are left with much more unfermentable sugars and thus a high fg.

 

[bruin_ale]

I was just indicating that it could have been any volume up to 15G, I love imperial oatmeal stouts - I think that OG is great for that.

Mashing at a higher temp creates more long-chain sugars that ale yeast aren't able to break down. I'm not sure how fermentable oats/oat malt are, so I won't comment on those, but I believe the crystal/chocolate/roasted all contribute non-fermentables.

Did you use a single packet of S-04 per 5G? I'm not sure I'm totally convinced that it's impossible to get below 1.03 when mashed at 158, but that recipe and the mash temp do have the makings for a beer with a high final gravity.

 

[pola0502ds]

Well, I learned something today. I do nothing but read books on brewing and I never heard of that. Or maybe I did but forgot. Thanks guys.

I created a 2 quart starter for the 10 gallons as I do with all my beers regardless of how big the beer may be.

 

[bruin_ale]

Well, I learned something today. I do nothing but read books on brewing and I never heard of that. Or maybe I did but forgot. Thanks guys.

I created a 2 quart starter for the 10 gallons as I do with all my beers regardless of how big the beer may be.

Glad we could help!

Just a quick note on the yeast amount. A single 11.5g dry yeast pack has about 200 billion cells, if you do a 2qt starter on a stir plate you'll be a little shy of the 550 billion cells you need by about 100 billion (according to mrmalty.com)

That's probably not the end of the world as I think mrmalty is a conservative estimate - but if you're just doing a simple starter (ie. not a stir plate, no oxygenation) you're going to be about 250 billion cells short, so pretty significantly underpitching, which is also going to hurt your attenuation levels.

When using dry yeast, it's probably easier/more cost effective to just get an extra packet of dry yeast and use one per 5G than to build a starter. The calculator says you should use 2.6 packets of dry yeast for 10g of 1.08.

 

[pola0502ds]

Bruin Ale, thanks for the tips.. I appreciate it!