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General Category => All Grain Brewing => Topic started by: smortil987 on December 10, 2010, 09:22:10 PM

Title: Stuck Fermentation Question
Post by: smortil987 on December 10, 2010, 09:22:10 PM
Hey guys...  My first post here on the boards about my first all grain batch....

I believe I have a stuck fermentation.  I brewed an all grain pale ale with a SG of 1.054.  I pitched Safale US-05 directly on top of my wort at around ~80 degrees.  The airlock began to bubble like crazy within ~36 hours, but the bubbling only lasted ~24 hours then stopped completely.  I let it sit an extra day and got a gravity reading of 1.023 (~56% attenuation).  I let it sit for about 7 more days and the gravity was still at 1.023.  I have it in my fermentation fridge at 65 degrees.  I re-pitched another pack of US-05 directly on top of the wort and set my fridge at 70 degrees.  I have not seen any activity in the airlock.  Before re-pitching the yeast, I agitated the wort and got good foam on top to ensure I had sufficient oxygen. 

Anybody have any thoughts on this?  Thanks...
-Sal
Title: Re: Stuck Fermentation Question
Post by: denny on December 10, 2010, 09:27:37 PM
What was your recipe and mash temp?  Depending on those, it might be done.
Title: Re: Stuck Fermentation Question
Post by: smortil987 on December 10, 2010, 09:32:42 PM
My recipe was:

8 pounds of pale malt
1 pound of Crystal malt (60L)
1 pound of honey (added last 15 min)
1oz Cascade hops
1oz Centennial hops

I mashed out at ~153 degrees and sparged at ~170.

Title: Re: Stuck Fermentation Question
Post by: denny on December 10, 2010, 09:39:23 PM
I don't see any red flags there...
Title: Re: Stuck Fermentation Question
Post by: smortil987 on December 10, 2010, 09:50:27 PM
I guess what I was concerned about was it being my first all-grain batch and debating whether I should aerate the wort or not (I did not do it for this batch).  The science behind aerating makes sense (a full boil depletes all the oxygen) and thought there may have been a problem because I didn't aerate.  I guess I was just expecting a few days worth of bubbling in the airlock and a gravity lower then 1.023.  I think I'm just going to keg as usual and see what happens.
Title: Re: Stuck Fermentation Question
Post by: denny on December 10, 2010, 09:55:34 PM
Well, you pitched at such a high temp that it could be finished quickly.  Personally, I recommend getting it into the mid 60s before pitching, but that's a different matter.  1 pack of 05 should have been plenty of yeast for a beer of that OG.  It really sounds like a wort fermentability issue to me.  How sure are you that your thermometer is correct?
Title: Re: Stuck Fermentation Question
Post by: smortil987 on December 10, 2010, 10:04:23 PM
Fair enough...  I'm so used to going by extract kit directions where is says "pitch between 80-90."  Well I bought the thermometer brand new  ;D.  I'm hoping it right  haha.

So you advocate pitching at 65 then?

And thanks in advance for your insight.

Title: Re: Stuck Fermentation Question
Post by: narvin on December 10, 2010, 10:06:49 PM
I think Denny is talking more about mash temp.  I had a digital probe thermometer from Target that was about 5 degrees high... mashing at 158 will definitely make your wort less fermentable.  I've also seen that identical "lab" thermometers at the LHBS are often 2 degrees off from each other when I line them up and look at them.
Title: Re: Stuck Fermentation Question
Post by: denny on December 10, 2010, 10:50:16 PM
Fair enough...  I'm so used to going by extract kit directions where is says "pitch between 80-90."  Well I bought the thermometer brand new  ;D.  I'm hoping it right  haha.

So you advocate pitching at 65 then?

And thanks in advance for your insight.



Yeah, my experience is that my beers turn out better when I pitch cooler.  But I doubt that had anything to do with your attenuation issue.  It's just an observation.  If your thermometer is off reading the mash temp, though, you could be mashing at too high a temp and reduce the fermentability of your wort.
Title: Re: Stuck Fermentation Question
Post by: saltydawg on December 10, 2010, 11:27:13 PM
I'm sure others know more about this but... I've read when using simple sugars in a recipe it's sometimes beneficial to put the simple sugars in at the end of primary fermentation. Otherwise the yeast will digest the simple sugars first, before the maltose, and then start to lose the ability to digest the maltose, resulting in poor attenuation. Kinda like a kid who eats dessert first and has no appetite for supper. I'm sure it's a more pronounced effect at higher simple sugar to maltose ratio, but you get the idea.

Also, I really think by not aerating, you really didn't give the yeast a good start.

All that, and I agree with the previous posters that mash temperature is critical.

And the crystal malt....

I guess it could be a combination of contributing factors... :-\

Anyway, your FG isn't totally terrible. If it tastes good, drink up! :)
Title: Re: Stuck Fermentation Question
Post by: denny on December 10, 2010, 11:57:07 PM
I'm sure others know more about this but... I've read when using simple sugars in a recipe it's sometimes beneficial to put the simple sugars in at the end of primary fermentation. Otherwise the yeast will digest the simple sugars first, before the maltose, and then start to lose the ability to digest the maltose, resulting in poor attenuation. Kinda like a kid who eats dessert first and has no appetite for supper. I'm sure it's a more pronounced effect at higher simple sugar to maltose ratio, but you get the idea.

Also, I really think by not aerating, you really didn't give the yeast a good start.

All that, and I agree with the previous posters that mash temperature is critical.

And the crystal malt....

I guess it could be a combination of contributing factors... :-\

Anyway, your FG isn't totally terrible. If it tastes good, drink up! :)


While all of that is possible, my experience is different.  I usually add sugar to the boil and haven't had any problems because of it.  Dry yeast shouldn't really need aeration.  And while a lb. of crystal is more than some people may like, I often use that much (my Rye IPA recipe, for example, uses 1.25 lb.) and I haven't had high FGs from it.  Not tryin' to bust yer chops, just relating my experience.
Title: Re: Stuck Fermentation Question
Post by: Hokerer on December 11, 2010, 12:00:48 AM
I'm sure others know more about this but... I've read when using simple sugars in a recipe it's sometimes beneficial to put the simple sugars in at the end of primary fermentation. Otherwise the yeast will digest the simple sugars first, before the maltose, and then start to lose the ability to digest the maltose, resulting in poor attenuation. Kinda like a kid who eats dessert first and has no appetite for supper. I'm sure it's a more pronounced effect at higher simple sugar to maltose ratio, but you get the idea.

I would seriously doubt that one pound of honey would be enough to cause such a problem.  In fact, I regularly use a pint jar full (weighs out to about 22 oz of honey) added late in the boil with absolutely no problems.
Title: Re: Stuck Fermentation Question
Post by: Hokerer on December 11, 2010, 12:01:56 AM
How sure are you that your thermometer is correct?

and you hydrometer.  Both of mine read .003 off
Title: Re: Stuck Fermentation Question
Post by: saltydawg on December 11, 2010, 12:24:22 AM
No 'busting of chops' inferred by me. ;) I'm just participating in the discussion. But re-read my post. I didn't say 1 pound of honey caused his problem. I'm laying out possibilities that COULD contribute. These are all factors that present possiblilties. Perhaps even pieces of a puzzle that form the big picture. None of the things I stated are wrong all the time. Maybe or maybe not in this case, but not all the time. None of us can pinpoint the exact cause with 100% certainty in any one specific case.

BTW...Good point about the dry yeast/oxygen thing. At those cell counts, not much growth needs to happen.

So, I'm jus' sayin'...

Title: Re: Stuck Fermentation Question
Post by: denny on December 11, 2010, 01:39:52 AM
None of the things I stated are wrong all the time. Maybe or maybe not in this case, but not all the time. None of us can pinpoint the exact cause with 100% certainty in any one specific case.

So, I'm jus' sayin'...



And in this I absolutely agree.
Title: Re: Stuck Fermentation Question
Post by: tschmidlin on December 11, 2010, 07:14:25 AM
It sure sounds to me that it's a fermentability problem.  Your mash temp could be off, your mash procedure could be off, it's hard to say.  Take a cup and add some bread yeast, see if the gravity drops any more.  If it doesn't, it's not going to unless you do something like add some amylase.  Just a thought.