S-04 Slow Fermentation, or Stuck?

[ubermench]

Hey all, I've worked my way into a corner and could use some help! Two weeks back, I brewed up a partial mash imperial Irish red for an upcoming club competition, from a recipe I had been meaning to brew up for a while. OG was 1.064, and I pitched my bubbly rehydrated Safale S-04 starter at 69F before transferring to my fermentation freezer set to 63F.

This was my first time working with S-04, so I was unsure of what to expect, but wanted to keep the beer cool due to reading of the nasty esters when the S-04 goes over the high 60's. Fermentation started slowly after ~ 16 hours, and bubbled away with nice krausen, but very slowly compared to my experience with most of the White Labs strains.

Fermentation kept going at a slow and steady pace over the next week, with beer temps fluctuating from 59 - 62 F due to an unexpected cold front, down to 1.042 after a week, and now 1.034 after two weeks. Checking it earlier to measure gravity, the krausen has dropped, and I'm not seeing any more bubbling. My target FG was 1.016, so I'm waaaaaay off the mark here, and don't know what to do!

Has my beer stopped, or merely stalled / slooooooowed down to a crawl? More importantly, what should I do? Shake it a bit more? Warm it slightly and pitch more S-04? Looking for some sage wisdom - Cheers!

Recipe follows:

Yeast: Safale US-04
Batch Size (Gallons): 5
Original Gravity: 1.064
Final Gravity: 1.012
ABV: 6.2%
Boiling Time (Minutes): 60
Primary Fermentation (# of Days & Temp): >7
Secondary Fermentation (# of Days & Temp): >14


Mash
0.50 lbs. Vienna Malt
0.25 lbs. Flaked Barley
0.10 lbs. Roasted Barley
0.75 lbs. Cara-Pils/Dextrine (Carafoam 1.5-2 L)
1.00 lbs. Cara/Crystal Malt 60L
1.00 lbs. Torrified Wheat – (for head retention)

Boil
6.00 lbs. Pale Liquid Malt Extract

1.00 oz Fuggles (boil 60 min.)*
0.50 oz. Irish Moss (boil 15 min.)
1.00 oz East Kent Goldings (boil 5 min.)*
1.00 lbs. LIGHT Brown Sugar (boil 5 min.)

Sidebar: just to make things worse, while double-checking my recipe this evening, I realized that I grabbed the wrong recipe from what I had intended, and instead brewed up something red-like! No idea where I got this from, and my Google-fu isn't turning up anythig either...Curious to see how this turns out (if it will ferment more!)

 

[mredge73]

S-04 is a high flocculation yeast, so it falls out of solution much better than most yeasts.
Because of this it doesn't finish as well as other yeasts, that is a big reason why the medium flocculation yeast S-05 is preferred.
So rouse the yeast a little with a gentle stir or slight shake; do not splash.
Also warm it up, I would take it as high as 72-75F to really finish up.
Esters are no longer a concern for you as most esters are formed during the growth phase right after pitch and you are not growing any new yeast.
On paper S-04 has less ester formation than the commonly used S-05. In practice this may be different but I cannot comment on this as I have had no problems with S-04.

 

[mongoose33]

I haven't had any problem using S-04 and not having it finish.

However, I typically ferment at 64-65 degrees; I think you're just too cool.

So--warm it up to 66 at least, maybe 68, and swirl the fermenter to try to rouse some of the yeast back into suspension.

 

[ubermench]

S-04 is a high flocculation yeast, so it falls out of solution much better than most yeasts.
Because of this it doesn't finish as well as other yeasts, that is a big reason why the medium flocculation yeast S-05 is preferred.
So rouse the yeast a little with a gentle stir or slight shake; do not splash.
Also warm it up, I would take it as high as 72-75F to really finish up.
Esters are no longer a concern for you as most esters are formed during the growth phase right after pitch and you are not growing any new yeast.
On paper S-04 has less ester formation than the commonly used S-05. In practice this may be different but I cannot comment on this as I have had no problems with S-04.

I haven't had any problem using S-04 and not having it finish.

However, I typically ferment at 64-65 degrees; I think you're just too cool.

So--warm it up to 66 at least, maybe 68, and swirl the fermenter to try to rouse some of the yeast back into suspension.

Alright, here's hoping it's just stalled out, and not gone dormant again! Or could I have sent them dormant again? Fermentis sets 59-68F as ideal, and I'm hanging on the lower bound,
as many different posts posts here talk about off flavors from ester production above 63-65 F, which I was afraid of, haha.

Clearly, I'll be warming it up to 65 - 68ish. Would gently stirring the fermenter using a sterilized brew paddle be the best way to reintroduce the attenuated yeast into the wort/beer mixture, or would swirling the fermenter be better? Do I want to truly stir up the flocculated cake / trub to reintroduce them, or is that overkill?

I'll be racking to secondary once it hits close to FG, so I'm not concerned about particulates in doing this. I know I want to minimize oxidation and splashing, but this is my first time such such a high flocculation strain, so I'm a bit out of my element!


If I don't see the gravity dropping again within 24-48 hours or so, would it be wise to pitch another packet of S-04? The beer is sitting at ~3.8% now, way too sweet and short of the 6.2% I was going for. Submission for the competition is in about 3 weeks, so I'm kinda pulling my hair out here,,,

 

[mredge73]

Don't re-pitch, this isn't necessary as you have plenty of yeast.
Stir up the yeast in whatever manner you feel comfortable with, it will all fall back out in a few days so you can mix it up good. No splashing and don't be too violent with it or CO2 will come out of solution and bring half of your beer with it.
Warm it up, at this point you can go into the lower 70's if you really want it to get going or 68 if you want to be conservative. Yeast produce esters during the growth phase, they will clean up esters now.
I suspect that pitching this yeast in warm wort is what is causing most of the ester problems people are experiencing. I wouldn't be surprised if you have trouble getting it lower than 1.02, many extract brews have this issue.
However at 1.03 it is not finished, the yeast just fell out of solution too fast and need some encouragement to finish.

 

[ubermench]

Don't re-pitch, this isn't necessary as you have plenty of yeast.
Stir up the yeast in whatever manner you feel comfortable with, it will all fall back out in a few days so you can mix it up good. No splashing and don't be too violent with it or CO2 will come out of solution and bring half of your beer with it.
Warm it up, at this point you can go into the lower 70's if you really want it to get going or 68 if you want to be conservative. Yeast produce esters during the growth phase, they will clean up esters now.

Took your advice, and I gently stirred up the yeast cake after letting it warm to 68F. As of this evening, I've got more activity in the fermenter, and gravity has continued to drop to 1.029! Getting there...


Just to clarify, what did you mean by the CO2 "bringing half of my beer with it?" I thought that the goal was to avoid splashing / introducing more dissolved oxygen? How would knocking CO2 out of solution affect the beer, other than allowing for introduction of more oxygen?


As for growth, I thought that the whole point of rousing the yeast was to bring them out of flocculation / the stationary phase, and back into growth? Since I need fermentation to continue, that would imply additional growth phase, and thus ester production, no? Or am I confused?

I suspect that pitching this yeast in warm wort is what is causing most of the ester problems people are experiencing. I wouldn't be surprised if you have trouble getting it lower than 1.02, many extract brews have this issue.
However at 1.03 it is not finished, the yeast just fell out of solution too fast and need some encouragement to finish.

That would definitely seem to make sense! I've just been a bit (over)paranoid with temperature for this batch due to this. We'll see how much more attenuation I get - even though I'm still a partial masher, I make sure to oxygenate my wort well before pitching a healthy yeast population, which has always done me well for hitting close to the desired FG.

Thanks for all of your help!

 

[mredge73]

Yeast can only multiply/grow when oxygen is available but you don't want to introduce more oxygen at this point as this will cause more harm than good.
You have plenty of yeast, you don't need more. You need them to wake up and eat instead of sleeping on the bottom, yours need a bit of encouragement for whatever reason.

Taking CO2 out of solution will help the yeast but if there is a lot of dissolved CO2 you could have a soda explosion if you are too violent with your stirring. I am still cleaning up a wine degas incident from last year in my brewery.
Brewing yeast has a pretty high tolerance to CO2 so I wouldn't even bother trying to degas.