Stuck Fermentation?

So I know this may belong in the beginners forum, but I'm putting it here as I don't feel much like a noob anymore (so please move if I'm wrong). Anywho, I brewed up an Imperial Cream Stout about 4 weeks ago (recipe here) that came out to an OG of 1.099.

I pitched two packets of S-04 directly onto the wort per the directions on the yeast packet. For the first two weeks, the wort was between 64 and 66 degrees. I took a sample two weeks ago and the gravity was 1.052. Tonight, it was 1.051. I've let the beer come up to 70 degrees. I've been giving the fermenter a gentle shake (basically just twisting the fermenter firmly back and forth) every few days.

Is it possible that the fermentation is stuck? If so, should I just pitch another packet of S-04? Champagne yeast? I'm out of ideas...I plan on letting the brew sit for a while yet, so time isn't a factor. I just don't want to come back in 2 months to find the gravity in the same place it is now.

Thanks!

Bob

Should go lower than that. I'd give it a week at 70 and if it doesn't move pitch some more yeast. Make sure to hydrate your yeast first. Pitching directly into the wort is a bit rough.

I suspect the problem was probably inadequate oxygen for the yeast to grow and handle the high sugar level. That and not hydrating the yeast is my bet on the issue. I also find that 64 to 66 i a little low for s04. I have had problems with it dropping out early in that range. Not sure if that is other's experience but it was mine.

So my suggestion is 1) let sit at a week at 70 and see where it is at. If no real progress then pitch some hydrated s04 yeast and give it another couple weeks at 70F. The Extra yeast wont hurt anything and S04 can definitely handle the alcohol level you have.

Based on the recipe I would expect your FG to be pretty high.. but not freaking 1.05.. 1.03 maybe but not 1.05.

I suspect inadequate oxygen. If I did a brew that large I'd have hit it with pure O2 at pitch and again after 12 hours or so. Check out a pure O2 kit if this becomes a nagging problem.

i very much doubt the problem is insufficient oxygen. i've done beers bigger than that & just tossed in non-rehydrated S-05 with no pure O2 and had no stall.

champagne yeast won't do squat for this, its only useful for carbonation, dont bother with it

part of your problem is that is a ton of unfermentables (2lbs crystal + 1lb lactose + ~10lbs of dark extract in 4gals!). it really should still have reached lower than that, but it isn't helping. i blame the S-04, i think its a terrible yeast and have had fermentation problems with it before. if it doesn't get moving with the rousing & higher temp, i'd add more yeast. since you said time isn't an issue, i'd brew a smaller beer in the meantime then rack this onto the other beer's yeast cake.

Nobody has asked at what temp you mashed and are you sure your thermometer is calibrated, I agree there is a ton of less/un fermentable sugar in the grist and if you
Mashed to high you compounded the problem.

In addition, if you went from 52 a 1.051 it is still working and may just need more time to chew through those remaining sugars. Really big beers can take off quick and then really take their time getting those last points but I'm curious to know your mash temp.

its extract + specialty, there is no mash temp

dcp27 said:

its extract + specialty, there is no mash temp

Click to expand...

Got it, I was mobile and didn't read the recipe link that clearly

A lot of times dark extract may be made up of a lot of less fermentable sugars due to the nature of the extract. It is kind of in the same line as why extract brewers will get to 1.020 and not achieve any lower gravity, that plus the addition of a lb of lactose makes the higher FG a big possibility. I would still assume it move lower but may need the warmer temperature and more time with the rousing of the yeast. I would expect something the neighborhood of 1.030 +/-

Thanks for the feedback folks! Beersmith has the FG at 1.024, but I'm sure it can't take into effect the unfermentables in the extract. The spec sheet that Briess sent me says that the extract is 75% fermentable.

I've got a pale ale that I'm just about ready to bottle. Should I just rack this black bastard onto that yeast cake and see what happens?

I talked with the guy at my LHBS today, and he said he thought it'd really be a horse a piece, so I opted to spend $3.29 and buy another pack of S-04, which I came home and pitched. We'll see what happens the next few days...