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-   -   Imperial Pilsener - is fermentation stuck? (http://www.homebrewtalk.com/f39/imperial-pilsener-fermentation-stuck-356440/)

asalisbury 09-24-2012 01:44 PM

Imperial Pilsener - is fermentation stuck?
My 5 gallon batch of imperial pilsener is now two weeks into primary. Temp is being held at ~47 degrees F. The OG was ~1.089. I used Bohemian lager yeast (Wyeast 2024) in a starter to get ~250 billion viable cells. (I know I under-pitched because ~400 billion cells are recommended.) I'm not sure how significant it is, but I also made the error of fermenting the starter in high temps between 65 and 78 degrees F. :cross:

I just checked the FG and I am concerned that fermentation might be stuck. It is very high: ~1.040. Maybe I should give it another week or two before being concerned? Yesterday I sat and watched the airlock, and it appeared to release a bubble about once per minute, if that tells you anything.

So my question is, should I pitch more yeast? If so, in cases of pitching later on into the fermentation, how does one strike a balance between the issue of oxidation, with the requirement for aeration for the newly-added yeast?

Let me know if you need any additional info. I've been keeping pretty detailed notes. Thanks!

Pie_Man 09-24-2012 03:45 PM

In my experience, fermentation is mostly done by two weeks. Waiting another week shouldn't hurt anything, but I doin't think you'll get much more attenuation.

I don't really know how one would strike a balance between aerating the beer for the new yeast and oxidizing the beer you already have. The one time I had a stuck sparge, I simply added new yeast without aeration. With the yeast I used, I was able to get close to my desired FG and the beer came out pretty good. It was a high gravity barley wine, so that style is probably more forgiving than your imperial pilsner.

Have you tasted this yet? I'd let the taste guide your decision.

TopherM 09-24-2012 05:03 PM

You should expect this one to end at around 1.022, so you are definitely high on the FG.

You could very well have a stuck fermentation. The underpitching coupled with the high ABV can and will overwork the yeast pretty easily. Definitely give it some more time, though. My last lager fermentation took about 18 days to get to 75% of expected OG before my D-Rest. Since you are at 1.04, the most active part of ferementation is definitely complete, and you could go ahead and take this one out of the 47F chamber and let it finish up at room temp, or jack the temperature controller up to about 65F. Give it a few days at that temp and take another reading. If it's moving, let it go and you'll be fine. If you are still at 1.04, you may need to re-pitch, though you might be better off pitching some S-05, Nottingham, or other neutral yeast instead of the same one you used before.

As an imperial, you might actually enjoy the residual malt sweetness of a 1.04 FG beer, so give it a taste and see what you think. Your ABV won't be as high, but it will still be up there and the maltier backbone might cover it better.

So you have lots of options!!

Good luck!

asalisbury 09-26-2012 12:56 AM

Hey guys -- thanks for the advice. BTW, great to see other nearby-Floridians on here.

I'm heeding both of y'all's advice and tasting it...

OK, here goes...*sip*...

Eh, not bad, but definitely too sweet and body is too full. I think it needs to attenuate at least to 1.022 if not even slightly more. TopherM, I agree with you about a malt sweetness potentially being a plus, but in this case, even after dry-hopping and hop-tea-priming, I'm thinking the sweetness will be too cloying. It tastes like half-pils and half-unfermented wort. I'm going to risk it and just pitch another slap pack of Bohemian Lager (2124) and maybe just give it a lil stir. I'll also step the temps up a little (maybe like 55 degrees F?) for another week or so. After that, I'll see how it's progressed, and if good, then D-rest and lager. Does that sound okay?

Pie_Man 09-26-2012 01:35 AM

Sounds like a plan, good luck. I figured it would taste thick and cloying, but it's a good idea to taste it first, especially since you're already taking a gravity reading. I don't know that yeast strain, so I can't comment on the fermentation temperature.

Your end product might not be what you expected, but it should turn out a lot better than what you tasted today.

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