Question On Fermentation Progress

[FastEddie]

I recently brewed a double Black Butte Porter clone which had a O.G. of 1.107 (projected to be 1.109). I took a reading at 7 days which was 1.035, a significant progress. I again took a reading at 14 days (after racking off of the trub into a conditioning carboy) which was 1.034. The projected F.G. is 1.025. I'll take a reading at 21 days to see what the progression is like. The ambient temp of the beer has been relatively unchanged at 68-70*F the entire time. The yeast strain is WLP002 - English Ale which was pitched as a 1L starter (much lower than a proper pitching ratio I realize). If the gravity does not change, or changes by only .001 or .002, would it hurt to pitch some more yeast, or is yeast population likely not the problem? Two things stand out for me: 1) The fermentation temp is on the higher side of the range of the yeast, but still within the range. 2) Calculating the %ABV based on the O.G. and current gravity readings puts the beer at close to 10% which is the upper limit of the yeast according to White Labs. If the high degree of alcohol is the cause of the failure of the yeast to complete fermentation, pitching the same yeast strain seems silly. I guess I could pitch a higher alcohol tolerant yeast but am weary to do so as I don't want to alter the flavor of the beer. I have absolutely no problem with waiting for the beer to finish, however long that may be, but I want to make sure that fermentation is still happening, and if not, take steps to correct the stall. I realize that .001 is still a change, but I could have taken a reading three days in a row and come up with the same reading which would have indicated completion of fermentation, yes? Just looking for some suggestions. Thanks.

 

[hercher]

If the alcohol is killing the yeast, I think you may have to add a different, more alcohol tolerant yeast. But before you do that, try rousing the yeast by gently agitating the beer to get it in suspension. If that doesn't help, if you have more of the same yeast, try pitching some of that (I would make a small starter). With such a big beer, underpitching could be part of the problem.

If these don't work, try a wine yeast. Of course, before doing that, taste the beer. Maybe you don't need to do anything!

 

[Bsquared]

How dose it taste? you might have a lot of unfermentables in there and this is as low as its going to go.If its too sweet than its got some time to go. Things get tough for yeast when the EtOH level gets high, but they can work through it, it just takes time and a lot of yeast. as long as you are not above 12-14% most the yeast should still be alive.

I think there is a lot of debate of this and other people might disagree, but next time let the beer sit on the primary yeast cake until fermentation has stopped , and the gravity reading is stable for at least a week.

One thing you can try doing now is top crop some yeast from your fermenter, and make a 500ml starter with them, and add them back in.

One other thing is WLP007 English dry ale yeast might have been a good alternative yeast to use, but if 002 was at the right pitching rate and given enough time I bet it could have gotten the job done.

good luck.

 

[FastEddie]

Thanks for the suggestions, I'm sure it will be fine. It tasted pretty damn good for 2 week old beer, not sweet at all. It's got some additions and aging/scrubbing to yet to go, I'll be curious if the gravity changes much in the next couple weeks. I guess the only thing I might be concerned about is if the ABV has affected the yeast, then bottle conditioning might be slowed or not possible. Any last thoughts on that? Would it be worth pulling a small sample and adding some dextrose to it to see if the yeast pick it up? Thanks again.

 

[oswegan]

I recently brewed a double Black Butte Porter clone which had a O.G. of 1.107 (projected to be 1.109).

Double Yum.