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-   -   stuck fermentation high gravity ale (http://www.homebrewtalk.com/f163/stuck-fermentation-high-gravity-ale-250833/)

oneofthefew82 06-12-2011 02:19 PM

stuck fermentation high gravity ale
 
I started an ale with OG of 1.131 with an ~2L starter using Wyeast 4347 Eau de Vie. I can post the original recipe if needed. but after 3 weeks in the primary, the gravity has only fallen to 1.071 and has stuck there since week 2. The yeast should be able to handle up to 21% abv and its only at 8.3%. It does have a low flocculation rate. And I have been keeping the temp between 65 and 70F, basic room temperature. So what would be the best way to restart the fermentation? Should I prepare a new starter using the 2L WLP099 H.G ale yeast? I originally planned on using it but had to settle for the Wyeast. My aeration wasn't the best either.

Nateo 06-12-2011 06:22 PM

I'd say you pitched way too few yeast. I probably would've done at least 6L total worth of starter, going pack > 2L, then split that up into 3 or 4 more 2L starters.

Osmotic pressure begins to be an issue for yeast over 1.120. Instead of starting out with all the fermentables at once, it'd be better to stagger them, letting the yeast work through the sugars at a lower gravity, and then adding sugar while fermentation is under way.

Low flocculation should keep the yeast in suspension longer, which would help the attenuation, not hurt it, so that's not the issue.

Also, as the gravity increases, oxygen solubility decreases. So even great aeration with pure O2 at that high of a gravity will result in poor oxygenation. For high gravity beer, White and Zainasheff recommend using pure O2, and then re-oxygenating after about 12 hours, to allow the yeast to grow and split once before they get more O2.

Pitching a 2L starter of a high gravity yeast won't really help you. The issue is the yeast count and health, not the alcohol tolerance. Pitch a very large starter of yeast. A whole yeast cake would be best, but I'd do at least a stepped-up starter, equialent to 8L. You want to step up the starter, because yeast are healthier and you get a bigger yield per inoculation rate with smaller starters, like 1.5-2L.

oneofthefew82 06-13-2011 10:29 AM

ok so just make another 2L starter or two of the same yeast and add it?

Nateo 06-13-2011 11:29 AM

Quote:

Originally Posted by Nateo (Post 2999927)
I'd do at least a stepped-up starter, equialent to 8L. You want to step up the starter, because yeast are healthier and you get a bigger yield per inoculation rate with smaller starters, like 1.5-2L.

You're pitching into an ongoing fermentation. Whatever O2 you were able to get into suspension is gone now, so your yeast won't be able to reproduce well, if at all. Unless you can oxygenate with pure O2, your starter should be big enough that the yeast don't need to reproduce at all. I'd do another 2L starter, chill, decant, divide that into 4 parts, and do 4 more 2L starters, then when those are all at high krausen, pitch them into the wort.

dcp27 06-14-2011 03:38 PM

what temp did you mash at? im pretty sure that yeast is mainly supposed to be used with simple sugars and has difficulty with the more complex sugars found from extracts & grains. a nice big well aerated starter of WLP099 (or split up like nateo said) would get the job done. Chico (Wyeast 1056/WLP001/S-05) and several belgian strains could also do the job as well, so it depends what characteristics you want out of your yeast.

oneofthefew82 06-14-2011 10:58 PM

I mashed at 150F or so for 40 minutes with 3.5lb grain, the rest was 16lb extract. but its a stout so I am just looking for low ester formation and to dry it out with the yeast to get it to 14% abv. So I was just looking for neutral yeast basically.

dcp27 06-14-2011 11:23 PM

I'd make a highly aerated 1-2gallon starter of WLP001/Wyeast 1056 then and pitch it at high krausen with some yeast nutrient. it can handle up to 15%.

just to be sure, that FG was with a hydrometer not refractometer right?

check this out for calculating starter size in the future: http://www.mrmalty.com/calc/calc.html

otisbrad 02-11-2012 07:46 PM

what difference would it make if you are using a refractometer - it won't measure as well post fermentation ?
I have a similar problem on a Hair of the Dog Adam clone - started 1.105
finished 1.055 - added a 2 L starter of champagne yeast
had a flimsey fermentation down to 1.050
all using my refractometer

Nateo 02-11-2012 08:08 PM

Quote:

Originally Posted by otisbrad (Post 3773911)
what difference would it make if you are using a refractometer - it won't measure as well post fermentation ?
I have a similar problem on a Hair of the Dog Adam clone - started 1.105
finished 1.055 - added a 2 L starter of champagne yeast
had a flimsey fermentation down to 1.050
all using my refractometer

Chapagne yeast won't work. Almost all wine yeasts cannot metabolize maltotriose, and most don't metabolize maltose very well either. Maltotriose is a trisaccharide and composes about 13% of the fermentable sugars. Maltose makes up about 44% of the fermentable sugars.

Yeast tend to eat the simple sugar first, then moves on to the more complex sugars. If your gravity is too high because of excess fermentable sugars, it's not likely that they're simple sugars. Residual fermentables are most likely maltotriose, which your champagne yeast won't be able to eat.

A better course would be to pitch onto a yeast cake from another beer, or a very large, very active starter.

Here's some further reading:
http://hbd.org/brewery/library/EnzStuckFermAW1095.html

Danateahan 01-14-2013 09:44 AM

Quote:

Originally Posted by otisbrad (Post 3773911)
what difference would it make if you are using a refractometer - it won't measure as well post fermentation ?
I have a similar problem on a Hair of the Dog Adam clone - started 1.105
finished 1.055 - added a 2 L starter of champagne yeast
had a flimsey fermentation down to 1.050
all using my refractometer

Refractometers are really only useful up until half way through primary fermentation.

Use a hydrometer to measure fermentation properly. If you don't you will falsely think your beer hasn't attenuated properly or stalled in fermentation when in fact alcohol will skew a refractometer reading.

There are tools to help try and compensate using a refractometer but I have found it useful to measure general progress using a refractometer until primary fermentation is complete (saving wasting beer) then I get an accurate reading using a hydrometer.

You would be amazed but your 1.050 beer is actually probably more like 1.020 when measured properly (bang on what you would probably expect). 1.050 would be very sweet (think of how sweet wort is before boiling fermentation on. 1.050 beer - I'm sure your beer didn't taste that sweet)


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