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General Category => Yeast and Fermentation => Topic started by: ckujawa on March 28, 2013, 04:58:05 pm

Title: Stuck Fermentation
Post by: ckujawa on March 28, 2013, 04:58:05 pm
I have been having a problem with an IPA I have brewed. The first time I brewed the recipe my fermentation stuck at 1.035. I had several other issues with that batch and it wound up getting dumped. I made the recipe again and it turned out perfect. Mash time was right, efficiency was great, target O.G. was almost dead one (.003 off). This time I made some corrections in my fermentation. I bought a Fermtemp pad and maintained a 70-75 degree ferment temp. I bought an "aquarium style" pump and oxygenated the wort for about an hour before pitching. I even made a 2 cup yeast starter 3 days before pitching. Fermentation started a little slow but was steady for a week and after 7 days I went from 1.067 to 1.036. Airlock activity died down and I rechecked at 10 days and 1.035. Shock the carboy a bit to re oxidize and stir up settled yeast and I didn't get much reaction. I am supposed to switch to secondary and dry hop after 10 days but I don't see that  creating any more drop in S.G. Any ideas what could be causing this seemingly consistent problem. Last time I removed some slurry from bottom of the fermenter and pitched into a starter and the starter almost immediately exploded into fermentation (almost foamed over the flask within an hour of pitching) so I know that the yeast is alive and healthy. On the last batch I repitched the newly reactivated yeast into wort and nothing happened. Thanks for the help!!!!
Title: Re: Stuck Fermentation
Post by: euge on March 28, 2013, 05:05:51 pm
Recipe or grain bill? What were your mash temps if you went all grain or partial mash. Lastly, how does it taste?
Title: Re: Stuck Fermentation
Post by: jeffy on March 28, 2013, 05:18:06 pm
If you are using a refractometer instead of a hydrometer to measure your final gravity you will need to adjust the reading for the alcohol.  Using a calculator like this http://seanterrill.com/category/brewing/
I get a final corrected gravity for your beer of about 1.015.
Of course if you're using a hydrometer, then never mind.
Title: Re: Stuck Fermentation
Post by: quattlebaum on March 28, 2013, 05:28:02 pm
Need a little more info. What temp did ya mash at?  What yeast did ya use?  Specifics on how you measure your gravities. 2 cup starter isn't enough for that gravity
Title: Re: Stuck Fermentation
Post by: bonjour on March 28, 2013, 05:55:52 pm
If you are using a refractometer instead of a hydrometer to measure your final gravity you will need to adjust the reading for the alcohol.  Using a calculator like this http://seanterrill.com/category/brewing/
I get a final corrected gravity for your beer of about 1.015.
Of course if you're using a hydrometer, then never mind.
+1

1.016 was my rough initial estimate.
Title: Re: Stuck Fermentation
Post by: kramerog on March 28, 2013, 06:06:43 pm
A 2 cup yeast starter!  While that may not be the cause of your problem, 2 cup starter is probably worse than worthless.  Neve/Neva Parker of Wyeast (possibly White Labs) said at the 2012 NHC that 1 liter starters basically don't do anything (you trade off a little more yeast for yeast with less vitality).   I suspect that a 2-cup starter actually decreases the amount of viable yeast from a pitchable smack pack and reduces the vitality of the surviving yeast.
Title: Re: Stuck Fermentation
Post by: denny on March 28, 2013, 06:27:51 pm
A 2 cup yeast starter!  While that may not be the cause of your problem, 2 cup starter is probably worse than worthless.  Neve/Neva Parker of Wyeast (possibly White Labs) said at the 2012 NHC that 1 liter starters basically don't do anything (you trade off a little more yeast for yeast with less vitality).   I suspect that a 2-cup starter actually decreases the amount of viable yeast from a pitchable smack pack and reduces the vitality of the surviving yeast.

Neva/White Labs

And yep, I agree that a 2 cup starter is no better (likely worse) than no starter at all.
Title: Re: Stuck Fermentation
Post by: ckujawa on March 28, 2013, 09:54:15 pm
All grain batch (5 gallon) 13.5 lbs of grain 13 lbs of which is two row. I use a refractometer that I calibrated with distilled water but no other calibration or adjustments. Mashed at 154-55 degrees. I appreciate the brutal honesty  ;D I will make a larger starter next time. Doesnt the starter just speed up intial "kick off?" After a week the yeast should have done the same thing in the wort as it would in a starter flask??
Title: Re: Stuck Fermentation
Post by: kramerog on March 28, 2013, 10:10:19 pm
Underpitching with unhealthy yeast will likely cause various off-flavors (phenolics and acetaldehyde come to mind) and underattenuation (possibly high enough to be considered a stuck fermentation).   Don't feel bad; before the internet, I used to pitch 2 cup starters based on the recommendation of my LBHS.
Title: Re: Stuck Fermentation
Post by: svejk on March 28, 2013, 10:17:55 pm
As mentioned above, a refractometer reading will need to be adjusted after fermentation has started.  The reason is because the alcohol in the beer changes the reading.  In your case, if you are getting an unadjusted reading of 1.036 after fermentation, then when you make the adjustment it looks like your beer finished out at about 1.015-1.016 which seems reasonable considering your mash temperature.  If you would like to see a lower final gravity in your next batch, you could try mashing at 150F.

As far as yeast starters go, they serve several purposes with one of the primary purposes being to make sure that you are pitching enough yeast to do the job you are asking them to do.  When you underpitch a beer, you will still get some yeast growth, however the chances of getting a stuck fermentation or having other fermentation problems go up.  Since brewing is fairly labor intensive, you can look at the work of making a yeast starter as an insurance policy to make sure you are giving your beer the best chance at success.

One other consideration I didn't see mentioned is that your fermentation temperature of 70-75F seems to be on the high side for an IPA that would normally use Wyeast 1056 or another neutral strain.  For that style of beer, I really try to keep the temp out of the 70s if at all possible - especially early on in fermentation.
Title: Re: Stuck Fermentation
Post by: quattlebaum on March 28, 2013, 10:22:16 pm
I think you should ditch the refractometer and use a hydrometer. It's way more accurate if used right. Also pitch accordingly I use mrmalty.com  I bought a temp adjust refractometer and never use it because of its inaccurate nature. Seems any type of hop or grain debris screws it up.
Title: Re: Stuck Fermentation
Post by: ckujawa on March 28, 2013, 10:32:52 pm
So a refractometer is accurate at the time of mash and sparge? My O.G. reading is accurate but the further into fermentation the wort goes the inacuracy grows exponetially (due to alcohol in the wort)? Really appreciate all the help everyone has given.
Title: Re: Stuck Fermentation
Post by: jeffy on March 29, 2013, 12:24:56 am
So a refractometer is accurate at the time of mash and sparge? My O.G. reading is accurate but the further into fermentation the wort goes the inacuracy grows exponetially (due to alcohol in the wort)? Really appreciate all the help everyone has given.

Yes.  Use the calculator mentioned above.
Title: Re: Stuck Fermentation
Post by: donsmitty on March 29, 2013, 01:42:30 am
A 2 cup yeast starter!  While that may not be the cause of your problem, 2 cup starter is probably worse than worthless.  Neve/Neva Parker of Wyeast (possibly White Labs) said at the 2012 NHC that 1 liter starters basically don't do anything (you trade off a little more yeast for yeast with less vitality).   I suspect that a 2-cup starter actually decreases the amount of viable yeast from a pitchable smack pack and reduces the vitality of the surviving yeast.

Neva/White Labs

And yep, I agree that a 2 cup starter is no better (likely worse) than no starter at all.

So, if 2 cup starters are "worse than worthless" and 1 liter starters "basically don't do anything", what should a yeast starter be?  Is John Palmer wrong?  Is Brad Smith wrong?  Am I confused as a new home brewer?  Yes I am.  Help! 

I just went out to White Labs web site and found http://www.whitelabs.com/beer/homebrew/starter-tips.  Seems like they are contradicting themselves or their spokesperson.
Title: Re: Stuck Fermentation
Post by: kramerog on March 29, 2013, 05:23:05 pm
One size does not fit all when it comes to starters.  Here are some websites with calculators for starters: http://www.mrmalty.com/ (Jamil's calculator) and http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/ (Kai's calculator).  There are others. 
Title: Re: Stuck Fermentation
Post by: donsmitty on March 29, 2013, 05:28:30 pm
One size does not fit all when it comes to starters.  Here are some websites with calculators for starters: http://www.mrmalty.com/ (Jamil's calculator) and http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/ (Kai's calculator).  There are others.

Thanks for the links. 
Title: Re: Stuck Fermentation
Post by: drjones on March 29, 2013, 10:08:48 pm
Ckujawa - Once you get in the habit of using the refractometer on fermenting wort and running the numbers in a calculator to make the appropriate conversion, you'll be glad you have it.  I use the tool built into beersmith2 and it is very straightforward.  Different calculators use somewhat different functions to make the gravity conversion, so it is always an estimate, but I find the refractometer much more convenient than a hydrometer.  Also, they are significantly less fragile!