Fermentation question on an imperial stout

Discussion in 'Homebrewing' started by Scope4Beer, Nov 16, 2014.

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  1. Scope4Beer

    Scope4Beer Zealot (677) Sep 28, 2009 Pennsylvania
    Trader

    3 weeks ago I brewed an imperial stout with an OG of 1.111. I pitched WLP007 from an appropriate starter (based on MrMalty). Added yeast nutrient to the boil, aerated with a diffusion stone after pitching at 64F, and aerated a second time the next morning given the high gravity. It's been fermenting in my chest freezer at 63-65F, although the last 2 days the temps have dropped outside, leading to much lower ambient temps in my garage and ultimately the beer dropped to 61F yesterday and 59F today. I've let it sit for 3 weeks now and checked the gravity for the first time today. After correcting for temp and degassing the sample the SG is 1.041, for attenuation of only 63%. Was expecting it closer to 70-75% for a FG of 1.028. At this point I see my potential options as follows:

    1. Let it be. The sample tasted great FWIW. Other than me being a perfectionist and not hitting close to my planned FG, I could easily drink it. I was then planning on adding cacao nibs for a week before bottling and letting it condition for awhile.
    2. Warm it up towards 65-67F, swirl gently to resuspend the yeast, and check again in a few days to see what it's doing.
    3. Buy some more WLP007 and pitch it, after warming it up.
    4. I have a packet of dry Cooper's ale yeast in the fridge. I could pitch that too.

    Any suggestions or ideas? Thanks for the help.
     
  2. JackHorzempa

    JackHorzempa Grand Pooh-Bah (3,375) Dec 15, 2005 Pennsylvania
    Society Pooh-Bah

    My suggestion is option 2: let it warm up a bit and rouse. Check you gravity again in 1-2 weeks.

    Even if the gravity reading in 1-2 weeks is higher than 1.028 I would suggest you just package it as is.

    I recently homebrewed a clone of Hill Farmstead Everett (a Robust Porter). My OG was 1.084 (my personal target for this batch) and a final gravity of 1.033 (I was shooting for around 1.030). This beer is very, very tasty. My apparent attenuation is 59% for this batch.

    Cheers!
     
  3. FATC1TY

    FATC1TY Pooh-Bah (2,564) Feb 12, 2012 Georgia
    Pooh-Bah

    What was your mash temp?

    Beyond that, I'd warm it up anyways. Thats pretty cool for the yeast choice there, and it'll flocc out like a brick and give up.

    Give it some heat and see what happens. Otherwise you option is to use a more attenuative strain if you want to eek out some more points.
     
  4. Scope4Beer

    Scope4Beer Zealot (677) Sep 28, 2009 Pennsylvania
    Trader

    I mashed at 156F for 60 min. I do partial mash so only about half of my fermentables are from grain (6.5 lbs of grain and 4 lbs of DME for this one for a 3 gal batch).
     
  5. Scope4Beer

    Scope4Beer Zealot (677) Sep 28, 2009 Pennsylvania
    Trader

    That brings up another question. I know that higher mash temps will make for a sweeter and less fermentable wort. Are there any charts or equations that can help predict attenuation based on mash temp?
     
  6. VikeMan

    VikeMan Grand Pooh-Bah (3,067) Jul 12, 2009 Pennsylvania
    Pooh-Bah

    Both Greg Doss and Kai Troester have published data on this. And BrewCipher takes it into account when predicting attenuation.
     
  7. Scope4Beer

    Scope4Beer Zealot (677) Sep 28, 2009 Pennsylvania
    Trader

    Thanks!
     
  8. HarleyRider

    HarleyRider Initiate (0) Aug 22, 2007 Connecticut

    I would add a teaspoon of yeast nutrition and stir it in as well as kick it up 2 degrees to jump start it back up.

    Then check Gravity in a week to see how it's doing.
     
  9. sjverla

    sjverla Initiate (0) Dec 1, 2008 Massachusetts

    I was actually just wondering about this. I brewed a Double IPA this weekend and forgot to add yeast nutrient at the end of the boil since I'm not in the habit of it. It's taken it's sweet time to get started, but after 42ish hours I'm starting to see thin krausens forming on both. I was surprised to see it take so long because I divided the 1.080 wort into 2.5 gal batches, and each got a full packet of rehydrated US-05.

    At this point I'm inclined to let it ride and take a sample it two weeks, but was debating adding nutrient after the fact. Is that something you have experience with?
     
  10. Scope4Beer

    Scope4Beer Zealot (677) Sep 28, 2009 Pennsylvania
    Trader

    I've got a question about bottle conditioning this beer now. Thanks to @VikeMan and his BrewCipher, it looks like my predicted FG should be 1.034. I checked the gravity again last night after 3 days and it went down a point to 1.040 after it's been at 68F and swirled a few times to rouse the yeast. I obviously won't bottle until the OG is stable a few days. Assuming it stays put where it is now and I bottle, I was intending on adding Lallemand's CBC-1 dry yeast for bottle conditioning/carbing to ensure it carbs properly. The technical data on CBC-1 says it does not use maltotriose. Would I therefore not have to worry about it fermenting any residual sugars left in the beer and leading to potential overcarbing or worse yet bottle bombs? Would I be safer utilizing champagne yeast for conditioning? Or would I not have to worry about it at all since it's that close to predicted FG? Thanks again.
     
  11. VikeMan

    VikeMan Grand Pooh-Bah (3,067) Jul 12, 2009 Pennsylvania
    Pooh-Bah

    Neither CBC-1 nor Champagne strains use maltotriose. But... does CBC-1 eat maltose? I'm not sure, but AFAIK it does. How well it does, I dunno. Champagne yeasts strains, OTOH, are pretty bad at eating maltose. If you don't get a more definitive answer, I'd be inclined to go the champagne yeast route.
     
  12. JackHorzempa

    JackHorzempa Grand Pooh-Bah (3,375) Dec 15, 2005 Pennsylvania
    Society Pooh-Bah

    On a related matter, I found the below review for CBC-1 yeast on amazon:

    Excellent yeast for bottle conditioning.

    By David Siegfried on March 20, 2014

    Verified Purchase

    I am a home brewer. This yeast is specially formulated to be added to your beer during bottling. Adding fresh yeast along with your priming sugar just prior to bottling ensures a faster and more complete bottle fermentation so you can start enjoying your carbonated brew within a week rather than the 3-4 weeks it often takes when relying on the old yeast that is still present after the main fermentation is complete.

    Re-Inoculation rate is as follows:

    1.9g yeast per 5 gallon batch. This is about 1/2 teaspoon. For smaller batches it's about 1/10 teaspoon per gallon, or the volume of one drop per bottle.
    Or you normally pitch one 11g packet in a 5 gallon batch, you can figure pitching roughly 15% of that for the re-inoculation.

    Hydrate the yeast in a little lukewarm water prior to pitching it in your bottling bucket. Mix this slurry into your priming sugar solution in the bottling bucket, and then rack your beer on top of that. Bottle and condition as usual.

    The yeast exhibits high flocculation and forms a tight mat at the bottom of the bottle after completion of conditioning. It's neutral in taste so it doesn't affect the flavor of your beer.

    Great stuff, highly recommended.”


    Cheers!
     
  13. Scope4Beer

    Scope4Beer Zealot (677) Sep 28, 2009 Pennsylvania
    Trader

    Reading the general description again and not the technical specs and it says it can be used for primary fermentation, so I guess it would use maltose. I'll go with the champagne yeast to be safe. Thanks!
     
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