Stuck fermentation - Doppelbock

Ingredients
1

I think I have a stuck fermentation, and am requesting some assistance/advice.

On January 18, I brewed a Doppelbock with an O.G. of 1.083.  The mash temp did not get above 150 degrees F, and mainly stayed between 149 degrees and 144 degrees.  Mash was single infusion with charcoal filtered water, no added minerals; see the grain bill below.  I chilled the wort to approximately 62 degrees, and pitched a 1000ml starter that fermented for 2 days on a stir plate, included a wort fortification after the 1st day, yeast nutrient, and with one vial of White Labs Zurich Lager Platinum Strain.  The starter showed signs of a very vigorous fermentation, as it almost blew the foam stopper off.  A week later, the gravity was at 1.050, and I racked to secondary, but gently swirled the yeast on the bottom while racking.  I made another starter with two more vials of WL Zurich Lager yeast and let it go for 24 hours, then pitched and re-aerated; that was 5 days ago.  I planned to extend the secondary another 6 days (which ends tomorrow (2/4/15).  Today, I checked and the gravity is at 1.040.  The diacetyl rest is set to kick off tomorrow afternoon (I have a programmed BrewBit controller) - diacetyl rest is set for 72 degrees F for 3 days.  I have been fermenting the primary and secondary at 58.5 degrees F.  Please help.

Grain Bill, ~75% brewhouse efficiency:
9.5 lbs Munich Malt
9.0 lbs Belgian Pilsner Malt
0.75 lb Caramunich Malt
6 oz Carafa II Dehusked Malt
5.5 oz Aromatic Malt

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You underpitched in the beginning, which could have caused a big lag.  An appropriate sized starter for this big of a beer might have been 3-4 liters and you only used 1 liter.

That being said, your re-pitch with more yeast was a good idea and probably helped.  And your planned diacetyl rest will also help finish up the fermentation.  However I would delay the D rest for another 4-5 days – it is a little early to be doing that right now.

Also… I wouldn’t have racked.  Leave the beer in primary (or secondary now) until it is finished.  You don’t need to rack it at all unless leaving it on a yeast cake for >10 weeks in my experience.  Risk of autolysis is virtually zero until that point.

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“A week later, the gravity was at 1.050, and I racked to secondary, but gently swirled the yeast on the bottom while racking.”  <<<< why did you rack so soon?

beside that, as mentioned i’d have pitched 4-5 times size starter than you did. I also prefer colder pitch and lower temps…46-48F pitch and 50-52F fermentation. your temps now are almost at the temp i hold for d-rest…62F.

hope it works out for you, though.

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All of this^^^^^

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You would have had a better chance of fully attenuating your wort if you had pitched the starter at high krausen and not racked too early.  However, what you do from this point will determine if you produce something drinkable.

First off, let the yeast do its job before performing a diacetyl rest. It may take weeks for the yeast cells that are still in suspension culture to fully attenuate the wort.  However, if fermentation sticks again, here’s what you need to do to salvage the batch.  Drive to your LBHS and purchase four packs of Danstar W-34/70.  Rehydrate the yeast in 400 to 500ml of boiled and cooled to room temperature water.  That’s not the ideal rehydration temperature, but it will lessen the shock the rehydrated culture experiences when you pitch it. Dry yeast is propagated aerobically; therefore, it does not require aeration of the wort.  If dry W-34/70 does not do the trick, it is time to enlist the aid of the Terminator; namely, K1V-1116.  K1V-1116 is an alcohol-tolerant wine yeast that can ferment maltotriose.  It’s my “Hail Mary” strain.

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Thanks for the advice everyone!  I usually pitch a 2000ml starter with 2-4 vials of yeast, but I discovered too late that I only had one vial of that Platinum Strain on hand.  That’s why I did the starter for two days with a fortification.  Didn’t work.  As for racking too early, I had a feeling that I shouldn’t have done that, but did anyway as it is my usual practice to rack to secondary after a week; I am not used to brewing high gravity beers, even though I have been brewing for 14 years.  Lesson learned.  Again, thank you!

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Indeed you do!

[quote author=hobbsta]I chilled the wort to approximately 62 degrees, and pitched a 1000ml starter that fermented for 2 days on a stir plate, included a wort fortification after the 1st day, yeast nutrient, and with one vial of White Labs Zurich Lager Platinum Strain.
[/quote]

According to any calculator, you underpitched by a metric crap ton. Using JZ’s calculator, you underpitched by 10 fold. According to Kai, you underpitched by 4 fold. Use this calculator next time to get off on a better foot: http://yeastcalculator.com/

[quote author=hobbsta]A week later, the gravity was at 1.050, and I racked to secondary
[/quote]

Don’t rack the beer if it isn’t at the terminal gravity!

[quote author=hobbsta]I made another starter with two more vials of WL Zurich Lager yeast and let it go for 24 hours, then pitched and re-aerated; that was 5 days ago.
[/quote]

This was a good move! Now leave it there.

[quote author=hobbsta]I planned to extend the secondary another 6 days (which ends tomorrow (2/4/15).  Today, I checked and the gravity is at 1.040.
[/quote]

Leave it in the vessel it is in until you reach terminal gravity.

[quote author=hobbsta]The diacetyl rest is set to kick off tomorrow afternoon (I have a programmed BrewBit controller) - diacetyl rest is set for 72 degrees F for 3 days.
[/quote]

You should know that beer/yeast are not on your timetable. You must follow the yeast’s timetable. If I were you, I’d be raising the temp to encourage what little yeast you have in there to actually finish up, but I wouldn’t dare rack it until it reaches terminal gravity (if it ever does).

Here’s a quick run down of what you can do next time:

  1. Chill to below 50F.
  2. Pitch at below 50F and then let it warm to 50-52F.
  3. Oh yeah, pitch a LOT of yeast. Follow online calculators if need be.
  4. Don’t transfer it.
  5. Check gravity before doing anything.
  6. Raise temp a bit if you’re past 50% terminal gravity, but don’t rack it.
  7. Raise to a d-rest (62F) if it needs it.
    8 ) Now you should be at terminal gravity.

Hope that helps!

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Thanks much, Amanda!  Somewhere along the line, I learned to ferment lagers at 58 degrees F, and diacetyl rest at 70-72.  By your recommendations, I have been incorrect, but lucky (I guess).  All my other lagers have come out nicely, except the higher gravity ones.  I will use your method from now on.  :slight_smile:

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While higher than normal, 58F is not completely out of the question if the lager yeast strain being employed is a Frohberg strain.  Frohberg strains often perform better between 55F and 60F than they do between 45F and 54F because they are tetraploids (4 sets of chromosomes) that contain two sets of Saccharomyces eubayanus (S. eubayanus) chromosomes and two sets of Saccharomyces cerevisiae (S. cerevisiae) chromosomes.  In essence, Frohberg strains are genetically 50% ale yeast (W-34/70 is a confirmed tetraploid Frohberg strain).

Saaz yeast strains are more cold tolerant than Frohberg strains because they are triploids (3 sets of chromosomes) that contain two sets of S. eubayanus chromosomes and one set of S. cerevisiae chromosomes.  The S. eubayanus genetic contribution is what gives the Saaz and Frohberg Saccharomyces pastorianus strains their cold tolerance. Saaz yeast strains are 2/3rds S. eubayanus; hence, they are more cold tolerant than Frohberg strains.

With that said, I am currently fermenting what I am referring to as American Pale Bock at 57F with  Wallerstein Saaz Yeast #64B.  While there was a low amount of fruity outgassing in the early stages of fermentation, that odor has been replaced by low-medium H2S.  I am curious to see how this batch turns out given the fermentation temperature and the fact that the scientist who propagated the strain for me believed that it may be a petite selection.  I thought the same while propagating it on solid and in liquid media.  However, I am not so certain now that I have seen it in action in a real world wort.

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Tangent: American Pale Bock has piqued my interest. Care to share a recipe?

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It’s nothing special.  I brewed a batch of old East Coast-style lager for which I under-calculated the extraction rate that I would get with Rahr 2-Row.  This batch was my first experience with Rahr 2-Row. Many people mentioned that they experienced lower extraction rates with Rahr 2-Row than they did with Briess 2-Row, so I based the recipe on a lower extraction rate.  Instead of obtaining a firm Classic American Lager, my O.G. landed squarely in the pale bock range; hence, the name American Pale Bock.

The grist was 87.5% domestic 2-row/12.5% flaked maize.  Sterling was used for kettle and finish hopping.  I had originally planned to use Cluster for the kettle hop, but I had to break down and vacuum seal a pound of 2014 Hops Direct whole Sterling while brewing; therefore, I had no desire to break open and repackage one of the 4oz packages of 2014 Hops Direct whole Cluster that I packaged when I brewed an all-Cluster IPA a couple of months ago.  Plus, I like the way that old East Coast-style lager recipes turn out when hopped with the American cultivars that were derived from the land race nobles. Old East Coast-style lager is a great style with which to experiment with hops such as Crystal, Liberty, Mt. Hood, Ultra, Santium, and Sterling.  These cultivars tend to have exaggerated noble characteristics, especially Liberty.  Liberty is my all-time favorite domestic malt/maize lager hop.  A pale malt/maize grist makes Liberty pop.

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Just read this thread and have to say - what an awesome forum we have! Compared to some others, the info here is stellar.

Pitch big
Pitch low
Don’t rack till done
Keep recipes simple but feel free to experiment

All fantastic ideas!

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Mark- are you saying there’s nothing to be gained from oxygenating wort when pitching dry yeast? if so, are there any negatives if you do?

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I’ve heard this suggested for a long time and is one of the reasons why I suggest dry yeast to new brewers, because aeration is not as critical. That said, I always aerate “just to be sure”.

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While it will not hurt, aeration is not as critical with dry yeast as it is with liquid yeast because dry yeast is propagated aerobically; hence, dry yeast cells never go through a period of ergosterol and unsaturated fatty acid (UFA) depletion like their batch grown liquid counterparts.  The purpose of aerating wort is to allow yeast cells to rebuild their ergosterol and UFA stores in preparation for budding and fermentation.

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Hi Mark,

Could you share the literature references where I could get detailed info regarding the dry yeast aerobic propagation? I’ve read articles about it… but not so ‘scientific’ ones, and I’d like to read more about it (in Brazil we use a lot of dry yeast)… this is a subject I really enjoy.

When you say they propagate aerobically, you mean they maintain sugar levels down enough to avoid the crabtree effect?

I thought dry yeast had high levels of sterols and UFA (as well as trehalose) just because how they cold condition the yeast before lyophilization, since it would stimulate a pre-hibernation behavior (which would get the sterols and UFA reserves up).

Thanks,

Guenther

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You will not find many research publications that apply specifically to brewer’s yeast.  However, you will will find a plethora of publications that apply to the Saccharomyces cerevisiae species.  You just need to use the search terms “chemostat,” “aerobic,” “Crabtree,” and “saccharomyces.”  You will have to weed through a lot of chaff to find the wheat.

Yes

No, cold conditioning has nothing to do with it.  High levels of sterols and UFAs are the result of propagation via respiration (i.e., aerobic propagation).  Sterols and UFAs are synthesized in the respirative metabolic pathway.

While the paper linked below compares lipid compositional differences between aerobically and anaerobically propagated yeast, the author answers your question in the introductory paragraph.

http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1982.tb04123.x/pdf

“Aerobically grown yeast cells contain sterols and unsaturated fatty acids in excess amounts. When aerobic pitching yeast is used, aeration of wort is of no advantage, because no more sterols and unsaturated fatty acids are synthesized by enriched yeast cells.”

Additionally, unlike dried yeast that is propagated in a lab, industrially produced dry yeast is not dried in a lyophilizer.  It is dried using the same technology that is used for drying active baker’s yeast; namely,  fluidized-bed dryers.