Stubbornly Lazy Yeast

[Stags]

First off, I can smell the hate coming, so feel free to flame away, but yes I have googled this forum and others to exhaustion. With that said, I’d love to get the insight of those more experienced than me.

Problem: in spite of great pains taken to keep the yeast happy, since the weather has cooled, ferments are dragging into 4 weeks. I feel like that’s not normal and want to correct that. I’m scratching my head as to what I may be doing wrong. I am hoping some expert scrutiny of my processes and controls may yield better solutions.

I run 2 continuous ferments- one UJSSM about 40 gallons in a 55 gallon drum and 20 gallons of panela rum in a 30 gallon drum. Both fermentations use ~25% backset/ dunder. Yeasties involved are WLP099 (high gravity ale yeast) for UJSSM and WLP521 Hornindal Kveik for the rum. Water source is tap run through a charcoal RV filter.

I have bent over backwards to ensure the yeast involved are pampered. And I mean pampered. Both fermenters are insulated and individually climate controlled with warming mats calibrated to the midpoint of the yeasts happy zone (67° and 90° respectively). I’ve ordered additional supplies to add warming mats and insulation to the bottom of the fermenters when I’m able to unload them next (hard to do with 300+lbs of water involved). Even without that, instant read of wash temp is always within 1-2° of the thermostat reading. Both live in my insulated garage with a thermostat driven space heater keeping ambient temp at around 60°.

Both have more than adequate nutes- they’ve gotten double the recommended amount of white labs yeast nutes plus dead yeast, epsom salts, DAP, etc. My understanding is that these strains are rather hangry, hence the dosages.

Both have oyster shells buffering PH to about 5.

After all of that the panela seems vigorous but slow, the UJSSM seems nearly stalled at about 1.012.

I feel as if the only remaining deficiency I could have is dissolved oxygen. I had previously been under the assumption that using a drain for backset and a hose from a height to fill the fermenter- plus vigorous stirring in intermediate vessels to dissolve sugars- would add enough oxygen to allow the yeast to multiply. I’ve already ordered an aquarium aerator for future batches (thanks cyber Monday) but will try adding olive oil to these in process ferments to see if that kicks things up.

So I kick it to the masters- what might I be missing?

[Sporacle]

Why do you feel hate coming? Anyway I have found with my UJ that my ferments began to slow with each generation over time. Probably noticed it around gen 4 and 5, these also took longer to start. To combat this I reduced my backset amount to around or a bit over 10%.
I didn't really notice a change in flavour profile ( but I do drink it white and early)
I don't know what my pH was as I don't measure it, I just know that the reduction in backset improved my ferment times
God luck

[Stags]

Why do you feel hate coming? Anyway I have found with my UJ that my ferments began to slow with each generation over time. Probably noticed it around gen 4 and 5, these also took longer to start. To combat this I reduced my backset amount to around or a bit over 10%.
I didn't really notice a change in flavour profile ( but I do drink it white and early)
I don't know what my pH was as I don't measure it, I just know that the reduction in backset improved my ferment times
God luck

I guess I’ve been accustomed to guys getting flamed I expect to see it happen on every thread *insert the “I’m in danger” meme here*

I remember reading in the UJ sticky about guys reducing backset but it seemed like that was typically due to ph drop and they countered that with shells? That said will try this on the next batch for science.

[greggn]

- what might I be missing?

Doing a pre-coffee read, I see nothing glaringly wrong. I have no experience with those yeasts so I have nothing to offer regarding their care and feeding.

I would suggest running a small test batch, using the same protocol, but with baker's yeast. If that fails, given the forgiving nature and wide tolerance of baker's yeast, then there is indeed something fundamentally wrong.

[Stags]

[quote=greggn post_id=7769144 time=1701180584 user_id=53365]
[quote=Stags post_id=7769103 time=1701125085 user_id=92554]

- what might I be missing?
[/quote]


Doing a pre-coffee read, I see nothing glaringly wrong. I have no experience with those yeasts so I have nothing to offer regarding their care and feeding.

I would suggest running a small test batch, using the same protocol, but with baker's yeast. If that fails, given the forgiving nature and wide tolerance of baker's yeast, then there is indeed something fundamentally wrong.
[/quote]

So I may have gotten a little tipsy last night and made a giant starter of DADY and bakers to add to the UJSM to see if I could give it a “jump start” since I have the yeast on hand, it’s cheap, and I’ve been so annoyed by the fermentation time I’m planning to kill that cake and replace it with something else after this batch anyways.

Another question for the crowd-

Is it possible that fermentation is complete and I’ve done something else that is causing a falsely high SG reading? E.g suspended calcium bicarbonate? By my taste test that UJ ferment is bitter and dry. Maybe maybe maybe the faintest most remote hint of sugars remaining, but the primary flavor is very bitter and very dry. Like hyper concentrated grapefruit juice bitter.

[subbrew]

All I can think is you are building up some waste product the yeast doesn't like with the 25% backset. I personally never go above 20% and for something like UJSSM where it goes generation after generation it is closer to 10 or 15%

Not sure how many generations you are in but the yeast may not be what you originally pitched. Particularly on the UJSSM where you are adding raw grain, you are also adding wild yeast. It is possible a wild yeast has supplanted the WLP099. Sounds like you already pitched other yeast. I would also try bumping up the temp from your 67 to 80 or so.

[Stags]

I’m wondering if the anti foam I’ve been using could make its way into the wash via backset and hurt the yeast? Fermcap s is what I’ve been using.

Cranked heat to 85, it’s made it to about 80, things do seem to be picking up. I’m on gen 8 for the UJ so yes something may have built up.

I thought the legal minimum for sour mash was 25% backset- curious how the commercial guys address that.

[subbrew]

Although not backset, with UJSSM you are also getting the soured mash that remains in the grain. So besides the 25% backset you also had some % of leftover sour wash.

[Stags]

Although not backset, with UJSSM you are also getting the soured mash that remains in the grain. So besides the 25% backset you also had some % of leftover sour wash.

Well played sir. I’d postulate that grain bed is probably 25% on its own

[bilgriss]

To address the question of dissolved oxygen - Yeast need oxygen to reproduce and increase their numbers, but not to ferment your wash. If you start with a healthy ferment and have plenty of yeast but it slows down, that's unlikely to be related to a lack of oxygen.

[Saltbush Bill]

My guess is to much backset to. Next ferment use no back set at all......just your old grain, see what happens.
After that if fermentation has sped back up start using backset again.......but less of it.
Old distiller told me, slow ferment , less backset or dunder, If ferment is faster than you want add more backset or dunder.
Its always worked that way for me, I gave up counting at about 70 gens.

[Stags]

My guess is to much backset to. Next ferment use no back set at all......just your old grain, see what happens.
After that if fermentation has sped back up start using backset again.......but less of it.
Old distiller told me, slow ferment , less backset or dunder, If ferment is faster than you want add more backset or dunder.
Its always worked that way for me, I gave up counting at about 70 gens.

Great feedback thank you sir. Reading that I’m starting to see the dunder/ backset as a throttle rather than an ingredient so that’s a change in perspective

[shadylane]

First off, I can smell the hate coming, so feel free to flame away,

Stubbornly Lazy Yeast, I don't like the sound of that.
I'll have you know, trillions of yeast are my friend and I've never known one to be stubbornly lazy.


Both have more than adequate nutes- they’ve gotten double the recommended amount of white labs yeast nutes plus dead yeast, epsom salts, DAP, etc.

Are you adding 2x white labs plus more DAP?
If so, that's way too much.

[Stags]

First off, I can smell the hate coming, so feel free to flame away,

Stubbornly Lazy Yeast, I don't like the sound of that.
I'll have you know, trillions of yeast are my friend and I've never known one to be stubbornly lazy.


Both have more than adequate nutes- they’ve gotten double the recommended amount of white labs yeast nutes plus dead yeast, epsom salts, DAP, etc.

Are you adding 2x white labs plus more DAP?
If so, that's way too much.

You’re right I did go a bit overboard. I wasn’t worried about it, remembered reading somewhere that anything unused would sit in the trub unused until the yeasties came looking for it. Was I incorrect?

Fwiw, the ferment was already slow and I added that as a part of the process of elimination steps to try and troubleshoot.

[Stags]

Update for all-

I made the executive decision to run the last generation of UJ after it had been stuck at 1.016 for 3 days. So far the stripping runs have tasted normal save for a slightly gamey/ venison like aftertaste that I’m not sure I’m mad about. I’m pleased to report gen 9 has taken off like a rocket. I don’t know what may be the root cause or not because I incorporated many suggestions from this thread and a few of my own.

1. Aerated the piss out of it. Let it sit with an aerator for an hour immediately after mixing everything together
2. Reduced backset to 12.5% (5 gallons in 40 gallons)
3. Gave it a real good stir and broke up the trub bed as much as I could. Added boiling water to bring fermenter temp to 135° to kill the prior yeast bed. Repitched with WLP050 Tennessee whiskey yeast. (Would have left the old bed for science but I’ve been waiting for 6 mos to get my hands on these yeasties and didn’t want to wait to let em stretch their legs).

The airlock is breathing deep like a marathon runner. My only concern is she may run too hot- pitched new yeast at 100° and 95° and the fermenter is still at 94.2° 8 hours later.

[Bitter_Brew]

Having just had a devil of a stuck rum ferment (adjusted pH, more nutrients, more yeast, diluted multiple times... bastard is stuck at 1.06 from an inital SG of about 1.075 and still isn't moving) and doing a deep-dive on it, from what I can work out rum dunder is full of potassium chloride. As you get more generations in, it gets more and more concentrated. If you add too much, it'll slow your fermentation massively regardless of adjusting pH, nutrients etc.

So yeah, don't overdo it with late generation dunder/backset. I'm still trying to work out what the commercials do to avoid this issue.

[Stags]

Having just had a devil of a stuck rum ferment (adjusted pH, more nutrients, more yeast, diluted multiple times... bastard is stuck at 1.06 from an inital SG of about 1.075 and still isn't moving) and doing a deep-dive on it, from what I can work out rum dunder is full of potassium chloride. As you get more generations in, it gets more and more concentrated. If you add too much, it'll slow your fermentation massively regardless of adjusting pH, nutrients etc.

So yeah, don't overdo it with late generation dunder/backset. I'm still trying to work out what the commercials do to avoid this issue.

All I’d say is sg means nothing for rum… tough with all the unfermentables

[shadylane]

You’re right I did go a bit overboard. I wasn’t worried about it, remembered reading somewhere that anything unused would sit in the trub unused until the yeasties came looking for it. Was I incorrect?

That's incorrect.
The trub on the bottom is an inhospitable place for yeast.
Think of it as the graveyard of the fermenter.
Ya want the yeast active enough to keep everything stirred up until the yeast has finished it's job.

[Saltbush Bill]

Having just had a devil of a stuck rum ferment (adjusted pH, more nutrients, more yeast, diluted multiple times... bastard is stuck at 1.06 from an inital SG of about 1.075

I'm still trying to work out what the commercials do to avoid this issue.

Seems to me that your problems are because you havnt followed a reliable tried and true recipe......there is more than one listed in the forums recipe section.
Rum is one of the easiest things to ferment if you follow some simple rules.

[Ridgeback816]

When yeast work slower then I want them to I just say that the yeast are union workers

[Steve Broady]

When yeast work slower then I want them to I just say that the yeast are union workers

I’ve been a union member for 25 years, so I have to say that it’s not my job to argue with you on that one. And anyway, it’s time for me to take my break.

[Archee72]

When yeast work slower then I want them to I just say that the yeast are union workers

For me I say they must be non union workers brains

[Bitter_Brew]

Having just had a devil of a stuck rum ferment (adjusted pH, more nutrients, more yeast, diluted multiple times... bastard is stuck at 1.06 from an inital SG of about 1.075

I'm still trying to work out what the commercials do to avoid this issue.

Seems to me that your problems are because you havnt followed a reliable tried and true recipe......there is more than one listed in the forums recipe section.
Rum is one of the easiest things to ferment if you follow some simple rules.

I've been obsessively making rum for about the last 4 months to T&T recipes; but as happens to most people at some point, I got greedy.

In my case the greed was not trying to ferment to too high an ABV, but trying to use too much dunder, too many times. Could have been the molasses batch as well.

Unfortunately, especially with something like osmotic pressure, it's hard to know where the boundaries are until you find them. Total fermentable sugars and pH are much easier to work out. I suspect the commercials would measure salt concentrations, TDS etc and work out it, if they haven't just worked it out from 400 years of rum manufacturing.

Anyway, my consumption is so far below my production that I'm willing to risk a few failures to chase the exact product I want.

All I’d say is sg means nothing for rum… tough with all the unfermentables

If SG isn't moving, it isn't fermenting. I find it hard to tell by taste if a wash is done, especially with molasses washes.