Cold Fermentation method keeps failing me (stalling)

How are you fermenting?

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Ancient Abbey
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Ancient Abbey » Sun Oct 02, 2016 8:23 am

Are you performing your FFT with bread yeast or with a sample from your beer after you've pitched the lager yeast?

Are you using a finishing gravity hydrometer? Refractometer calculations can vary by a whole percent.

Take a sample of your beer that seems stuck, put it in a sterile jar of some kind and let it warm up to room temp (or warmer). If it finishes out, then time and temperature is your issue. If it doesn't, then explore other rabbit holes.
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Re: RE: Re: Cold Fermentation method keeps failing me (stalling)

Postby Natebriscoe » Sun Oct 02, 2016 8:30 am

Weizenberg wrote:I'm not sure I understand the question

Does it change anything by holding at 42f until final gravity is reached then continue ramping down?
(I personally haven't noticed anything off)
Last edited by Natebriscoe on Sun Oct 02, 2016 8:30 am, edited 1 time in total.
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Ancient Abbey » Sun Oct 02, 2016 8:31 am

Nick_D wrote:My determination is made of steel ;) I've dumped over 130 liters of undrinkable, failed cold ferment beer so far in my learning curve. No sense turning back now. Once I get that issue sorted, it will be a slippery slope to perfection. I welcome it.

I've never had a beer turn out undrinkable because it was a couple of points high at the end of fermentation. All of the mono- and disaccharides are long gone, and maltotriose is flavorless. You should only be experiencing a sensation of slightly more body in the beer. If it is undrinkable, then there may be other issues at play here.
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Nick_D » Sun Oct 02, 2016 9:37 am

Ancient Abbey wrote:Are you performing your FFT with bread yeast or with a sample from your beer after you've pitched the lager yeast?

Are you using a finishing gravity hydrometer? Refractometer calculations can vary by a whole percent.

Take a sample of your beer that seems stuck, put it in a sterile jar of some kind and let it warm up to room temp (or warmer). If it finishes out, then time and temperature is your issue. If it doesn't, then explore other rabbit holes.

FFT with the slurry leftover in the starter flask after pitching.

I use a Hydrometer. I only use the refractometer to measure wort before the boil, so I know if I'm in the ball park with boil off etc. Then after the boil in conjunction with the hydrometer for OG.
I will pull a sample from the current keg which is about 2.5 points of finishing and see what it does.
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Nick_D » Sun Oct 02, 2016 9:45 am

Ancient Abbey wrote:
Nick_D wrote:My determination is made of steel ;) I've dumped over 130 liters of undrinkable, failed cold ferment beer so far in my learning curve. No sense turning back now. Once I get that issue sorted, it will be a slippery slope to perfection. I welcome it.

I've never had a beer turn out undrinkable because it was a couple of points high at the end of fermentation. All of the mono- and disaccharides are long gone, and maltotriose is flavorless. You should only be experiencing a sensation of slightly more body in the beer. If it is undrinkable, then there may be other issues at play here.

Hmmm. My working assumption has been it is un-processed fermentation by products that the yeast haven't had the muscle to clean up (some combination of diacytl and acetaldehyde?). As an example, my first attempt at cold fermentation failed on every front, not enough yeast, dropped temp way too fast, lack of aeration etc. It had the same flavour and was similarly stuck, but I made a fresh starter, dropped it in, and let it sit at room temp for 3 weeks. It finished out, and the off putting, or rather, obscuring flavours dissapeared. It was a horrible beer, but it tasted like beer. So I don't think it's an infection. Possible just super poor yeast performance leaving undesirable by products ? I assumed this was a normal transitionary flavour before the yeast finished up. Wish I could give you a sample to taste!

My current batch is a vast improvement in that it has a much lower level of this flavour (whatever it is), and the only thing I did differently was give it several hours of pumped air for oxygenation, as opposed to the shake method.

Food for thought, what if one severely over pitches ? I imagine there are consequences there also. My current yeast batch I will be pitching consists of 180ml of dense collected slurry form the last batch, and about 100 ml dense freshly propagated. How's that sound?
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Ancient Abbey » Sun Oct 02, 2016 10:04 am

Yeah, if you are trying to nail the textbook cold ferment, then don't taste it for a month. It takes time and you'll be pre-maturely frustrated.

I don't do the ultra-cold ramp down for secondary fermentation anymore, as I get better flocculation, clearer beer and less yeast in the keg if I let it go to terminal as I am dropping from 9C to 6C. It doesn't get to cold-lager until after EVG. I'm finding yeast in the serving vessel is more damaging than not following the Narziss secondary fermentation profile.
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Weizenberg » Sun Oct 02, 2016 10:14 am

Narziss mentions that oxygen in excess of 30mg/l should be avoided.

For cold fermentation a DO meter should be high on the list (that's why I initially bought one).

There are factors that can influence fermentation tremendously. Here is an example.

OG: 12.5%
WLP: 838
Pitch: 5 Celsius
Main: 7 Celsius (day 3, for 4 days)
Transfer: 6C

The beer developed beautifully. Suddenly, it started to turn badly. It wasn't nice at all. Loads of things were suspected, autolysis amongst them. I kept the beer on schedule and was finished after 8 weeks. The end result was stunning!

What happened? That's a good one. I exclude autolysis because that is permanent damage. I did ramp down a bit too fast and the yeast really doesn't like it at lower temperatures. As one goes lower the temperatures need to drop even more carefully.

I think I had a bit of thermal stress or I was simply tasting by-products that weren't decomposed yet. I could have had a lot of unattractive tasting particles in suspension as well. Hard to tell w/o lab analysis.

So, don't dump. For all it's worth you simply didn't give the beer enough time to finish. It takes a bit of "Fingerspitzengefuehl" but thats the fun of it!

Hope this helps
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Nick_D » Sun Oct 02, 2016 10:17 am

Ancient Abbey wrote:Yeah, if you are trying to nail the textbook cold ferment, then don't taste it for a month. It takes time and you'll be pre-maturely frustrated.

I don't do the ultra-cold ramp down for secondary fermentation anymore, as I get better flocculation, clearer beer and less yeast in the keg if I let it go to terminal as I am dropping from 9C to 6C. It doesn't get to cold-lager until after EVG. I'm finding yeast in the serving vessel is more damaging than not following the Narziss secondary fermentation profile.

Actually, what I did this time round sounds quite similar to what you have described. Pitched at 5.5C, rose to 8.4C over 2 days, fermented there until 50% attenuation (1.5 days) then started lowering by 1C per day. It was attenuating so fast, I only got the beer down to 6.7 ish or so by the time it was 1.014 or thereabouts, and I transferred. Left it at that temp for a week without dropping any further. Spund gauge came up to full pressure (0.9 BAR), then I started lowering by 0.5 per day, intending on halting again at 4.5C until FG. Figured with the pressure it had built, it must have come close to FG, but I was very frustrated to find it had basically only come down 3/4 of a gravity point at most. I read other people on here reaching close to final gravity a week after moving over to spunding.
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Nick_D » Sun Oct 02, 2016 10:24 am

Weizenberg wrote:Narziss mentions that oxygen in excess of 30mg/l should be avoided.

For cold fermentation a DO meter should be high on the list (that's why I initially bought one).

There are factors that can influence fermentation tremendously. Here is an example.

OG: 12.5%
WLP: 838
Pitch: 5 Celsius
Main: 7 Celsius (day 3, for 4 days)
Transfer: 6C

The beer developed beautifully. Suddenly, it started to turn badly. It wasn't nice at all. Loads of things were suspected, autolysis amongst them. I kept the beer on schedule and was finished after 8 weeks. The end result was stunning!

What happened? That's a good one. I exclude autolysis because that is permanent damage. I did ramp down a bit too fast and the yeast really doesn't like it at lower temperatures. As one goes lower the temperatures need to drop even more carefully.

I think I had a bit of thermal stress or I was simply tasting by-products that weren't decomposed yet. I could have had a lot of unattractive tasting particles in suspension as well. Hard to tell w/o lab analysis.

So, don't dump. For all it's worth you simply didn't give the beer enough time to finish. It takes a bit of "Fingerspitzengefuehl" but thats the fun of it!

Hope this helps


That is indeed helpful. Then my 12hour aeration venture could in fact be quite harmful even. Perhaps I will give half that this time, or less.

I won't dump it, don't worry. Worst case scenario is I'll learn something out of it by letting it go a few months.

It is now sitting at 4.5 C. What would you recommend temperature wise? let warm a little ? or let it go at 4.5 C ? The sample I pulled had loads of suspended yeast, so at least the yeast hasn't flocced and just totally gone to bed. Good point about the suspended material. Beer won't taste much like beer if it looks like a milk shake I suppose!
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Weizenberg » Sun Oct 02, 2016 10:28 am

I cannot tell what schedule to use. Eventually one ends up at -1C in classic cold.

It may go a little faster and clear up quicker if you set the lower limit to +1.5C - I'd drop the temperature veeeery slowly. Like 0.2C per day max.

You need to find what works for you and your setup.
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