Cold Fermentation method keeps failing me (stalling)

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Natebriscoe
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Re: RE: Re: RE: Re: Cold Fermentation method keeps failing me (stalling)

Postby Natebriscoe » Sat Oct 01, 2016 3:04 pm

Nick_D wrote:
Natebriscoe wrote:
Nick_D wrote:Just took a hydrometer reading of my current batch (now holding at 4.5C until attenuation - if it ever gets there). It's dropped maybe half a point since transferring (6.5 days ago), and is now 1.0135 or so. Not terribly encouraging. How fast do other peoples secondary ferments reach final gravity ?
Brewing again tomorrow, but this time with some darned wyeast yeast nutrient. Pitching collected yeast slurry combined with an aerated starter I added yeast nutrient to.

I think I would hold above 5.5c until fg is reached.
In my experience lager yeast stall below 42f.

I'm certainly in no position to disagree, but that seems to be in contradiction to what other people here seem to be experiencing ? The paper regarding LODO Helles brewing suggests holding at 3C until FG, and someone here mentioned holding at 4.5C as a safer bet. I don't mean to come across as ungrateful for the feedback. It's all good, and I appreciate every bit of it. Just confused by conflicting information.
I have held a batch a primary temp (8C) after transferring on an earlier batch, and it stalled all the same, so I suspect temp isn't the issue. I'm hoping adding yeast nutrient at the end of the boil, will finally get me over the line, if all other things are in order.

I'm not saying everyone else is wrong either, just my experience. The brewers from devil's backbone had come to the same conclusion as well.
I'm sure yeast strains has something to do with it as well.
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Natebriscoe » Sat Oct 01, 2016 3:11 pm

Also is there a possibility that your temp control is out of calibration? 1 degree would make a big difference.

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Weizenberg
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Weizenberg » Sat Oct 01, 2016 6:24 pm

There are many potential issues.

As long as the yeast isn't going towards 0 there will always be activity. I had well propagated (under pure oxygen) and viable yeast happily fermenting at 1.5C even.

Getting viable yeast as well as the cell count right is paramount for cold of fermentation.

Kunze recommends at least 3mgl and Narziss advocates 8-9mgl of oxygen. Those unable to measure o2 in the wort are flying blind and will get to inconsistent results.

When was your reference thermometer calibrated last? I've seen guys with their thermometers out by 2-5C -- which can have disastrous consequences. Thermometers should be calibrated yearly.

Your malt quality can also have a substantial impact. If you suspect malt as the fault, then doughing in low at 35C for 15-20 minutes, then infusing with hot water up to your target temp of 72-65C (do not heat it up! You want to avoid any activity of porteolytic enzymes), could also help.
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Natebriscoe » Sat Oct 01, 2016 7:47 pm

I wouldn't argue that there was still activity at all, but every time mine goes below 42f it slows down to the point you can't see any signs.

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Re: Cold Fermentation method keeps failing me (stalling)

Postby Weizenberg » Sat Oct 01, 2016 11:40 pm

I pitch at 5C/41F and often ferment at 7C/45F

Are you sure your yeast is viable enough? How do you measure acitivity? How much oxygen did you have at pitch? Did your pH increase?
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Nick_D » Sun Oct 02, 2016 4:25 am

Weizenberg wrote:There are many potential issues.

As long as the yeast isn't going towards 0 there will always be activity. I had well propagated (under pure oxygen) and viable yeast happily fermenting at 1.5C even.

Getting viable yeast as well as the cell count right is paramount for cold of fermentation.

Kunze recommends at least 3mgl and Narziss advocates 8-9mgl of oxygen. Those unable to measure o2 in the wort are flying blind and will get to inconsistent results.

When was your reference thermometer calibrated last? I've seen guys with their thermometers out by 2-5C -- which can have disastrous consequences. Thermometers should be calibrated yearly.

Your malt quality can also have a substantial impact. If you suspect malt as the fault, then doughing in low at 35C for 15-20 minutes, then infusing with hot water up to your target temp of 72-65C (do not heat it up! You want to avoid any activity of porteolytic enzymes), could also help.


The plot thickens! Malt quality. I had not thought of that at all. I'm using Weyermann, however as I currently have no mill, I have it milled, then posted to me. The malt arrives some 3 days later, and sometimes I don't get to brew for another week..... I know this will have dire consequences in terms of freshness and oxidising the cracked malt, but could that deteriorate the nutritional value of the malt for the yeast performance ? And I haven't been using any yeast nutrient at all either...... (but have some now for my next attempt).

My thermometer was calibrated a few months ago in a biology lab, next to one of their lab spec thermometers, so that base is covered.

Ok, this time round I will dough in thick and low at 35C as you suggest for 20 mins, then proceed to the rest temp (I only have enough mash space to raise the temp once after 35C) and add 2.5 grams of yeast nutrient in the boil. Also I'm pitching fresh yeast I propagated with constant aeration, and yeast nutrient (which I haven't done before).

Something I noticed on my last batch, was my yeast cake left over after transferring seems a lot less than what people here are reporting. After settling, it was only 170 ml of dense slurry under the beer. Not even enough to re-pitch?? This might further indicate poor yeast growth/lack of nutrients ? That time round I'd pitched 300 ml of dense slurry.

Thanks again for being patient, and ever helpful.
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Weizenberg » Sun Oct 02, 2016 5:12 am

Indeed, there could be a combination of factors at play.

However, your low volume of yeast made points towards it being a growth problem (not enbough oxygen, nutrients, viability or count)

For a plethora of reasons, milling fresh will become inevitable at some stage. It depends on how far you want to take it and your determination. German breweries are superb masters of chemical engineering. The idea with the pot and the wooden paddle yields a result, but if you want something as well made as the German beers you like, then approaching their setup will become inevitable of sorts (there is some variation though).

Milling in itself is quite interesting since you can condition the malt and reduce LOX if the water is at 80C.

I'd consider a pH-, DO-, refracto- and calibrated thermometer alongside a malt mill and the ability to perform temperature controlled fermentation as the minimum equipment of any serious brewer ;)

Thus said, if you just pitched yeast from vials then it's a crap shoot. Yeast loses its viability over time, so without an appropriate propagation step (or steps) it's a crapshoot.

I often heard people here say that one should never brew before the yeast is ready. It's great advice and I certainly heed to it.

I'd try that first before investing in more equipment. After all, you can easily test this without investing into more equipments.

You can also try a mash pH 5.4 and a 40 min rest at 64C.
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Natebriscoe » Sun Oct 02, 2016 5:32 am

This is all fantastic info, and by all means keep it coming. Question: What does it hurt by holding at 42f vs 40-41 until tg?

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Re: Cold Fermentation method keeps failing me (stalling)

Postby Weizenberg » Sun Oct 02, 2016 5:46 am

I'm not sure I understand the question
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Re: Cold Fermentation method keeps failing me (stalling)

Postby Nick_D » Sun Oct 02, 2016 6:05 am

Weizenberg wrote:Indeed, there could be a combination of factors at play.

However, your low volume of yeast made points towards it being a growth problem (not enbough oxygen, nutrients, viability or count)

For a plethora of reasons, milling fresh will become inevitable at some stage. It depends on how far you want to take it and your determination. German breweries are superb masters of chemical engineering. The idea with the pot and the wooden paddle yields a result, but if you want something as well made as the German beers you like, then approaching their setup will become inevitable of sorts (there is some variation though).

Milling in itself is quite interesting since you can condition the malt and reduce LOX if the water is at 80C.

I'd consider a pH-, DO-, refracto- and calibrated thermometer alongside a malt mill and the ability to perform temperature controlled fermentation as the minimum equipment of any serious brewer ;)

Thus said, if you just pitched yeast from vials then it's a crap shoot. Yeast loses its viability over time, so without an appropriate propagation step (or steps) it's a crapshoot.

I often heard people here say that one should never brew before the yeast is ready. It's great advice and I certainly heed to it.

I'd try that first before investing in more equipment. After all, you can easily test this without investing into more equipments.

You can also try a mash pH 5.4 and a 40 min rest at 64C.


This time round I'll nail the nutrients, and take that out as a factor, whilst again giving a long time on the sterile air for oxygen. But maybe not quite 12 hours..... That was definitely a big step in the right direction in itself though, and was very visible in the ferment activity. Then I'll be left with yeast viability/count as the remaining factor.

Trust me, a decent mill is on my 'to do' list. Has been for a while now. I loathe being at the mercy of having others do it for me. I look forward to it. Current priority is DO > PH > Mill. Have the refraco, thermometer and temp control. At this stage, I will be satisfied succeeding at the cold ferment, even if the beer is compromised by oxidised malt.

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.

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