Cold Fermentation method keeps failing me (stalling)

[Natebriscoe]

[Natebriscoe]

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]

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.

[Natebriscoe]

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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[Weizenberg]

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?

[Nick_D]

[Weizenberg]

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.

[Natebriscoe]

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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[Weizenberg]

I'm not sure I understand the question

[Nick_D]