Cold Fermentation method keeps failing me (stalling)

[Nick_D]

Ok, got it. I'll do a starter as you've described. Unfortunately I can only shake at this point, as my stir plate died. How long should I let the starter go? Pitch at high krausen? or crash the yeast out and decant the liquid off?, leaving only the yeast slurry? I'm not sure I'd want to pitch 2 + liters of DME starter. I've always let them (starters) ferment out, and crash at 2C or so. Though I realise now that this probably leads back to the yeast being starved of oxygen, like a normal yeast cake...

Thanks!

EDIT:

I just saw the additional info you posted which answered my questions, please disregard my above questions obviously.

Ok cool. I feel more confident now. Thank you! I'll report back in a few days, with hopefully good news!

[Nick_D]

Now, this may be a dumb question.
Would there be any benefit in adding a little O2 towards the end of primary, before transfer to spunding? Say, with 1.5 - 2 Plato fermentables remaining. You know, give the yeast some extra horsepower to finish out strong? From what I've read in another thread (regarding oxygen scavenging of brewing water, with just a little yeast, and a little fermentable like dextrose), it seems the yeast would scavenge any incoming oxygen, so long as they still have things to chew away at.

Terrible idea? Worth trying? Any thoughts?

[Bryan R]

I have seen no reasons to want to do this. I have had over 100 cold fermentation and spund batches with zero issues. The racking into the spund keg rouses the yeast plenty enough.

[Brandon]

[Nick_D]

It was a silly question I know. I think with so many disappointments (over 100 liters down the drain) trying to get this right, I've gotten desperate and am losing my mind...

But with the advice and information that has been generously shared with me here in my short time on this forum, I believe I'm on the right track, and armed with the right tools (DO meter not included).

I suspect I might have been shocking the yeast whilst lowering my temps also, even though I proceed at 1C per day, in 0.5 increments every 12 hours. I have a thermowell in my fermentation vessel, and use an STC-1000 temp control (using an old fridge as a fermenting chamber). When lowering the temp, the fridge works hard to get it down the 0.5C, and then overshoots because the ambient is obviously well below the set temp. E.g. Setting 6C, the temp of the fermenting beer will reach 6C, then continue down to 5.7 (as the STC 1000 has a minimum temp differential of 0.3), then my lamp turns on to heat it back to 6C, where it then overshoots to 6.3C before cooling again. That's a lot of back and forth in temperature....

Perhaps I'd do better to take the temperature probe out of the thermowell when cooling the beer to Spunding transfer? I believe this would make for a less bumpy ride down in temp.

I'm just thinking out a loud here. Thanks again for your responses. - Nick

[Bryan R]

Well its one of 3 things... You are either not pitching enough yeast, oxygenating enough, or both. Solve that, you solve the fermentation issues.

For instance, I just fermented my festbier. I brewed and pitched yeast on Saturday 7/9 (1.056og). It then Fermented at 45f. It went into spund today at 1.016 at 40f. It will then sit there until fg is hit, then go into lagering chamber.

Its not easy, or fail proof. If it was everyone would be doing it(enter the accelerated).

[Brandon]

[Owenbräu]

I'm generally pitching 200-300ml of settled yeast cake. As often as possible, I will combine it with yeast fresh off the stir plate. There is a big difference in the number of cells and the vitality of the cells between an oxygenated starter and a yeast cake. I will turn the stir plate off at the end and let the yeast finish out and flocculate on their own. I don't crash cool it, as it puts them into a deeper dormancy and increases the lag times once pitched.

[Owenbräu]

[Bryan R]

All my chambers have fans. Way more efficient.