A few sanity checks

[Techbrau]

[mchrispen]

[lupulus]

Thoughts on lagering...
I have set my lagering freezers at 0.5C based on reading many years ago and have not questioned the temperature.
Why 3C? Yeast would certainly be more active, but I would have thought that clearing would take longer. Maybe it is the other way, and they clear faster because they run out of nutrients/ substrate faster at 3C.
What do you all think? I will be doing some reading in the following days.

[Techbrau]

I lager at 3C because I only have two temperature controlled chambers (one for fermentation, one for serving) and I prefer to serve at 3C instead of 0.5C. I did lager some batches colder (around 0C) about a year or so back, and I don't think I noticed much difference. If I had three chambers to play around with, it would be interesting to do some side-by-sides.

[lupulus]

Thanks

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[Owenbräu]

Bamforth did an interview a few years back, where he described the differences in flocculation, precipitation and settling rates with temperature. I don't recall it exactly, but the difference between lagering at 1C vs -1C was somewhere around 3:1. In other words, every day at -1C was roughly equal to 3 days at 1C.

[lupulus]

Happy New Year CT
I remember the interview. I thought at the time that it was with ale yeast as there was no true lagering period. I think this was when he was working at Bass (not a study). The way I recall the process being described is that there was a process to reduce VDK levels (I think it was a small temperature increase for a few days), followed by a 2-day crash at -1C to reduce yeast and particulate matter and then off to packaging. I do not recall whether they filtered. So, he could have been talking about an process to drop particulate matter including ale yeast.
My question was comparing lagering at 3C, which should increase metabolism of the yeast vs 0C which should have a faster particulate matter drop.
I may be wrong but I think it was the diacetyl podcast...

[Ski]

Apart from the lagering time difference, is there any upside or downside to say 3º instead of -1? I lager in a fridge rather than a freezer, and it needs a fan to get down to -1, and of course the compressor runs for longer.

[lupulus]

I have not been able to find much literature on lagering. I will keep looking. An interesting point (Künze) is that yeast does not metabolize diacetyl at 0C. If this were to be absolute (no reason to doubt it), it seems to me that lagering at 2-3C may be better for the conditioning that takes place during lagering, whereas 0C is probably better for the particle precipitation. So, an interesting protocol would be to lager at 2-3C for 2 weeks and finish off at 0C (which I am sure is not simple for homebrewers with 1-2-3 lagering fridges).
A large German brewery is likely to measure VDKs during lagering so they can adjust.
I will move this question to a separate thread as it seems to be an interesting question...