Cold Fermentation method keeps failing me (stalling)

[Nick_D]

[Nick_D]

Here is my yeast for my next brew. On the left, freshly propagated with DME, yeast nutrient and constant aeration from a small amount of slurry collected from the last brew. On the right, harvested slurry from last brew under beer.
So, assuming 1.2 x 10⁹ cells/ml, that puts me in the ball park for pitch rate on a 12 -ish plato beer ? Does this look/sound about right ?

[Weizenberg]

[Weizenberg]

[Nick_D]

[Weizenberg]

0.5-0.7l per hl is a figure from Ludwig Narziss' book, Abriss der Bierbrauerei.

This is a very inaccurate figure though because it strongly depends on how one defines this. A while back Abbey recommended this tool, and I'm a happy user since

http://www.brewersfriend.com/yeast-pitc ... alculator/

Maybe you want to give it a go.

TBH with lagers fermented cold, I'd rather over-pitch a little, than under-pitch. Thus said, if not getting the cell count right is something that really bothers you, then you can always get a microscope and count them yourself

I'm happy with ranges and slowly fine-tuning things to suit me over time.

[Nick_D]

[Weizenberg]

When you infuse with hot water, you get a very fast rise and probably scorch some enzymes as well.

You are also lacking a gradual rise through the temperature range from 62 to 72C during which the enzymes are still active.

A difference in 10 minutes makes quite a difference in the beta range. I would mash at 62C for 40 minutes instead.

It's no good mashing longer than necessary either. So I'd work my way up.

Then there could be issues with how the yeast is handled.

Your thermometer is calibrated yearly, right?

[Nick_D]

[Weizenberg]

Oh, they are ready and beautiful!

This time I used WLP820 -- which made them a bit sweeter than with WLP838.

However, the yeast hasn't fully settled yet. So I'll probably filter one keg or will Umdruecken. I still need to get a good grasp on filtering (it's very hard actually), so it'll probably be that

Bear in mind that there are many other reasons than just mash which would cause the yeast to not attenuate fully.