Re-using Yeast

[BobtheBrewer]

I harvested yeast (half a Pet bottle) from a Coopers Pale Ale put down with two kit yeast sachets. Dropped it into my next Pale Ale and watched the krausen go through the airlock on day one. Has settled down now, but I think that after three days the fermentation will be finished. Maybe half next time?

Bob

 

[buttersd70]

Bob,
check Jamils calculator....link

 

[flattop]

Calculator looks good but how do you decide on your yeast concentration and non yeast percentage?

 

[Bribie G]

BribieG,

Is that new avatar a photo you took from home last week?

Bob

:icon_offtopic: No it's from the Courier Mail

Back to the Possum shortly when things settle down. On the subject of photography the possum was a shot that I took of a beast that mugged me at Bargara (Kelly's Beach) when it went for some bananas I had on the patio table at a resort. Never resist a possum, they move faster than a Gen Y on crack and they have sharp teeth like you wouldn't believe :lol:

 

[buttersd70]

Calculator looks good but how do you decide on your yeast concentration and non yeast percentage?

sorry, should have linked to the main page here - forgot that there is no 'home' link from the calc itself.
there is an instruction guide here and that specific question is answered here

 

[rich_lamb]

The MrMalty calculator of Jamil's is about the best tool we have when using harvested yeast, but it clearly shows that estimating cell counts this way is just about impossible.
With all those variables - time/viability, compacting, and crud content it's real guesswork to get the cell count right.

My approach now is to use guesswork with very fresh yeast - pitched directly - and I'm still trying to get a handle on just how much to use based on the wort composition and flavour profile I'm going for.

But in the more common case where I have the yeast for a while I will use a starter from a smaller amount of slurry to both recondition the yeast and provide a more reliable cell count - since cell count is "somewhat" controlled/limited by the starter temperature and volume.
(at least that's what the Wyeast guy at ANHC claimed, when I asked him if older smack packs reduced the cell count in a starter)

 

[buttersd70]

The MrMalty calculator of Jamil's is about the best tool we have when using harvested yeast, but it clearly shows that estimating cell counts this way is just about impossible.
With all those variables - time/viability, compacting, and crud content it's real guesswork to get the cell count right.

Absolutely agree, it's still a lot of guesswork and judgement involved...like how thick is 'thick'. It's still a guess, but it's better than nowt. Agree that starters should be used with older yeast, if for no other reason than to confirm viability.