Author Topic: What's your cutoff for viability in repitching a slurry?  (Read 621 times)

Offline Steve L

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What's your cutoff for viability in repitching a slurry?
« on: May 01, 2014, 06:23:40 PM »
I'm sitting on a 90ml slurry of WLP001 that is about 5 weeks old. Mrmalty has my viability at about 36-40%. I'm curious as to others opinions for their cutoff on for viablility in repitching yeast.
Specifically, I'm brewing a 2.5 gallon batch of a 1.068 IPA that needs about 117 billion cells. At the viability that MRMALTY has me at I'm looking at needing 154ml of slurry. I could do a 2 liter starter I suppose.

Looking for opinions from the repitchers ;D

Thanks,
Stevo
« Last Edit: May 01, 2014, 06:47:04 PM by swlusk »
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Offline beersk

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Re: What's your cutoff for viability in repitching a slurry?
« Reply #1 on: May 01, 2014, 06:31:25 PM »
I'd do a 1 qt starter for that. Should give you plenty. I usually will wait a month before I start making starters with slurry since I usually split the yeast cake up between 2 or 3 jars.
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Offline a10t2

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Re: What's your cutoff for viability in repitching a slurry?
« Reply #2 on: May 01, 2014, 11:39:22 PM »
MrMalty is really conservative with its viability formula. Assuming the yeast has been refrigerated the entire time, it's probably more like 60-70%. So 90 mL of packed slurry would be around 150-200 billion viable cells.
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Offline ynotbrusum

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Re: What's your cutoff for viability in repitching a slurry?
« Reply #3 on: May 02, 2014, 01:41:15 AM »
I assume half the slurry for lagers and 1/3rd of the slurry for ales after 30 days from original pitch .  Just based on experience - nothing scientific.
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