Author Topic: Reusing Yeast from Primary in new batch.  (Read 707 times)

Offline Mkpub

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Reusing Yeast from Primary in new batch.
« on: March 07, 2014, 03:36:31 AM »
I brewed an APA with WLP001 two weeks ago.  I just racked it to a Secondary carboy and saved 800ml of yeast slurry from the Primary carboy.  I want to brew an Am IPA Saturday and reuse this yeast in it.  Is the 800ml slurry too much, too little?  Any other suggestions?  Thanks, MK

Offline ynotbrusum

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Re: Reusing Yeast from Primary in new batch.
« Reply #1 on: March 07, 2014, 04:21:31 AM »
Depends on the batch size and gravity of the beer to be made by it.  I usually pitch about half a slurry from a lager and a third of a slurry for ales, if the same volume and same ABV.  If a slightly bigger beer, then half a slurry from a smaller beer...800 ml is a lot of slurry for an ale...I would go with maybe 500 ml of good, clean slurry for what you are proposing.  If you have a fair amount of beer in your slurry, then that might increase the amount you need to use.  I pour off the beer at the point I pitch the slurry.  The slurry starts to lose viability at a rate of 50% per month or so (possibly greater for some strains).  This is all anecdotal, so YMMV on these aspects, but generally what I use to estimate things.
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Offline erockrph

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Re: Reusing Yeast from Primary in new batch.
« Reply #2 on: March 07, 2014, 05:29:37 AM »
I'd recommend that you use a pitch rate calculator like mrmalty.com. That should eliminate the guesswork and give you an ideal recommendation for the beer you're brewing.
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Offline morticaixavier

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Re: Reusing Yeast from Primary in new batch.
« Reply #3 on: March 07, 2014, 06:38:23 AM »
I'd recommend that you use a pitch rate calculator like mrmalty.com. That should eliminate the guesswork and give you an ideal recommendation for the beer you're brewing.

+1. it's hard to say without seeing the slurry as well. How stiff/loose is it? how much non yeasty junk is in it. 800 ml is too much almost certainly but I don't know how much too much.
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Offline klickitat jim

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Re: Reusing Yeast from Primary in new batch.
« Reply #4 on: March 07, 2014, 07:25:44 AM »
It will be three weeks old, so I would restart by putting about 75-100ml in a 2000ml stired starter. Three weeks isn't a huge long time, but I'd restart it just to be sure. My procedure is to direct repitch if it's been a week or less, restart if longer

Offline morticaixavier

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Re: Reusing Yeast from Primary in new batch.
« Reply #5 on: March 07, 2014, 04:00:30 PM »
It will be three weeks old, so I would restart by putting about 75-100ml in a 2000ml stired starter. Three weeks isn't a huge long time, but I'd restart it just to be sure. My procedure is to direct repitch if it's been a week or less, restart if longer

well, it'll be three weeks from pitching but only a week from harvest. given that all my beers stay in primary more than a week it would always be a restart according to that procedure. You will probably get a younger population with a starter and assuming you gave them nutrients and enough o2 they will be raring to go but the harvested slurry is going to be just fine without a starter.

according to mr malty, 5.25 gallons of 1.065 ale wort with yeast harvested four days before brew day at the thinnest and most junky setting you want ~300ml. At moderate thickness and moderate junkiness you need only 100ml
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Offline klickitat jim

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Re: Reusing Yeast from Primary in new batch.
« Reply #6 on: March 07, 2014, 10:36:20 PM »
Misread the OP. I thought he racked to secondary two weeks ago... I restart if I have harvested the yeast more than a week before