Author Topic: Old Slurry - Building Back Up.  (Read 1293 times)

Offline blatz

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Old Slurry - Building Back Up.
« on: April 23, 2013, 07:39:34 AM »
haven't done this in forever as lately i've just been recycling yeast before it gets too old, but this time I need to restart an old slurry.

Have some 007 that was harvested on Jan 19th. 

Am brewing a black IPA on Sunday ~1.080SG - 12gal. 

Mrmalty says i need about 650bn cells.

i was thinking of: 4 heaping tablespoons in 1 liter flask (on stirplate), let that run through, then decant and pitch into 2L of new wort?

anyway I could keep the january slurry to use again in this manner, or is the risk of contamination too great now that I opened and extracted some? 

Or should I just bag it and use US-05? Was really trying to make something Sublimely Self Righteous like so was hoping to stick with 007, but...
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Offline Joe Sr.

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Re: Old Slurry - Building Back Up.
« Reply #1 on: April 23, 2013, 08:23:16 AM »
I have done what you are proposing, in essence keeping a "master slurry" that I build up for subsequent beers.

I have not yet had any issues with contamination and I've used slurry at 6 months or older and pulled portions of it at least two times.

Obviously, sanitation is important.

If your starter seems skanky, dump it and go with US-05.  Always good to have the dry yeast back-up.

I've only dumped one starter in the past couple of years, and I was probably over cautious on that one.
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Offline reverseapachemaster

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Re: Old Slurry - Building Back Up.
« Reply #2 on: April 23, 2013, 10:07:24 AM »
The contamination risk depends on your sanitation practices. If you're concerned about keeping a quantity of yeast that you can go back to, you may want to buy some smaller 1-2 dram vials and split up the slurry in multiple vessels. The smaller vials are usually safe to freeze with the yeast in a glycerine mix if you want to/can do that.
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Offline kylekohlmorgen

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Re: Old Slurry - Building Back Up.
« Reply #3 on: April 23, 2013, 11:00:34 AM »
At this point, the viability of that slurry is so low that you'll have hardly any cells left that are still alive and will be able to survive another series of growth phases.

If you're going to do multiple steps (esp. with a stir plate), just buy one packet of fresh yeast and step up from there.

www.yeastcalc.com does calcs for multiple steps.
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Offline mainebrewer

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Re: Old Slurry - Building Back Up.
« Reply #4 on: April 24, 2013, 04:42:29 AM »
I've done thisseveral times with old yeast, not four months old, maybe two months old.
I use about a 1/4 cup in 2L of wort and a stir plate.
Never had any issues, that I could taste.
I've always dumped the unused portion of the yeast.
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Offline narvin

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Re: Old Slurry - Building Back Up.
« Reply #5 on: April 24, 2013, 06:09:55 AM »
I wouldn't worry about contamination.  Do your beers go bad after 3 months?  ;)

You're going to have fewer viable cells but I don't believe Mr. Malty's doom and gloom estimate.  I just built up a starter from some 4 month old slurrry and it was active as any starter I've ever made.  I estimated 10%  viability and made a 2 step starter, and the cell count showed significantly more yeast than the Mr. Malty prediction, almost double.
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Offline kylekohlmorgen

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Re: Old Slurry - Building Back Up.
« Reply #6 on: April 24, 2013, 10:06:39 AM »
I wouldn't worry about contamination.  Do your beers go bad after 3 months?  ;)

You're going to have fewer viable cells but I don't believe Mr. Malty's doom and gloom estimate.  I just built up a starter from some 4 month old slurrry and it was active as any starter I've ever made.  I estimated 10%  viability and made a 2 step starter, and the cell count showed significantly more yeast than the Mr. Malty prediction, almost double.

Guess its like building up bottle dregs...

He mentioned he wanted to brew this weekend, so I didn't think he had time to revive and build up enough yeast for a 1.080 beer.
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Re: Old Slurry - Building Back Up.
« Reply #7 on: April 24, 2013, 10:48:10 AM »
I think this is doable but you're definitely pushing the clock. You might have to pitch Monday or Tuesday.

Viability should be in the 30-60% range, so let's say ~25 billion viable cells per 15 mL tablespoon. I'd put 1 tbsp in a relatively small amount of wort, say 250 mL, let it ferment out (hopefully within 24 hours), then smell and taste as a quick contamination check. If it seems OK step it up to 1 L, then 4-5 L.

You could start with a larger amount of slurry and do a smaller starter (or fewer steps), but this approach has the advantage of keeping the overall viability above 90-95%. A 2 L starter wouldn't get you anywhere near 650 billion cells anyway.

Once it's all said and done, what I usually do is pitch the yeast, then rinse out the vessel with some sterile tap water and store what's left for future propagations.
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Offline davidgzach

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Re: Old Slurry - Building Back Up.
« Reply #8 on: April 29, 2013, 07:38:53 AM »
Paul,

What did you end up doing?  I may be in this situation soon....

Dave
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Offline blatz

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Re: Old Slurry - Building Back Up.
« Reply #9 on: April 29, 2013, 07:48:32 AM »
Paul,

What did you end up doing?  I may be in this situation soon....

Dave

wow.  speak of the devil.  was just looking up this thread to post what I did.

couldn't quite do what sean recommended, though I think that is the way to go.

but...on the morning of the 24th, i made a 1L starter with 2-3TBL of slurry.  let that stir for all of Wednesday and by Thursday night it was clearly done. Crashed it, which thankfully didn't take long - small starter and being that it was 007 - tasted the wort - it was very, very fruity and had some strong esters but what to expect with english ale at 74-76df, right? 

Then on Friday I made a 4.5L starter, pitched into that and let it go Friday through Saturday afternoon, at which time the krausen started falling and the swirling appeared clumpy, so i figured it might not be ideal, but I crashed it at that point.  Brewed the black IPA on Sunday.  at about 9pm last night, there was a HUGE layer on the bottom of the flask, although it was still partially cloudy, but i poured off the spent beer, aerated and pitched at 60df. 

as of this morning, full krausen and thumping away. 
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Offline davidgzach

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Re: Old Slurry - Building Back Up.
« Reply #10 on: April 29, 2013, 12:03:54 PM »
Sweet.  I'll do the same with some 2007 from a lager earlier this year.......

Dave
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Offline blatz

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Re: Old Slurry - Building Back Up.
« Reply #11 on: April 30, 2013, 05:54:25 AM »
Update #2: the krausen was huge on the black ipa last night - almost had a blowoff (i never do - 2 gal of headspace and i pitch cool) and it smelled nice, hoppy and slightly fruity.  hopefully things are going well.
The happiest people don’t necessarily have the best of everything; they just make the best of everything they have.

BJCP National: F0281