Author Topic: Lifespan of harvested yeast.  (Read 1984 times)

Offline bluesman

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Lifespan of harvested yeast.
« on: March 05, 2010, 12:35:50 PM »
According to John Palmer one can harvest yeast from the primary and store it in a sanitized jar in the refrigerator for up to a couple of months. The yeast will turn brown as it ages. Once it turns the color of peanut butter it must be discarded because eventually the yeast will autolyze and die as its nutritional reserves are used up.

What are your thoughts on this?        Has anyone witnessed this effect?

I have witnessed this effect of browning after a couple of months. I have also had good results with six month old harvested yeast. I made a Marzen with a six month old yeast.

I made a starter from the six month old harvested yeast in accordance with Mr Malty using 25% viability. The starter was fermented and cold crashed then the spent wort was decanted and the slurry pitched into a 1.052 Octoberfest at 48F. The beer finished at 1.015 and was excellent. Clean and malty with a nice hop bitterness and flavor.

Survey says?
« Last Edit: March 05, 2010, 02:00:50 PM by bluesman »
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Offline blatz

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Re: Lifespan of harvested yeast.
« Reply #1 on: March 05, 2010, 12:52:26 PM »
I don't know - I'm just tagging this thread to see what the schmart folks say.

I've had harvested yeast for at least six months, but whiles its gotten darker, I would never describe it as peanut butter.  I don't wash my yeast, maybe that has an impact..
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Offline denny

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Re: Lifespan of harvested yeast.
« Reply #2 on: March 05, 2010, 01:11:39 PM »
I don't know - I'm just tagging this thread to see what the schmart folks say.

I've had harvested yeast for at least six months, but whiles its gotten darker, I would never describe it as peanut butter.  I don't wash my yeast, maybe that has an impact..

Exactly the same here...
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Offline a10t2

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Re: Lifespan of harvested yeast.
« Reply #3 on: March 05, 2010, 01:37:00 PM »
I recently grew up from a 17-month old slurry of 2206. The starters and the main batch behaved like I would expect. I think if you're conservative about your viability estimates (and have good sanitation, obviously) you can keep yeast in the fridge indefinitely. The viable cell count will get very low after a while, but I don't know of any reason that would affect the performance of the yeast that do survive.

Maybe Palmer meant that six months was the maximum for direct pitching? If so I wouldn't even go that long.
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Offline bluesman

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Re: Lifespan of harvested yeast.
« Reply #4 on: March 05, 2010, 01:45:08 PM »
I recently grew up from a 17-month old slurry of 2206. The starters and the main batch behaved like I would expect. I think if you're conservative about your viability estimates (and have good sanitation, obviously) you can keep yeast in the fridge indefinitely. The viable cell count will get very low after a while, but I don't know of any reason that would affect the performance of the yeast that do survive.

Maybe Palmer meant that six months was the maximum for direct pitching? If so I wouldn't even go that long.

Here's what Palmer says...

"If you harvest yeast from the primary fermentor, you will need to separate the yeast from all the trub that is mixed in. Professional brewers most often do this by "acid washing" the yeast--using acid to lower the pH to about 2.5 so that bacteria is inhibited and using whirlpool methods to seperate the heavier trub from the lighter yeast. But acid washing tends to inhibit the yeast too, and is not strictly necessary. You can simply use chilled boiled* water and two sanitized jars to separate the healthy yeast (white) away from the majority of the trub.

After racking the beer, swirl up the yeast layer on the bottom and pour some into a large sanitized jar (such as a mayonnaise jar).
Gently pour in some cold, boiled water and swirl it up to get all the yeast and trub in suspension.
Let the jar sit for a minute or three to allow most of the trub to settle to the bottom. Gently pour the cloudy water, containing suspended yeast, into another sanitized jar. Discard the dark trub.
Add some more water and repeat this procedure until you are left with a substantially light-colored yeast suspension and only a thin brown layer of dead yeast and trub on the bottom of the jar.
Store the jar in the refridgerator for up to a couple months. The yeast will turn brown as it ages. Discard it once it turns the color of peanut butter. Eventually the yeast will autolyze and die as its nutritional reserves are used up.
Pitch the yeast to a starter before using to ensure its vitality. If the starter smells wrong--rancid, vinegary, etc., the yeast may be contaminated. The dominant smell of a starter should be a yeasty smell, but sulfur smells are not necessarily bad, especially with lager yeast strains."

http://www.howtobrew.com/section1/chapter6-8.html



17 month old yeast...wow....I'm pleasantly surprised. That's good to know.

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Offline a10t2

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Re: Lifespan of harvested yeast.
« Reply #5 on: March 05, 2010, 01:55:20 PM »
Whoops, "couple months" and "six months" got mixed up in my brain by the time I'd finished reading the thread.
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Offline The Professor

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Re: Lifespan of harvested yeast.
« Reply #6 on: March 05, 2010, 02:12:23 PM »
I don't know - I'm just tagging this thread to see what the schmart folks say.

I've had harvested yeast for at least six months, but whiles its gotten darker, I would never describe it as peanut butter.  I don't wash my yeast, maybe that has an impact..

Exactly the same here...

And here, sort of... but my experience is with slurries just a bit shy of 6 months. 

I've rarely ever waited that long to brew, even in busiest of times, but then again I'm not one for switching yeast strains all that much either... I've never had more than two  (or three at most)  different strains of slurry in the fridge.  I don't wash the yeast, and longest I've ever kept one and reused it  was probably at about 4 months old.  I fed it up a bit two days before brewing and it worked fine and fast..and the finished beer was clean and good.  I think I've had good results because I am particular about sanitation, and I store the slurry very cold.
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Offline bluesman

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Re: Lifespan of harvested yeast.
« Reply #7 on: March 05, 2010, 02:19:11 PM »
I think I've had good results because I am particular about sanitation, and I store the slurry very cold.

Same here.
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Offline tygo

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Re: Lifespan of harvested yeast.
« Reply #8 on: March 05, 2010, 06:39:39 PM »
The last batch I did I poured about a gallon of cooled boiled water into the primary after I racked the beer and swirled it around.  Then I filled up a pint jar and put that right in the fridge.  The rest of it I poured into a big plastic pretzel container and let it settle overnight.  The I decanted the liquid into a 1 gallon jug and put it in the fridge, decanted again after 24 hours and poured the slurry into a small jar.

So what I've got is an ugly looking slurry jar and a small jar with a thin layer of very clean looking yeast at the bottom of it.
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Offline dean

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Re: Lifespan of harvested yeast.
« Reply #9 on: March 08, 2010, 05:56:29 AM »
I just saved some slurry from a batch that I left in the carboy for 5 weeks.  After siphoning the beer off I swirled and poured the slurry into two pint jars and 3 smaller vials which were half full of steril water.  After sitting in the fridge for half a day I looked at them, they all have 1/3 water on top, 1/3 yeast which is darker looking like peanut butter and 1/3 creamy white yeast at the bottom.  I'm not sure how I could separate it any further without losing the good yeast at the bottom?

Offline bluesman

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Re: Lifespan of harvested yeast.
« Reply #10 on: March 08, 2010, 07:45:17 AM »
I've never washed harvested yeast. I do the same as you Dean. I generally use about 2-3 Tbl of the harvested yeast to make a starter. I don't know what effect washing the yeast will have on the beer. Might have to try someday.
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Offline hankus

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Re: Lifespan of harvested yeast.
« Reply #11 on: March 09, 2010, 12:58:05 PM »
CONCLUSION from this thread (and similar)-U do NOT  (nor does anyone else) know how long YOUR yeast can be stored or the next one U save will live just as U do NOT know how fast U can drive on Dead man's curve on a rainy night-YMMV!!-save it until u need it and make a starter.

Offline dean

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Re: Lifespan of harvested yeast.
« Reply #12 on: March 10, 2010, 09:40:33 AM »
CONCLUSION from this thread (and similar)-U do NOT  (nor does anyone else) know how long YOUR yeast can be stored or the next one U save will live just as U do NOT know how fast U can drive on Dead man's curve on a rainy night-YMMV!!-save it until u need it and make a starter.

I think you can say that with a lot of the accepted norms, especially when brewing beer.   Look how opinion has changed with nearly every aspect of brewing already.  Everybody has an opinion and you know the rest of that saying... ;)  ;D

Offline dimik

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Re: Lifespan of harvested yeast.
« Reply #13 on: March 10, 2010, 02:46:05 PM »
I too keep yeast in sanitized jars for months and months without washing. Haven't had a problem making a starter with 6 month old slurry. Even pitched a jar of one month slurry without a starter and it made a great beer.
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Offline redbeerman

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Re: Lifespan of harvested yeast.
« Reply #14 on: March 10, 2010, 07:12:00 PM »
I too keep yeast in sanitized jars for months and months without washing. Haven't had a problem making a starter with 6 month old slurry. Even pitched a jar of one month slurry without a starter and it made a great beer.

Yep, my experience as well.
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