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General Category => Yeast and Fermentation => Topic started by: cenosillica on August 31, 2011, 11:36:14 PM

Title: 3 month old Slurry - too old?
Post by: cenosillica on August 31, 2011, 11:36:14 PM
I brewed in April and dumped the yeast slurry in May when kegging to a sterilized mason jar that went immediately to my refrigerator. I'm planning on brewing the same recipe with an OG of 1.070. It is a British Ale Yeast (Dogfish Indian Brown Ale clone - all-grain from BYO clone recipes).

I typically do a 1L yeast starter several days in advance.

Having never tried to re-use yeast, is it too old for me to try to re-pitch this slurry into a starter?



Title: Re: 3 month old Slurry - too old?
Post by: tygo on August 31, 2011, 11:55:33 PM
Yes, three months is too old to pitch directly.  It probably still has some viable yeast in it though.  If it still smells good you could make a starter several days in advance and smell/taste the starter wort.  If that seems okay then you're probably fine.

Personally though I wouldn't use it.  Just my opinion.
Title: Re: 3 month old Slurry - too old?
Post by: cenosillica on September 01, 2011, 12:08:00 AM
ugggh, so what is the best way to sustain a strain if you don't plan on using that yeast for several months?
Title: Re: 3 month old Slurry - too old?
Post by: rbclay on September 01, 2011, 12:32:46 AM
no- not too old to put in a starter and use, in my opinion. i personally think it may not even be too old to pitch directly. what is the approximate volume of slurry?

Quote
Yes, three months is too old to pitch directly.
maybe, but that wasn't the OP question. they want to put it in a starter.

sounds like you have yourself a good opportunity to to a yeast experiment. split the wort. pitch half with the slurry in a starter. pitch the other half with a fresh pack/ vial done in a starter.
Title: Re: 3 month old Slurry - too old?
Post by: tygo on September 01, 2011, 02:56:12 AM
Like I said, he could try to make a starter and see how it comes out.  You'd probably want to start smaller and step it up.  The viability of the yeast in the slurry is going to be pretty low after three months. 
Title: Re: 3 month old Slurry - too old?
Post by: cenosillica on September 01, 2011, 02:48:08 PM
The approx volume of the slurry is about a pint and a half with the yeast settling the top layer somewhere between 1/16 and 1/8th of an inch.

In the future, if I wanted to reuse the yeast but had no plans on brewing immediately after racking and or kegging... what do you do? I have bought and read Chris & Jamil's book on yeast but there is a grey area they don't explain... The beer is done, the yeast cake is on the bottom of your fermenter. I want to retain this yeast and use it anytime within the next 6-12 months. So what is the best practice here?
Title: Re: 3 month old Slurry - too old?
Post by: Joe Sr. on September 01, 2011, 02:58:50 PM
I don't know if it's best practice, but...

I typically bottle a portion of each batch.

I've had good luck pitching the dregs into a starter and re-using yeast in that fashion.
Title: Re: 3 month old Slurry - too old?
Post by: bluesman on September 01, 2011, 02:59:09 PM
To mitigate any potential off flavors, and have clean healthy vibrant yeast, I recommend rinsing the yeast slurry to remove trub and hop material from the slurry prior to use, then grown up a yeast starter from a 1 liter size and step accordingly to the targeted (appropriate) size starter. I use mrmalty.com to estimate the required size starter.
Title: Re: 3 month old Slurry - too old?
Post by: cenosillica on September 01, 2011, 03:12:16 PM
Bluesman - that I would have no problem doing but what if I wanted to hang on to it for a while? Your suggestion assumes that I'm going to pitch into a new batch fairly quickly.

I'm curious as to how I can reliably get the yeast from the primary to long term storage.
Title: Re: 3 month old Slurry - too old?
Post by: bo on September 01, 2011, 03:16:21 PM
I've used a large slug of 5-6 month old slurry without any problems at all.
Title: Re: 3 month old Slurry - too old?
Post by: bluesman on September 01, 2011, 03:44:54 PM
Bluesman - that I would have no problem doing but what if I wanted to hang on to it for a while? Your suggestion assumes that I'm going to pitch into a new batch fairly quickly.

I'm curious as to how I can reliably get the yeast from the primary to long term storage.

After primary fermentation is complete, rack the beer from the slurry. Then swirl the entire slury to get all of the yeast into suspension and transfer into a clean and sanitized container.

Boil some water and chill.

Pour some water into the container with the yeast and shake to make homogenous, then allow to settle for 10-15 min. After settling, pour the yeast into another sanitized container leaving behind the trub and hop material.

Repeat this "yeast rinsing" process 2-3 times until you see the yeast brighten slightly.

This process helps clean the yeast by removing trub and hop material while also helping mitigate potential bacterial spoilage. It also helps make a cleaner beer.
Title: Re: 3 month old Slurry - too old?
Post by: bluesman on September 01, 2011, 03:53:11 PM
I would also like to mention that I still recommend making a starter after long term storage of a yeast slurry, eventhough it has been rinsed.
Title: Re: 3 month old Slurry - too old?
Post by: morticaixavier on September 01, 2011, 04:22:36 PM
for long term storage of yeast isn't there a process that allows freezing? I know you still need to make a starte but...
Title: Re: 3 month old Slurry - too old?
Post by: dbeechum on September 01, 2011, 04:27:29 PM
From Mike's own site: freezing with glycerin

http://www.ipass.net/mpdixon/Homebrew/Freezing%20Yeast.htm
Title: Re: 3 month old Slurry - too old?
Post by: morticaixavier on September 01, 2011, 04:28:09 PM
Thanks Drew, I figured someone would chime in with details
Title: Re: 3 month old Slurry - too old?
Post by: bo on September 01, 2011, 04:47:02 PM
What's the longest amount of time anyone here has gone with freezing and had acceptable results?
Title: Re: 3 month old Slurry - too old?
Post by: tschmidlin on September 01, 2011, 04:53:49 PM
You can freeze your yeast solid, but I think you are better off using enough glycerol to get it to freezer temps without freezing.  That way the cells are as cold as you can get them, but it avoids a lot of the problems that freezing causes.  For home, I think it is a good way to go.  But even in the fridge it can last a long time.  Rinse it a couple of times with distilled water and store it with distilled water and it should last you 6 months easily.
Title: Re: 3 month old Slurry - too old?
Post by: bluesman on September 01, 2011, 05:04:04 PM
Rinse it a couple of times with distilled water and store it with distilled water and it should last you 6 months easily.

+1
Title: Re: 3 month old Slurry - too old?
Post by: tschmidlin on September 01, 2011, 05:05:34 PM
What's the longest amount of time anyone here has gone with freezing and had acceptable results?
I've gone years with excellent results.  But mine are at -80C.
Title: Re: 3 month old Slurry - too old?
Post by: bo on September 01, 2011, 05:21:56 PM
What's the longest amount of time anyone here has gone with freezing and had acceptable results?
I've gone years with excellent results.  But mine are at -80C.

Crap. My freezer only goes down to -70.
Title: Re: 3 month old Slurry - too old?
Post by: tschmidlin on September 01, 2011, 05:23:32 PM
What's the longest amount of time anyone here has gone with freezing and had acceptable results?
I've gone years with excellent results.  But mine are at -80C.

Crap. My fridge only goes down to -70.
If you can really get them that cold then they will be fine for many years in a 20% glycerol solution.
Title: Re: 3 month old Slurry - too old?
Post by: cenosillica on September 01, 2011, 07:07:59 PM
I think he was being sarcastic... -70 to -80 the yeast will be shivering so still that they won't notice the 10 degree difference.   :)


Great stuff! I'm going to try this glycerol mix.