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General Category => Yeast and Fermentation => Topic started by: dzlater on February 18, 2013, 12:40:45 AM

Title: Can I vacuum seal yeast?
Post by: dzlater on February 18, 2013, 12:40:45 AM
Just another one of my wacky ideas.
Can I vacuum seal yeast?
Title: Re: Can I vacuum seal yeast?
Post by: Jimmy K on February 18, 2013, 02:32:51 AM
Do you mean a yeast slurry?
Title: Re: Can I vacuum seal yeast?
Post by: dzlater on February 18, 2013, 11:20:54 AM
Do you mean a yeast slurry?

Yea, the yeast I pour off from the bottom of the fermentor, to use on the next batch.
Title: Re: Can I vacuum seal yeast?
Post by: Jimmy K on February 18, 2013, 01:30:24 PM
Well I'm sure you can, but the real question is will it benefit the yeast during storage? I don't know the answer to that. Actually, I don't know what the benefit would be - so - What benefit do you think you'll get?
Title: Re: Can I vacuum seal yeast?
Post by: denny on February 18, 2013, 04:50:18 PM
Do you mean a yeast slurry?

Yea, the yeast I pour off from the bottom of the fermentor, to use on the next batch.

I don't know about your equipment, but my vacuum sealer doesn't do well with liquids.
Title: Re: Can I vacuum seal yeast?
Post by: Alewyfe on February 18, 2013, 05:12:08 PM
I don't think that would be of any benefit. Your yeast slurry, stored properly in the fridge is under a blanket of beer or distilled water, so it's not exposed to any air.

I just recently pulled a sample of yeast in a jar from my fridge. It was decanted and topped with distilled water. It was not a slurry, it had been pulled off a starter. It got forgotten about and it was dated February 2012. I was going to toss it out, but out of curiosity I stained some and checked the viability. It was 99%.
I triple checked it. It was 99%.

I'm sure these kind of results are strain dependent. (this happened to be W1469), but I think I will be storing most of my commonly used strains this way from now on. 
Title: Re: Can I vacuum seal yeast?
Post by: The Professor on February 18, 2013, 07:01:59 PM
I think there might be a benefit if your intent is to freeze the slurry for any extended period.  The barrier bags that the vacuum seal units employ would definitely protect against freezer burn...but again, it's probably only of benefit if your intent is to freeze it for a few months or more.

You'd probably need to freeze the slurry first in a ziplock bag, then as soon as it has frozen remove it from the ziplock and seal the now frozen slurry the usual way in a vacuum seal bag.
Title: Re: Can I vacuum seal yeast?
Post by: Alewyfe on February 18, 2013, 08:00:02 PM
I think there might be a benefit if your intent is to freeze the slurry for any extended period.  The barrier bags that the vacuum seal units employ would definitely protect against freezer burn...but again, it's probably only of benefit if your intent is to freeze it for a few months or more.

You'd probably need to freeze the slurry first in a ziplock bag, then as soon as it has frozen remove it from the ziplock and seal the now frozen slurry the usual way in a vacuum seal bag.


Sorry, but this is not good advice. You need to add a glycerin solution to yeast before freezing. The purpose of the glycerin is to keep the yeast from getting freezer burn (freezing solid and drying out) So you will not have a solid that can be transfered to another bag. The glycerin will maintain the yeast in a viscous liquid state.
Title: Re: Can I vacuum seal yeast?
Post by: The Professor on February 18, 2013, 09:24:31 PM
...
Sorry, but this is not good advice. You need to add a glycerin solution to yeast before freezing. The purpose of the glycerin is to keep the yeast from getting freezer burn (freezing solid and drying out) So you will not have a solid that can be transfered to another bag. The glycerin will maintain the yeast in a viscous liquid state.


That's one way of looking at it, I guess. 
Really, I only offered my suggestion up because it worked perfectly fine for me the one time I did it 25 years ago (I had to go  out of town on a location shoot for a couple of months).  I never had to do the freeze thing again since shortly after that, I learned to preserve my house yeast on slants.

Bottom line is that the freezing/vacuum bag worked perfectly fine, and the yeasties  in fact produced a  very robust fermentation (even without the glycerin treatment). 
I'll concede that others' mileage may vary, but It produced no negative issues for me  (maybe I got lucky??).
Title: Re: Can I vacuum seal yeast?
Post by: tschmidlin on February 19, 2013, 05:50:57 AM
Many cells will survive freezing, many will not.  Good thing there are a ton in a slurry. :)

It is not best practice to allow yeast to freeze without adding some cryoprotectant, glycerol being a common and easy to find one.  Although with today's frost free freezers, the repeated freeze thaw cycles will eventually kill off all of the cells whether cryoprotected or not.  Even using a cooler to minimize temperature swings the viability goes down after a few years.

If you are going to put your yeast in the freezer I recommend adding enough glycerol that it won't freeze solid at 0F, that way you avoid the constant freeze/thaw cycles completely, the solution is just always liquid.  That's ~50% glycerol.  You wouldn't store huge slurries this way, just samples to grow up what you need.
Title: Re: Can I vacuum seal yeast?
Post by: dzlater on February 19, 2013, 10:28:30 AM
Thanks for the info.
My daughter gave me her FoodSaver because she didn't use it, so I have been on a vacuum sealing kick lately.
I just figured if it helps to preserve a pound of chicken, it might help preserve a half liter of yeast.
Title: Re: Can I vacuum seal yeast?
Post by: Kit B on February 21, 2013, 12:15:01 PM
I'm curious about how the cells would handle the negative pressure.
Title: Re: Can I vacuum seal yeast?
Post by: anje on February 21, 2013, 08:28:03 PM
I'm curious about how the cells would handle the negative pressure.
In a bag, I don't think it matters. A jar might be interesting.
Title: Re: Can I vacuum seal yeast?
Post by: Horseflesh on August 14, 2017, 06:19:52 AM
Sorry to bring this thread back from the dead, but it's the only one I've seen discussing this topic!

I intend to try the normal yeast washing protocol, but I do want to store the harvested yeast in vacuum bags. The reason is simply convenience--the bags will take up less space than jars. They are also dirt cheap so I don't have to worry about cleaning them for re-use.

My sealer does handle liquids fine, and I can control the amount of vacuum that the yeast are subject to during the process. I can also adjust the re-pressurization speed to give them a gentle ride. The seal bar clamp mechanism is vacuum-powered though, and so you need to evacuate at least ~60% of the atmosphere to get a good seal. This takes about 10 seconds.

In the years since this thread was last active has anyone had good or bad experiences with this idea? My main concern is killing the yeast with vacuum exposure. I don't have a microscope yet and so I can't inspect the yeast for vacuum damage. Can anyone suggest how I might check the viability other than making a starter?