Guide to Making a Frozen Yeast Bank

It depends on the yeast strain, but count on 6 months for sure. Many could last for o two or three years.

The only one I have had fail before one year was a hefe yeast (Wyeast 3068). Apparently, they are notoriously difficult to keep viable.

But a lot of it depends on your storage conditions, too. Make SURE you store your yeast inside a cooler with ice packs inside your freezer because your freezer temps will fluctuate, which is probably the hardest thing on the yeast.

Best of luck if you try it!

hmm... just got ahold of a flask and stirbar and made a stirplate. I ordered 24 of those 16ml vials, a couple droppers, and a few smaller pyrex beakers for working with the yeast. I have fresh WLP400 belgian and WLP775 english cider yeast vials I'm going to bank up probably next week. I'm also going to take a sample of my Pistoles I just kegged and generate a WLP575 Belgian Golden starter out of some beer. Ill pack away 6 vials of each which will leave me 6 empties for some other yeast. Maybe I'll grab a WLP001 sample from someone in our homebrew club and start using that instead of Nottinghams.

My coworkers are calling me the mad scientist now... flasks, stirbars, yeast cultures, glycerine...lol..

Just tried this over the weekend. I have four pint-size mason jars with 1086 in them and can't wait to try them out.

Thanks for the thread!

Back around post 66 we were discussing is layering was a problem. Mine are stored vertically and totally layered. They are also frozen solid.

I just pitched a 5 month old Wyeast 1332 with no problems. I warmed in room temp water for 2 hours and pitched into a 500ml wort.

That's good to hear -- thanks.

I've learned a bit more about this, and I don't think layering is such a big deal anymore. If the yeast are 'acclimatized' in the fridge for 48 hours before freezing, and the glycerine solution is kept well mixed during that time, then they will become should become plenty cold-hardy.

One question I have, when you make the glycerine solution, are you adding water and glycerine, or just glycerine and a little bit of beer from the starter?

biggenius29 said:

One question I have, when you make the glycerine solution, are you adding water and glycerine, or just glycerine and a little bit of beer from the starter?

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I try NOT to add beer if possible. I crash cool my starters so that all the yeast drops to the bottom of my flask, and then I pipette off the bottom in the thickest part of the yeast 'sludge'. If some beer makes it in there, so be it. But now I shoot for about 15-20% glycerine, 30-35% water (both sterilized in the pressure cooker), and about 50% yeast slurry.

I've been pitching the whole starter and then harvesting from the carbuoy post fermentation. After harvesting, the yeast is washed and I mix 20% glycerin with 80% wash slurry. In effect, I'm mixing 20% glycerin with about 65/15 distilled water & yeast.

Thanks! This really helps to simplify the process for me! Now to convince my wife to let me take MORE freezer space.....


~M~

When you put the vials in the pressure cooker, I see you leave the caps on the vials. When everything cools will they implode on themselves or are they able to withstand the vacume?

I put the caps on but I don't screw them on tight. Leave them loose so that they can pressurize and de-pressurize without exploding.

biggenius29 said:

When you put the vials in the pressure cooker, I see you leave the caps on the vials. When everything cools will they implode on themselves or are they able to withstand the vacume?

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FWIW, If you screwed them tight, they would pressurize on temp rise, and return to normal upon cooling (no vacuum created). If you had special mason jar type lids, they would seal upon cooling and thus create a vacuum inside the vessel.

First off - awesome write up.

Is there any other way to store the yeast in the freezer? I have a big freezer that's quite full and doesn't have a defrost cycle, not much room to fit a (small) cooler inside, any alternatives?

You would probably be okay if there is no defrost cycle. The only time you will see temperature fluctuations is when you open the door. Sounds like you have alot of mass in there so it shouldnt affect you too much.

I spoke with my friend who studied yeast for her master's work and asked about freezing/thawing of vials in order to avoid having to reculture.

She says that you just need to take out the vial, scratch a bit of the surface with an inoculating loop to pick up a few cells and plate that on a petri dish. The next day after letting that grow a sample can be inoculated into a liquid nutrient medium. The important part is to not let the main vial thaw.

I imagine it would be alright to not go to a petri dish and just go straight to a liquid culture as the main reason to use the dish is to make sure you are only culturing a single cell. If you are really nit picky it might be important but in general I'd imagine its fine.

I have yet to try any of this but thought I would pass along the information.

Yes, I am sure this would work, but it would be a lot more effort. If you are going to these lengths anyways, you are probably better off just maintaining slants in the fridge.

The idea behind the frozen yeast bank is that you keep multiple vials of yeast stored until they are ready to be used. Thaw one as you need it, and pitch the whole vial to get a starter up and running. Once you run out of vials, just make up another batch. The intent is to be simple and easy.

scottfro said:

I imagine it would be alright to not go to a petri dish and just go straight to a liquid culture as the main reason to use the dish is to make sure you are only culturing a single cell. If you are really nit picky it might be important but in general I'd imagine its fine.

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This is the same thing as just thawing one of many vials, but you start with more cells. I pick some cells with a loop and innoculate liquid media in my lab, but I have much more access to shakers, warm rooms, incubators and such than most people. With beer yeast, picking a single colony is not always a good idea, as I found out with a Wit I made with yeast cultured from a bottle, there are sometimes several different yeast strains in a single 'culture' for brewing...that was a weird beer, but quite good...

well it seems to me that having a "mother culture" thats always frozen in the freezer that you keep picking off of would be a whole lot easier than having to make 10 vials of that culture so you can pitch a whole vial in at once. Then you can be sure you always have a nearly pure strain frozen whenever you need it.

Virtuous said:

You would probably be okay if there is no defrost cycle. The only time you will see temperature fluctuations is when you open the door. Sounds like you have alot of mass in there so it shouldnt affect you too much.

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Thanks.

I've read on the MaltoseFalcons yeast write up that storing the tubes in alcohol can provide insulation and a super-cooling effect, might fill a small tupperware container with meths and drop the tubes in there and stick the thing right at the back of the freezer.

scottfro said:

well it seems to me that having a "mother culture" thats always frozen in the freezer that you keep picking off of would be a whole lot easier than having to make 10 vials of that culture so you can pitch a whole vial in at once. Then you can be sure you always have a nearly pure strain frozen whenever you need it.

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Except you don't want to thaw then refreeze the yeast, you're viability will drop when you do that.

Professor Frink said:

Except you don't want to thaw then refreeze the yeast, you're viability will drop when you do that.

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right, i'm continuing talk about my post a few posts back about scrapping off a few cells from the FROZEN culture. and then replacing the frozen culture to the freezer before any thawing occurs.

Fantastic article, thanks very much

sorry, im a little new at this

but what is the point of doing this?

all I see is you freezing yeast, why are you not just buying it when you need it?

BryanZ said:

sorry, im a little new at this

but what is the point of doing this?

all I see is you freezing yeast, why are you not just buying it when you need it?

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Why not just go buy a beer at the store while you're at it... its just another aspect of homebrewing, and with freezing or washing being so easy why pay $8 for a vial of yeast (you can also grow your own hops if you like to). As with many aspects of brewing, you can keep it very simple and do very little or you can get very complicated and do a whole lot, just another part of the hobby.

BryanZ said:

sorry, im a little new at this but what is the point of doing this?

all I see is you freezing yeast, why are you not just buying it when you need it?

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The idea is to buy one package of yeast, build a starter from it for your next brew --- but before you do, steal 6 - 10 small samples of yeast slurry that you can freeze. Then, when it comes time to brew again with that yeast, you will have some on hand to build up a starter from. MUCH cheaper than buying a new package each time. Plus, if you use a bunch of different yeasts, you can bank them all away and have a great selection of yeast in your freezer -- no need to be driving down to the LHBS each time you need new yeast.

I went to the grocery store last night and the only glycerin that I could find was premade suppositories.

They're 5.5mL in size, so it's the perfect pre-measured size, but a little expensive because of the packaging. Anyone know if Walgreens or CVS carries bottles?

Thanks to everybody for all the good information. I was inspired to hit up my local science supplies shop -- Colorado Scientific. These guys have all kinds of toys for brewers -- vials, glassware, stir plates, agar, etc etc. I was sorely tempted to pick up some premade agar petri dishes, but was content to grab a handful of 6 ml vials.

Hopefully, I'll be able to get some culture media going tonight, and be ready to inoculate a couple of slants with some of the WLP400 I'm going to brew with this weekend. Y'all have inspired me.

One question, though. I'm confused as to whether slants can be safely frozen without glycerin. Can I just wrap my slants in a couple of icepacks after a few days of growth, and move them from RT to fridge to freezer, or will this be a problem for vitality? I seem to hear differing opinions.

I only brew about once a month, but I'd like to be able to start banking some yeast. So, do I need to top off slants with glycerin before freezing, or RDWFYY (RDW, Freeze Your Yeast).

Chris_K said:

Here's a dozen of the vials in 16ml for $6

Cynmar

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That place has a $25 minimum. Any other source on vials?

slimer said:

I went to the grocery store last night and the only glycerin that I could find was premade suppositories.

They're 5.5mL in size, so it's the perfect pre-measured size, but a little expensive because of the packaging. Anyone know if Walgreens or CVS carries bottles?

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Walmart here carries a 6 oz. bottle in health and beauty.
It's near the cortizone and espom salts type stuff.

FlyGuy said:

BryanZ said:

sorry, im a little new at this

but what is the point of doing this?

all I see is you freezing yeast, why are you not just buying it when you need it?

Click to expand...

The idea is to buy one package of yeast, build a starter from it for your next brew --- but before you do, steal 6 - 10 small samples of yeast slurry that you can freeze. Then, when it comes time to brew again with that yeast, you will have some on hand to build up a starter from. MUCH cheaper than buying a new package each time. Plus, if you use a bunch of different yeasts, you can bank them all away and have a great selection of yeast in your freezer -- no need to be driving down to the LHBS each time you need new yeast.

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Also don't forget about the limited edition yeasts from Wyeast's VSS(now called Private Collection) program. Try walking into your LHBS today and getting Pacman(Sept-Dec 06'), Flying Dog(Jan-Mar 07') or Fat Tire(Oct-Dec 07') yeast. Yeah, Wyeast might bring them back to the public again in the future, maybe. BTW anyone tried Wyeast 2450PC "Denny’s Favorite 50" yet?

I've been holding off opening my Fat Tire yeast until I accumulate the materials necessary to freeze some samples... I just ordered vials and picked up a flask. Just need something along the lines of a pipit.

so when you guys are all talking about slants- what type of agar are you using? also im wondering how you stage those since the yeast cells will still proliferate on the slants even in the fridge...

found this one...do you think this would work? or am i better off using the glycerin freeze method?

http://www.sigmaaldrich.com/img/assets/6840/70196_Wort_Agar.pdf

Most of us aren't using slants because of the volume of yeast produced in a wort, and the extra work involved in propagation. I use glycerin and store 32ml samples ready to pitch into a starter. They look like this:

pldoolittle said:

Most of us aren't using slants because of the volume of yeast produced in a wort, and the extra work involved in propagation. I use glycerin and store 32ml samples ready to pitch into a starter. They look like this:

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what ratio of glycerin/water/yeast do you use? and have you had any viability issues? IM seriously looking into this because yeast is becoming the most expensive part of my brewing now that i planted hops. I wonder if anyone grows and malts their own grain?

also where did you get the 32ml tubes from?

scinerd3000 said:

what ratio of glycerin/water/yeast do you use? and have you had any viability issues? IM seriously looking into this because yeast is becoming the most expensive part of my brewing now that i planted hops. I wonder if anyone grows and malts their own grain?

also where did you get the 32ml tubes from?

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Take a sample of suspended yeast (in wort/beer/etc) and mix it so that the final concentration is 15-20% gylcerol (glycerine).

scinerd3000 said:

found this one...do you think this would work? or am i better off using the glycerin freeze method?

http://www.sigmaaldrich.com/img/assets/6840/70196_Wort_Agar.pdf

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That would work for slants. Sigma-aldrich - that could go on an NIH grant...

scinerd3000 said:

what ratio of glycerin/water/yeast do you use? and have you had any viability issues? IM seriously looking into this because yeast is becoming the most expensive part of my brewing now that i planted hops. I wonder if anyone grows and malts their own grain?

also where did you get the 32ml tubes from?

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I've grown up at least a half dozen frozen tubes, and never had viability issues. Some have taken a little while to get going, but they all worked fine.

scinerd3000 said:

what ratio of glycerin/water/yeast do you use? and have you had any viability issues? also where did you get the 32ml tubes from?

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20% glycerin to slurry (~6-7ml/tube). No issues. I found the tubes on ebay for about 50c each..

So I picked up a bottle of glycerine from the Rx today. It says for external use only though. In this diluted form that you end up making is it ok to use? Or do I need to get some type of food grade glycerine?

wedge421 said:

So I picked up a bottle of glycerine from the Rx today. It says for external use only though. In this diluted form that you end up making is it ok to use? Or do I need to get some type of food grade glycerine?

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As long as it's just glycerin and not glycerin with {rose hips, aloe, XXXX}, it's fine.