Frozen yeast bank procedure

[Tony B]

Thanks Tony B and Bassman2003, very understandable instructions. I have 3 liquid strains on order to start my yeast bank. One difference I see in your methods is making a starter first or just using the fresh yeast from the container. I was thinking of doing the latter. Making perhaps 5 tubes of each. I bought 15 ml tubes. Also seems like the amount of glycerin is different. Is there a range, percentage that should be used?

TBA, making the tubes straight from the original pouch is a fine idea. I make a starter first because I generally add new strains to my yeast bank as I’m preparing to brew a batch, so in order to have a proper pitch and bank some yeast, I build a starter first.
As for the glycerin, if I remember correctly, the info I read advised to use a 25% glycerin solution by weight. Not sure exactly how accurate that is, but it’s worked for me. The idea with that and using isopropyl alcohol in the freezing process is to prevent ice crystals from forming and destroying the yeast cell walls.
Best of luck in your yeast bank!

 

[TBA]

I will see what the dates are on the pouches and if they are not super fresh I will make at least a small starter before banking.

 

[Broothru]

This is so great, thanks! I'm just about to embark on this.

Does anyone keep any sort of tracking spreadsheet or anything?

I’ve kept a running spreadsheet of all my frozen samples (approx. 30 separate yeasts). Some are multiple samples. They’re stored in 50ml centrifuge vials inside a soft-sided Thermos lunch box. There are frozen gel packs inside and outside the Thermos box to prevent thawing during defrost cycles of the freezer.

With two Thermos boxes of frozen yeast vials plus a metric crap ton of saved hops, there’s no empty space in the freezer section of the beer fridge. But my biggest problem is actually using the yeasts that I’ve frozen. I have a really bad habit of always wanting to use yeast strains I haven’t tried before. So my ‘bank balance’ keeps growing, but I never make any ‘withdrawals.’

 

[Bassman2003]

Thanks Tony B and Bassman2003, very understandable instructions. I have 3 liquid strains on order to start my yeast bank. One difference I see in your methods is making a starter first or just using the fresh yeast from the container. I was thinking of doing the latter. Making perhaps 5 tubes of each. I bought 15 ml tubes. Also seems like the amount of glycerin is different. Is there a range, percentage that should be used?

I use 25% Glycerin + 25% wort + 50% Yeast slurry. That is what I settled on in researching the topic.

 

[Tony B]

I use 25% Glycerin + 25% wort + 50% Yeast slurry. That is what I settled on in researching the topic.

Why wort vs water?

 

[Bassman2003]

From my understanding, wort/beer is the best medium to store yeast for this purpose. Water does not have anything for the yeast. Wort has pretty much everything they need. What you are asking the yeast to do is take a long nap and hope they do not die along the way

 

[Broothru]

From my understanding, wort/beer is the best medium to store yeast for this purpose. Water does not have anything for the yeast. Wort has pretty much everything they need. What you are asking the yeast to do is take a long nap and hope they do not die along the way

I’ve always used glycerin (30 ml) mixed with sterile water (70 ml) to make a 30% glycerin solution. I add equal amounts of thick yeast slurry and 30% glycerin/water solution to a 50 ml centrifuge tube for freezing.

The mixture results in a 15% glycerin mix which coats the yeast cells to prevent cell damage due to freeze/thaw cycles. The glycerin is food safe and doesn’t require decanting after thawing, so the whole tube gets chucked into the Erlenmeyer flask with starter wort when it’s time for propagating.

 

[kurds_2408]

I’ve started doing this with 50ml tubes but haven’t used one yet. Most mine are save yeast cake. But I have a question. I do 20ish ml each of yeast and my glycerin solution with some room for expansion. When using a yeast calculator for my starter do I enter 20ml or 40ml for my starting slurry? I’m assuming 20ml but wanted to check.

 

[Broothru]

I’ve started doing this with 50ml tubes but haven’t used one yet. Most mine are save yeast cake. But I have a question. I do 20ish ml each of yeast and my glycerin solution with some room for expansion. When using a yeast calculator for my starter do I enter 20ml or 40ml for my starting slurry? I’m assuming 20ml but wanted to check.

My assumption would be 20 ml as well. The glycerin and water are simply solutes for the slurry and don’t provide anything that would otherwise be a growth media for yeast.

 

[Bassman2003]

I’ve always used glycerin (30 ml) mixed with sterile water (70 ml) to make a 30% glycerin solution. I add equal amounts of thick yeast slurry and 30% glycerin/water solution to a 50 ml centrifuge tube for freezing.

The mixture results in a 15% glycerin mix which coats the yeast cells to prevent cell damage due to freeze/thaw cycles. The glycerin is food safe and doesn’t require decanting after thawing, so the whole tube gets chucked into the Erlenmeyer flask with starter wort when it’s time for propagating.

Just going by the "Yeast" book by Chris White and others' experiences.

 

[Broothru]

Just going by the "Yeast" book by Chris White and others' experiences.

It hard to find fault or argue with a PhD Microbiologist!

The goal is to have sufficient glycerin to prevent bursting of yeast cells during the freeze/thaw process. Both sterile water and the liquid in wort dilute the glycerin to a concentration optimal to give this protection: 15% for sterile water, 25% for wort, though the other components in wort would lower the exact composition to something closer to 15%. Fifteen percent concentration of glycerin appears to give better cell protection than higher (or lower) concentrations.

In the final analysis it would seem that both processes give similar levels of protection. One difference I can see that favors using a sterile glycerin/water media verses wort is the
sterility. Wort by its very nature is a growth media for not only yeast but other spoilage colonies as well that would compete with thawing yeast cells. Infection risks would be less likely in a (mostly) sterile environment when attempting to propagate a starter from a thawed sample, even though the risk is probably quite low for either process.

 

[Bassman2003]

It is tough track the impact upon re-entry with regards to impact at our level. I think wort is favored for the journey as it gives some sustenance over the long nap. The whole trick to freezing yeast is getting them to the other side in good shape. Cells still die along the way, just at a slower pace. Reviving tired, undernurished cells just leads to poor outcomes in the end. They say in the book that freezing at consumer temps is an in-between process. Not cold enough to truly preserve the cells. So they actually do not recommend it but it can work to some extent.

I am trying what I call 'extended brinking' or 'long term repitching' now. Which is harvesting yeast from your fermenter aseptically, storing in CO2 at cold fridge temps and then using like a repitch. This is less stressful on the cells than freezing and due to the lack of oxygen, the cells are kind of in a state of stasis. I am hoping to get 2-4 months between pitches and still have plenty of healthy cells in the 2 liter bottle with the Kegland "Tee" on the top. I will make a video about it if I see success. My goal is to be able to keep a slurry for 4 months and direct pitch it in a batch with a great fermentation outcome.

 

[dhoyt]

Ive found that it definitely takes 48hrs to fully propogate enough yeast from the small amount in a vial. I make a 1L ( 101g DME) starter for Kveik yeast, a 1.5L starter for standard ale yeasts and haven't yet tried a lager yeast, but would plan on either a 2L ( 202g DME) starter or 2 step starter for that.

I tried double checking brewfathers yeast starter calculator and the only options are for packages of yeast. I guess my question is, would there be any reason why these numbers would change, like the age of the vile? If so how did you get your numbers? Did you use a calculator and which one?

 

[IslandLizard]

I tried double checking brewfathers yeast starter calculator and the only options are for packages of yeast. I guess my question is, would there be any reason why these numbers would change, like the age of the vile? If so how did you get your numbers? Did you use a calculator and which one?

Many of us use this yeast starter calculator (it's free):
https://www.brewunited.com/yeast_calculator.php

 

[Tony B]

Yeast starters. Make sure you have a plan B , but otherwise, … relax, have a home brew.
This is about 24 hours after pitching a previously frozen vial of 6ml yeast slurry combined with 6ml cryo-preservative. WLP-521 Hornindal. This yeast is HUNGRY !

 

[Tony B]

Last week I made about a 1,700ml starter from one if my frozen vials of WLP-521 Hornidal. I’ve been liking this yeast a lot for my no ferm temp control ales.
Anyhow, I was planning to split the starter for two batches, but life got in the way and I was only able to brew one. So, lemons for lemonade, I poured about 1,000ml into my batch and stuck the remainder in the fridge for a few days with the plan to make some more vials for freezing.
I did so tonight. After decanting, I was able to make 12 vials with the remaining slurry. Will post here if I see any difference in gen 3.

 

[Tony B]

I have a few vials of WLP-521 from my original session but decided to see how the recent generation works out. I originally started from a lab packaged pouch and made about 10 vials. As stated above, I recently made 12 more vials. Since the first set of vials were made from a starter that originated from a retail package, lm saying those were gen 2. The new vials should then be gen 3 and a starter from those should be gen 4. Is that correct?
Anyhow, I made a starter Thursday night and it was blowing up by the time I got home from work on Friday and looks more than ready to pitch when I brew a batch tonight.

 

[Antti]

I'm really interested with storing and growing up self-sufficient yeast bank!

Is there anything that I could use instead of the DME?
Or could I make too big batches of wort for a brew and freeze the excess wort in small containers, melt it and grow the yeast in there? So instead of using DME?

Small background info, for perspective:

I'm quite new into this, but doing everything from scratch (malting, drying, kilning, toasting).

Next year we will be growing our own barley in this small old farm.

If I manage to grow yeast, then we'd have grown everything scratch. But DME is store-bought that's why I'm asking.

 

[khannon]

I'm really interested with storing and growing up self-sufficient yeast bank!

Is there anything that I could use instead of the DME?
Or could I make too big batches of wort for a brew and freeze the excess wort in small containers, melt it and grow the yeast in there? So instead of using DME?

Small background info, for perspective:

I'm quite new into this, but doing everything from scratch (malting, drying, kilning, toasting).

Next year we will be growing our own barley in this small old farm.

If I manage to grow yeast, then we'd have grown everything scratch. But DME is store-bought that's why I'm asking.

About once a year I brew a batch of "wort" with some added nutrients and no hops. I then pressure can in ball jars in a couple of sizes to make starting and stepping up yeast easy. That way I don't need freezer space.

If doing it this way, I suggest boiling the wort to get protein break before canning(which will boil it again). If you don't it all ends up in the jars.

You can also make it whatever OG you want, .020 for starting and .040 for once it is going is what I do, I make the whole batch at .040 and dilute in the smaller "jam" jars.

 

[Bassman2003]

Is there anything that I could use instead of the DME?
Or could I make too big batches of wort for a brew and freeze the excess wort in small containers, melt it and grow the yeast in there? So instead of using DME?

It is not food safe to boil, freeze and thaw wort. Its pH is above pH 4.6 which is the divider line for allowing dangerous substances like Botulism to grow. Pressure canning is the only safe way to store wort and works well. Best to add some yeast nutrients to it as well when you grow the yeast.

 

[Miraculix]

I have no idea how anything should grow in frozen wort. Just do not let it stand around for ages after thawing and you are good.

 

[Bassman2003]

Science is science and it happens if we believe it or not. It is important to state the facts when dealing with food safety on a homebrew forum where convenience usually wins out over solid practice. Since Antti stated they were new to the hobby, might as well learn things the right way from the start rather than start bad habits.

 

[Miraculix]

Science is science and it happens if we believe it or not. It is important to state the facts when dealing with food safety on a homebrew forum where convenience usually wins out over solid practice. Since Antti stated they were new to the hobby, might as well learn things the right way from the start rather than start bad habits.

Science is not a religion.

There is nothing growing in frozen wort.

 

[Tony B]

On another note, I pitched the starter above into a batch around 11:30pm on Saturday night. It was going nuts by next morning. I just got home from work and took a look. No more yeast activity. It still blows my mind how fast that stuff gets the work done.
I’ll let it ride a few more days before kegging.

 

[PCABrewing]

Olive oil. Optional.

Just curious, what is the Optional olive oil for?

 

[day_trippr]

From a BYO article:

"The idea behind olive oil aeration was to directly give the yeast the UFAs that they would normally synthesize from oxygen. This would eliminate the need to aerate the cold wort (which primes the beer to stale more quickly) or the yeast in storage (which causes them to burn up their glycogen and trehalose reserves)."

Cheers!

 

[Tony B]

That sounds a lot better than what I was going to say. Haha
When doing my own research, prior to starting my frozen yeast bank, I read or heard something about olive oil helping to reduce the yeast’s requirement for oxygen and that was good enough for me. I always have olive oil on hand and have seen no ill affects from using it. I want to make the yeast as happy as possible.

 

[day_trippr]

It takes a vanishingly small amount of EVO, too.
Like the coating on the tip of a toothpick. Remarkable...

Cheers!

 

[Miraculix]

It takes a vanishingly small amount of EVO, too.
Like the coating on the tip of a toothpick. Remarkable...

Cheers!

I don't remember where exactly I saw it, but I've seen people getting mixed results with this practice. I wouldn't count on this technique alone tbh.

One question which needs to be addressed and Which usually is omitted within the olive oil crowd, is ufa synthesis really the only thing that yeast does with the oxygen? My guess is that it's not the only thing.

 

[IslandLizard]

Or could I make too big batches of wort for a brew and freeze the excess wort in small containers, melt it and grow the yeast in there? So instead of using DME?

Sure, I do that all the time.*
I too doubt anything can grow in frozen wort. But I would definitely reboil the wort after it has been stored frozen, just for all security. Something could have gotten in during packaging, storage, defrosting, and handling.

That said, depending on how much extra wort you make and store, it could be more efficient, storage-wise, to freeze concentrated (high gravity) wort. Then dilute, reboil, and chill before use as starter wort.

You can also reclaim wort that's left behind in the kettle after filling the fermenter. You'll have to strain/filter it to separate it from the trub. I would reboil it to pasteurize, before freezing.

* On a somewhat larger scale, I brew 3-5 gallons (11-19 liter) of concentrated starter wort (1.090-1.115), hopped to about 50-60 IBU, stored in 48 oz (1.4 liter) stubby, plastic cottage cheese containers. They stack well.