Frozen yeast bank procedure

[Miraculix]

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.

Hops stress yeast so it's probably not the best idea to hop the starters. Otherwise, that's the procedure that I would also follow if I would freeze wort. Concentrating it is a good idea to max out available space in the freezer to omit colliding with the boss of the house and her weird idea that the freezer is supposed to be holding food.

I do my starters on the stove top. I grind pale malt with 30% oats for yeast health, weigh portions for 2l of 1.04 og, Keep them and make the starter wort on the stove top when needed. No hops in there, doesn't go sour, I've tried it. Also, pale wort beer tastes funny without hops. Not exactly bad, but a bit weird. I've even carbonated it once...

 

[IslandLizard]

Hops stress yeast so it's probably not the best idea to hop the starters. [...] No hops in there, doesn't go sour [...]

I read somewhere that (low) hopping (starter) wort prevents, or at least slows, lactobacillus from growing. After diluting the concentrated wort to starter gravity (1.037) it has only around 20 IBU. I've not noticed that level impacting yeast growth, but maybe doing a side by side can shine some light on it.

I grind pale malt with 30% oats for yeast health

Interesting, I wasn't aware of oats helping with that. Unsaturated fatty acids perhaps?

Ah, I found a link to Scott Janish's research:
http://scottjanish.com/case-brewing-oats/

 

[Miraculix]

I read somewhere that (low) hopping (starter) wort prevents, or at least slows, lactobacillus from growing. After diluting the concentrated wort to starter gravity (1.037) it has only around 20 IBU. I've not noticed that level impacting yeast growth, but maybe doing a side by side can shine some light on it.


Interesting, I wasn't aware of oats helping with that. Unsaturated fatty acids perhaps?

Ah, I found a link to Scott Janish's research:
http://scottjanish.com/case-brewing-oats/

Yes, Scott was the reason I started doing that.

Regarding hops, I think they actually boost mutation rates which is not so nice. And what low rates also do is that they train the few lactos that manage to still multiply in hops influence, to tolerate hops. So what you might end up with is lacto stains that are pretty hop tolerant. That's also not so nice. It's probably not a game changer but I keep hops out of my starters.

 

[bwible]

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.

How long do you process mason jars of wort? I know different things say different times. We’ve done pickles and tomato sauce. Each of those says boil for different times.

 

[bwible]

If you’re lazy they make this canned wort you can buy and use to make starters. I have a couple of these on hand.

https://www.morebeer.com/products/o...MIwqSe_NCziQMVFUT_AR3r9g6cEAQYASABEgKp9vD_BwE

 

[rlrohan]

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.

I agree with safe canning practices but Botulism needs the proper environment to grow. It's not going to grow in the freezer. If the wort was water bath canned and stored at room temperatures then the concern for Botulism is real especially if the ph is too high. We blanch and freeze fruits and vegetables all the time, so if Botulism could grow in the freezer we would all be dead.

Just my observations from the real world, no disrespect intended.

 

[bwible]

This is another article:

https://www.homebrewtalk.com/threads/maintaining-a-healthy-yeast-bank-long-term.678997/

 

[khannon]

How long do you process mason jars of wort? I know different things say different times. We’ve done pickles and tomato sauce. Each of those says boil for different times.

Honestly, I don't know. My wife is the one with all the canning skills, I just fill the jars and fit the lids.. I'll ask her though.

 

[Bassman2003]

I agree with safe canning practices but Botulism needs the proper environment to grow. It's not going to grow in the freezer. If the wort was water bath canned and stored at room temperatures then the concern for Botulism is real especially if the ph is too high. We blanch and freeze fruits and vegetables all the time, so if Botulism could grow in the freezer we would all be dead.

Just my observations from the real world, no disrespect intended.

No disrespect taken as I posted the best practice. Other avenues will be taken from that for sure. One can not argue with the best practice, only choose to deviate from it. What's important to me is boiling does not kill the spores & microbiology often seems to find a way. Throw in some laziness and unexpected behavior then suddenly there is risk.

People gonna do, but in a forum environment, I believe it is important not to overly discuss less than safe procedures. New brewers might read this and take more liberties and be in a dangerous situation. For example: What if a no chill brewer decided to start freezing their wort? Then when they thawed the wort and put some yeast on it, maybe the yeast could be old and not drop the pH. After a few days they add more yeast and pitch the starter. Safe or not?

If they pressure canned there would be zero risk.

 

[rlrohan]

No disrespect taken as I posted the best practice. Other avenues will be taken from that for sure. One can not argue with the best practice, only choose to deviate from it. What's important to me is boiling does not kill the spores & microbiology often seems to find a way. Throw in some laziness and unexpected behavior then suddenly there is risk.

People gonna do, but in a forum environment, I believe it is important not to overly discuss less than safe procedures. New brewers might read this and take more liberties and be in a dangerous situation. For example: What if a no chill brewer decided to start freezing their wort? Then when they thawed the wort and put some yeast on it, maybe the yeast could be old and not drop the pH. After a few days they add more yeast and pitch the starter. Safe or not?

If they pressure canned there would be zero risk.

I agree with the pressure canned way. The temp is high enough in that process to kill Botulism and it is not in water bath canning. But if the water bath canned wort is stored in the freezer and thawed properly it would be safe. As for the situation "What if a no chill brewer decided to start freezing their wort? Then when they thawed the wort and put some yeast on it, maybe the yeast could be old and not drop the pH. After a few days they add more yeast and pitch the starter. Safe or not?", No I don't think it would be safe. In fact I believe there is a great risk in "no chill" and also I believe there is a great risk for all brews if the yeast doesn't start in a timely manner. Not just if canned frozen wort is used.

 

[dhoyt]

I did my first batch for the yeast bank yesterday. Things I noted and also questions... I apologize ahead of time for my ignorance.

It seems that you need about a full 1 - 1.5 L starter to get the amount of slurry you need to do 10 - 15 mL tubes. I realized this after I did a 1.5 L starter for my upcoming batch and only had about 100 mL of slurry. So next time I will overbuild... So I would like to have a general idea of the amount of yeast is in each tube for using them for starters later. That being said if I use a yeast calc and it say a 1.5 l starter will yield 212 billion cells which is calls out as 9 billion cells per mL that is the full volume of the starter correct? So if I decant all of the wort from the top of my flask and what is left of slurry is 100 mLs then the count would be 2.12 billion cells per mL right? Only thing is that math doesn't seem to math. 9 million cells per mL in 1.5 L isn't 212 billion cells. So obviously I am not looking at this or thinking about this properly. What exactly am I missing here? I am using brewfather by the way.

Other question - Is there not much concern about the yeast setting in the cryo liquid before freezing? I noticed when I checked them today that there was pretty good amount of separation.

 

[Tony B]

I did my first batch for the yeast bank yesterday. Things I noted and also questions... I apologize ahead of time for my ignorance.

It seems that you need about a full 1 - 1.5 L starter to get the amount of slurry you need to do 10 - 15 mL tubes. I realized this after I did a 1.5 L starter for my upcoming batch and only had about 100 mL of slurry. So next time I will overbuild... So I would like to have a general idea of the amount of yeast is in each tube for using them for starters later. That being said if I use a yeast calc and it say a 1.5 l starter will yield 212 billion cells which is calls out as 9 billion cells per mL that is the full volume of the starter correct? So if I decant all of the wort from the top of my flask and what is left of slurry is 100 mLs then the count would be 2.12 billion cells per mL right? Only thing is that math doesn't seem to math. 9 million cells per mL in 1.5 L isn't 212 billion cells. So obviously I am not looking at this or thinking about this properly. What exactly am I missing here? I am using brewfather by the way.

Other question - Is there not much concern about the yeast setting in the cryo liquid before freezing? I noticed when I checked them today that there was pretty good amount of separation.

You seem to be on the right track. I would say that if you’re planning to use the majority of your starter for a batch and make vials of the remainder, you should overbuild your starter. I only have a 2L flask, which is why I generally make a 1.5L starter and depending on batch requirements, I sometimes only get 4-6 vials out of the remainder. You could also take the remainder from what your batch requires and make a second starter from which to make vials.
I’m still learning as I go. One thing I have learned is propping up a lager yeast from a vial will require a large starter or a two step.
I hope this helps.

 

[dhoyt]

You seem to be on the right track. I would say that if you’re planning to use the majority of your starter for a batch and make vials of the remainder, you should overbuild your starter. I only have a 2L flask, which is why I generally make a 1.5L starter and depending on batch requirements, I sometimes only get 4-6 vials out of the remainder. You could also take the remainder from what your batch requires and make a second starter from which to make vials.
I’m still learning as I go. One thing I have learned is propping up a lager yeast from a vial will require a large starter or a two step.
I hope this helps.

Yeah I'm thinking 10 vials might be too many really. I think doing 5 should be sufficient and give me more room for a better variety of yeast strains. Do you have any thoughts on the yeast count / calculations? I seem to be missing something with that.

 

[Tony B]

Yeah I'm thinking 10 vials might be too many really. I think doing 5 should be sufficient and give me more room for a better variety of yeast strains. Do you have any thoughts on the yeast count / calculations? I seem to be missing something with that.

I use… http://www.brewunited.com/yeast_calculator.php
For calculations. But they’re really just guesstimates.
There are methods for getting a more accurate estimate. I think they require a microscope and slides. I haven’t gone that deep.

 

[schuchdan]

I have heard it is about 2 billion cells per ml. of well compacted yeast cake

 

[beren]

This thread is pinned now .

It really deserves it.

I’ve been using this for the last 2 years, and I use 15ml boro tubes so I can reuse them, sterilize in a pressure cooker: https://www.homebrewtalk.com/threads/maintaining-a-healthy-yeast-bank-long-term.678997/

As a side note, more yeast to start isn’t better. It can allow more mutated yeast to multiply and form undesirable flavors. Some people use more glycerin to keep it liquid, and only take a drop out of a single vial, then start with a 5ml starter and build it up from that.

 

[dhoyt]

I’ve been using this for the last 2 years, and I use 15ml boro tubes so I can reuse them, sterilize in a pressure cooker: https://www.homebrewtalk.com/threads/maintaining-a-healthy-yeast-bank-long-term.678997/

As a side note, more yeast to start isn’t better. It can allow more mutated yeast to multiply and form undesirable flavors. Some people use more glycerin to keep it liquid, and only take a drop out of a single vial, then start with a 5ml starter and build it up from that.

I also bought boro glass tubes to reuse and limit plastic. I was curious how the caps would do being sterilized in a pressure cooker. Mine have a silicon seal in the cap I think so should be good. You have had no issues with that?

 

[Antti]

I've read about plastic tubes (seen them sold online) that can take 122°C temperature like autoclaves.

Doesn't the Boro glass tubes shatter in the freezer? When the water expands, when turning into ice.

 

[dhoyt]

I've read about plastic tubes (seen them sold online) that can take 122°C temperature like autoclaves.

Doesn't the Boro glass tubes shatter in the freezer? When the water expands, when turning into ice.

Mine are ok, there is only a total of 12 ml in it so there is enough room in there for expansion i think. The caps are plastic though so I don't know how there will sterilize in a canner but time will tell i guess. For these new ones I just soaked them starsan for a day or so, only cause I didn't get to it for that long...

 

[beren]

They are Bakelite caps, which are fine in an autoclave. The first synthetic plastic and heat safe to 285°C depending on the type. Brittle though. You’ll break more caps than vials I bet.

 

[dhoyt]

Yeast bank check in. Label wont work, which i figured. Not sure about the yeast settling but I guess we'll find out.

 

[Tony B]

Yeast bank check in. Label wont work, which i figured. Not sure about the yeast settling but I guess we'll find out.

Looks great!
I freeze mine in isopropyl alcohol, so never tried to label individual vials. I just label the ziplock bag that I put them in.

 

[schuchdan]

Same here, just zip-lock them

 

[bdoubleya]

I've been reading various methods of doing this including yours in preparation to do it myself, and noticed none of the methods seem to pay any special consideration to the starter preparation.

The starter always seems to be prepared like any other prior to pitching into beer, and your method is virtually the same as I use except I use homemade canned starter wort. I would think the starter should be prepared in a more aseptic manner, given it is to be stored long term and should remain relatively free of contamination.

Since this is for potentially long term storage of relatively pure yeast cultures, do you let the starter grow in any particular kind of environment? My concern is possible contamination of the starter, given it grows for about 48 hours in a container simply covered by a piece of foil, otherwise in the open air. Then it's put into the fridge to cold crash, where it's exposed to all of the air inside the fridge for an extended period of time as well.

I've considered pressure sterilizing the flask, and letting the starter grow in a laminar flow hood, but I can't think of a way to aseptically cold crash it.

Has anyone used any special techniques like this to grow a starter aseptically? Is this simply way more concern than is necessary?

 

[Bassman2003]

I do not think it is a huge concern as the active yeast drops the pH to low levels and the huge number of yeast cells outcompete any foreign entities.

I will say in my few years of freezing yeast I have learned that it is important to use healthy amounts of nutrient in the starters. I have had luck with Fermax but Fermaid is good too. You want to have some FAN as well as some zinc. My fermentations really improved using frozen yeast once I added the nutrients in the starter. I add the Fermax into my canned starter wort so it is ready to go out of the mason jar.

 

[bdoubleya]

Good to know, I have not been putting any yeast nutrient in my starters. I do have some Fermaid K on hand, have you been adding it prior to pressure cooking the jars? I ordered some 50mL centrifuge tubes and glycerin to give this a go!

 

[Bassman2003]

Yes, I put it in the wort before filling the mason jars prior to pressure cooking.

 

[EscapeArtistBrewing]

Yes, I put it in the wort before filling the mason jars prior to pressure cooking.

Would Wyeast Beer Nutrient Blend be a good bet? States clearly it contains zinc--not all nutrients do. Ashton Lewis of BYO rants about this: https://byo.com/video/yeast-nutrients/ and https://byo.com/mr-wizard/using-yeast-nutrients/

 

[jtgoral]

I've been reading various methods of doing this including yours in preparation to do it myself, and noticed none of the methods seem to pay any special consideration to the starter preparation.

The starter always seems to be prepared like any other prior to pitching into beer, and your method is virtually the same as I use except I use homemade canned starter wort. I would think the starter should be prepared in a more aseptic manner, given it is to be stored long term and should remain relatively free of contamination.

Since this is for potentially long term storage of relatively pure yeast cultures, do you let the starter grow in any particular kind of environment? My concern is possible contamination of the starter, given it grows for about 48 hours in a container simply covered by a piece of foil, otherwise in the open air. Then it's put into the fridge to cold crash, where it's exposed to all of the air inside the fridge for an extended period of time as well.

I've considered pressure sterilizing the flask, and letting the starter grow in a laminar flow hood, but I can't think of a way to aseptically cold crash it.

Has anyone used any special techniques like this to grow a starter aseptically? Is this simply way more concern than is necessary?

I just did a starter 3 days ago using 2 tubes with 2022 frozen Diamond Lager yeast and 1 qt of water with 100g of DMA. Today I brewed 6 gallons of Helles.
My starters need 3 days to be active. I prepare 6-7 1 qt Ball's jars and use a canning pot for 10 minutes at 10 PSI. This way I make new DMA solution after 6-7 brewing sessions.
I use a beer sanitizer for the starter flask.
I never had problem with this way of making a starter.

When I have last two tubes of frozen yeast i make 2 qt starter. Half goes to the new beer half to make next generation of the frozen yeast (usually six 15ml tubes)

 

[ba-brewer]

1 qt Ball's jars and use a canning pot for 10 minutes at 10 PSI.

I'm not an expert but that does not seem like enough time or pressure to make your wort sterile. i think you need to get to 15psi for 20 to 30mins.