Frozen yeast bank procedure

[Broothru]

The only thing I will disagree with in his canning video is letting the canner sit overnight. I open the lid after the plug goes down which takes 30min to 1 hour. Why? You want a rapid cool for the jar lids to seal well. When I take the mason jars out the liquid is still boiling. When they sit out of the canner they cool quicker and the lids pop with a strong seal. His way might work but I have had better luck going with the way the Presto manual states.

All true, and totally correct.

One small nit to pick, however. Use extreme caution when removing the lid. Take the weights off the vent pipe (after waiting at least :30 minutes; preferably an hour) and ensure all steam has had a chance to vent out. You want to allow the pressure and temperature to dissipate slowly. Otherwise you risk shattering the glass jars. Only then should you rotate the lid to disengage the lugs so that the lid can be removed. Also, the jars will still be quite hot. All that liquid, both inside and outside the jars, will retain a lot of that 120C/250F heat for a long time. I always use a pair of Mason Jar tongs to lift and place them on a cooling rack. And you're right: once exposed to the ambient air, those lids will start popping and sealing shut just like pop corn popping on a campfire.

That was a very comprehensive video that covered all the high points, but might have come up just a little bit short on emphasizing the not-so-obvious dangers of working with pressurized fluids that have been super-heated.

 

[EscapeArtistBrewing]

...And you're right: once exposed to the ambient air, those lids will start popping and sealing shut just like pop corn popping on a campfire.

OK @Broothru and @Bassman2003, you convinced me, and I'm going to try bringing those jars out sooner and cool on the countertop (on a rack, of course; a nice cold granite top is just inviting thermal shock). When I water-bath-can jams, spreads, and other goodies, I always enjoy those satisfying "pops" as each jar's lid pulls down. I'm ready to try it with the wort--and perhaps save some time....

 

[Bassman2003]

It is too involved of a procedure to cover in a post, but I never mentioned rapid removal of the jars. It takes up to an hour for the lid to drop the plug thing (don't know the term). After that you can cautiously and safely remove the lid. I handle the jars a little as possible and remove them with the special tongs and let them sit on a towel until the next morning. The difference being the faster cooling being outside of the pressure canner.

If I make my wort in the morning (all grain) I can usually get 3 rounds of 7 - 1.080 quart mason jars run through. Enough for a year plus of starters.

 

[EscapeArtistBrewing]

I never mentioned rapid removal of the jars.

Sorry, @Bassman2003, misquoted "rapid cool down" and used "rapid removal". Sorry about that!
BTW, I didn't realize you do the Integrity Homebrewing channel. Great stuff there.

 

[Bassman2003]

Thanks! I was going to make a video about canning wort but thought better of it. There are more qualified representatives of proper canning technique on the interwebs and I am best to stay in my small lane!

When I first started canning I let the finished batch sit longer and my 'poor seal' rate was about one per batch. Now it is pretty much nil.

 

[matt_m]

Here's my first try just prior to stuffing them in a ziploc.. This is some 1010 I harvested from a batch of a wheat I just made. I still made a starter with the harvest.

I was a bit surprised at the separation between the yeast and water and presumably glycerin mix.

 

[Broothru]

Here's my first try just prior to stuffing them in a ziploc.. This is some 1010 I harvested from a batch of a wheat I just made. I still made a starter with the harvest.

I was a bit surprised at the separation between the yeast and water and presumably glycerin mix.

View attachment 871205

Looks just like mine, down to the centrifuge tubes and blue caps. I'm not sure that the samples ever 'freeze' the same way we think of things freezing in retail refrigerators. Lately I've started using breast milk freezing bags for storage. They hold about 150 ml, so roughly 3x as much as those tubes. Even after several weeks of storage in my beer fridge freezer compartment (~24-28F), the "equal parts 30% glycerin/70% distilled water mix to yeast slurry" has the viscosity of a Slurpee from 7-11. It must work though, since I revived a three year-old frozen sample a month ago. Just chucked the whole thing into 500 ml starter yeast, hit it with O2, spun it on the stir plate for five minutes, and had a nice colony of yeasties ready to go in a few days.

 

[pvpeacock]

I ended up buying the 30 ml tubes so I only need one per 1 ltr. starter.
https://www.amazon.com/dp/B0C3RSNNP4?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_4&th=1

 

[matt_m]

I should say, I froze this in a container of alcohol like the OP suggested. Next up I've got a 3rd generation starter going from 1/3 of a starter I made from a pack of Imperial A07 I did in late January.

I've looked at canning wort and struggle with the idea of that saving time since everything I've read says to boil the water used to dilute it. My starter process has gotten pretty quick. I run 1500ml of RO water into the clean flask while getting out my induction hot plate and starter pot and adding a cup of DME to the pot. I dump the water in, whisk it well, add a couple drops of fermcap and a 1/2 teaspoon of nutrient while heating, then put the flask, foil, funnel, and stirbar in my Starsan bucket.

I have a bucket in my brewery with one of those "grit guard" things for car washing that I fill with water above the grit guard to about the level of the wort in the flask. This gives some extra water volume to absorb more heat.

When the starter is done boiling for 10 minutes, I immediately dump the wort into the sanitized flask with the sanitized funnel. and cover with the sanitized foil and place in the bucket. At 30 minutes its at pitching temp and I add the yeast and put the stir plate for ~2 days.

This takes 15 minutes or so beside the 30 minute cooling time. I can easily do this at lunch, or between meetings

 

[redrocker652002]

Man I really want to try this, but I don't have freezer space for the tubes (read into that, the wife is the keeper of the freezer).

 

[Bassman2003]

I've looked at canning wort and struggle with the idea of that saving time since everything I've read says to boil the water used to dilute it.

I buy bottles of water or even gallons of water to dilute my pressure canned wort.

 

[pvpeacock]

I just use carbon filtered tap water to dilute the canned wort and have never had a problem.

 

[matt_m]

I just put another 15 vials in the freezer, this time L05 Cablecar that was getting pretty old. Overkill but I bought a cheap auto pipettor that made the process a lot quicker.

 

[Shenanigans]

Thanks for this tutorial.
It's only the water/glycerin mixture that you are sterilizing with heat/steam?
The other components - vials etc. are just being sanatized in StarSan or something similar?

 

[Tony B]

Yes. I use new vials and soak them in starsan solution while I’m getting everything ready. I use new, sterile syringes and then toss them. Basically, anything that may touch the yeast slurry is soaked or sprayed with starsan solution.
This has worked well for me, but I would say deeper sanitizing or sterilizing is never a bad thing.

 

[Shenanigans]

Yes. I use new vials and soak them in starsan solution while I’m getting everything ready. I use new, sterile syringes and then toss them. Basically, anything that may touch the yeast slurry is soaked or sprayed with starsan solution.
This has worked well for me, but I would say deeper sanitizing or sterilizing is never a bad thing.

Ok, thanks for explaining.

 

[ClaudiusB]

Yes. I use new vials and soak them in starsan solution while I’m getting everything ready. I use new, sterile syringes and then toss them. Basically, anything that may touch the yeast slurry is soaked or sprayed with starsan solution.
This has worked well for me, but I would say deeper sanitizing or sterilizing is never a bad thing.

I use only pre-sterilized vials, but I have autoclaved some used once.

 

[Tony B]

Ok, thanks for explaining.

I haven’t tried to update the written process since I started this thread, almost a year ago. I now use a two step starter for propping up all of my frozen vials.
I first boil a ~250ml, 1.025 starter in my flask. Once the wort is cooled and the vial thawed, I pitch and put it on the stir plate for about 48 hours.
After that I boil 1-1.25L of 1.037 wort. After it’s cooled to room temp, I use a sanitized funnel to add it to the flask. I let that work for another 48+ hours until I’m ready to brew.
I feel this is less stressful on the yeast and has worked very well for me.

 

[Brockness Monster]

Are you still doing it with 6mL slurry and 6 mL glycerin/water mixture?

I am thinking about picking up a pressure canner that should be big enough to sterilize the glycerin/water mixture and 10 polypropylene vials, may be able to add a jar of water and dme mixture or 2.

 

[Tony B]

Are you still doing it with 6mL slurry and 6 mL glycerin/water mixture?

I am thinking about picking up a pressure canner that should be big enough to sterilize the glycerin/water mixture and 10 polypropylene vials, may be able to add a jar of water and dme mixture or 2.

Yes. Thats my go to amount to keep from over filling and leave a little head room for expansion in the 15ml vials.
Your plan for the pressure canner sounds great. Let us know how it works out.

 

[Miraculix]

Boiling the mix or heating it up to about 80c should suffice perfectly.

We are dealing with a non - sterile medium here that has loads of other microbes in it, the yeast slurry. And that's fine as long as the other microorganisms are in a manageable amount. We won't shift that amount in any meaningful way by autoclaving anything that's in contact with it. Star San is enough.

If we would be working with yeast directly from the pouch within a lab environment with filtered air, then autoclaving would be meaningful. In this context here, it's not.

 

[Shenanigans]

One more question, can I use Bio Ethanol instead of the Isopropyl Alcohol?
Apart from the fact I already have a bottle of Bio Ethanol here, it is generally more readily available if I need to get more, cheaper and safer for human consumption should some of it shomehow happen to get into one of the vials or subsiquent starters.
It does however freeze at lower temperatures (114oC vs 89oC) so maybe that makes the Isopropyl Alcohol more suitable?
I can't see why though.

https://www.oculyze.net/bioethanol-vs-isopropyl-alcohol-what-are-the-differences/

 

[Bassman2003]

Boiling the mix or heating it up to about 80c should suffice perfectly.

We are dealing with a non - sterile medium here that has loads of other microbes in it, the yeast slurry. And that's fine as long as the other microorganisms are in a manageable amount. We won't shift that amount in any meaningful way by autoclaving anything that's in contact with it. Star San is enough.

If we would be working with yeast directly from the pouch within a lab environment with filtered air, then autoclaving would be meaningful. In this context here, it's not.

Good points. At our level, clean is as important or more important than sterile. While we can not see it, we are managing populations of unwanted organisms through our process in spite of our environment. Keep everything super clean and limit exposure to air is about the most we can do. Yes, sanitizers and pressure cookers are part of it but the little mistakes can ruin all of the sanitizer's impact.

 

[Miraculix]

Good points. At our level, clean is as important or more important than sterile. While we can not see it, we are managing populations of unwanted organisms through our process in spite of our environment. Keep everything super clean and limit exposure to air is about the most we can do. Yes, sanitizers and pressure cookers are part of it but the little mistakes can ruin all of the sanitizer's impact.

I think I might have said it in a way that can be easily misunderstood. Autoclaving is in this case the same as using a pressure cooker. It's simply unnecessary within our environment. Pasteurizing, maybe boiling and of course being very clean and sanitised is enough for the works that we are doing within the usual home brewers environment. Not counting storage of fresh wort, that would need to be autoclaved.

 

[Bassman2003]

I think you were clear/right both times. It is my opinion that cleaning is kind of left out of the whole sanitizing discussion in the homebrew world. Bad things need to grow to be harmful. If surfaces are clean, there is very little to fuel that growth outside of the medium like wort. A simple splash of sanitizer will be effective. If something is not truly clean, then no amount of sanitizer will be effective. So from my perspective, cleaning holds more of the cards.

 

[Miraculix]

I think you were clear/right both times. It is my opinion that cleaning is kind of left out of the whole sanitizing discussion in the homebrew world. Bad things need to grow to be harmful. If surfaces are clean, there is very little to fuel that growth outside of the medium like wort. A simple splash of sanitizer will be effective. If something is not truly clean, then no amount of sanitizer will be effective. So from my perspective, cleaning holds more of the cards.

Yep, that's the main point! And in addition, in dirt, nasties can stay untouched by the sanitizer and get into the wort.

 

[elproducto]

Pretty happy. My first time propping up my frozen yeast and it worked awesome.

6ml of LAIII. I pitched into a 250ml starter to get it going and then used a 1200ml. This pic is only 48 hours after pulling it from the freezer!

Thanks @TonyB for the guide.

 

[Tony B]

I’m really glad that this has become a space for all of us frozen yeast bankers to share knowledge and pass on our experiences.

 

[pvpeacock]

Just revived some WLP 007 Dry English Ale yeast from November 2023. It took a few days to show signs of fermentation in the starter, but was chugging away by the time I pitched it into a fermenter of English IPA.

 

[Skeeter686]

One more question, can I use Bio Ethanol instead of the Isopropyl Alcohol?
Apart from the fact I already have a bottle of Bio Ethanol here, it is generally more readily available if I need to get more, cheaper and safer for human consumption should some of it shomehow happen to get into one of the vials or subsiquent starters.
It does however freeze at lower temperatures (114oC vs 89oC) so maybe that makes the Isopropyl Alcohol more suitable?
I can't see why though.

https://www.oculyze.net/bioethanol-vs-isopropyl-alcohol-what-are-the-differences/

I'm not an expert (I've only done this one so far!) but I'm pretty confident that the Bio Ethanol should be fine, as long as it's pure enough to prevent freezing when it's in the freezer.

My understanding is that the alcohol is only there to ensure a slower, even freezing process for the yeast. If the liquid that you're using to accomplish this were to freeze, then you wouldn't be able to get the vials out, which is presumably why alcohol is recommended.