best sealed vials for freezing yeast

[NeverDie]

I read this how-to: https://www.homebrewtalk.com/freezing-yeast.html
but all the links it had for freezer test tubes are broken links.

What should I look for? I found these:
https://www.amazon.com/gp/product/B01J43JF3Q/?tag=skimlinks_replacement-20
which sound appealing because they are advertised as already sterile and the seller says in the Q&A that they are "hermetically sealed" down to -30 degrees. But then that's the seller saying that, not the manufacturer per se, so it's not completely re-assuring. I obviously don't want the yeast slurry to evaporate in the freezer over time (like cubes in a forgotten ice cube tray do), so I thought I'd ask if others here have found good vials that do the business and that they are happy with.

 

[z-bob]

I have a bunch of these already: https://www.amazon.com/gp/product/B01FIFCDGK/?tag=skimlinks_replacement-20 I don't know what kind of plastic they are made of, but I'm going to give them a try. Glass is probably better, OTOH these are shatterproof if you drop them.

 

[dx250]

I use a different brand but these are the equivalent cryogenic vials.


Globe Scientific CryoClear 3015-50 Polypropylene Barcoded Cryogenic Vial, 5mL Capacity, Sterile, External Threads, Attached Screwcap with Molded O-Ring, Round Bottom, Self-Standing (Case of 50) https://www.amazon.com/dp/B00G6SL3ZQ/?tag=skimlinks_replacement-20

 

[sDriver]

I read this how-to: https://www.homebrewtalk.com/freezing-yeast.html
but all the links it had for freezer test tubes are broken links.

Technically the links are just mostly broken. Looks like the site wrapped stuff around the original. If you look at the link location of the posted links in notepad - you can get the original working link:
http://www.amazon.com/dp/B0018MQ9TK/?tag=skimlinks_replacement-20

http://www.amazon.com/dp/B005Z4S3ZU/?tag=skimlinks_replacement-20

http://www.amazon.com/dp/B005CBFATS/?tag=skimlinks_replacement-20

 

[NeverDie]

I use a different brand but these are the equivalent cryogenic vials.


Globe Scientific CryoClear 3015-50 Polypropylene Barcoded Cryogenic Vial, 5mL Capacity, Sterile, External Threads, Attached Screwcap with Molded O-Ring, Round Bottom, Self-Standing (Case of 50) https://www.amazon.com/dp/B00G6SL3ZQ/?tag=skimlinks_replacement-20

5ml doesn't seem like much. I guess you're propagating it in a series of starters before pitching it?

 

[dx250]

Yeah I am doing a stepped starter, it takes about 3 days.

 

[NeverDie]

I read this how-to: https://www.homebrewtalk.com/freezing-yeast.html
but all the links it had for freezer test tubes are broken links.

What should I look for? I found these:
https://www.amazon.com/gp/product/B01J43JF3Q/?tag=skimlinks_replacement-20
which sound appealing because they are advertised as already sterile and the seller says in the Q&A that they are "hermetically sealed" down to -30 degrees. But then that's the seller saying that, not the manufacturer per se, so it's not completely re-assuring. I obviously don't want the yeast slurry to evaporate in the freezer over time (like cubes in a forgotten ice cube tray do), so I thought I'd ask if others here have found good vials that do the business and that they are happy with.

I ordered these vials and used them today. They do have screw on caps, but I'm not 100% convinced that they will seal well. I'm going to order the kind with o-rings next.

 

[z-bob]

Do they have to seal well?
https://science.howstuffworks.com/innovation/scientific-experiments/scientific-method5.htm

 

[SoCal-Doug]

I prepare and freeze my slants in kimax 16x100 glass slant tubes with screw lids. $10 to $13 for 25 of them and they are reusable. They work great. But the yeast cultures are filled with autoclaved mineral oil before freezing. Freezing yeast without glycerin or mineral oil very much shortens the storage life and decreases viability.

 

[z-bob]

Mineral oil? How does that work?

 

[SoCal-Doug]

Mineral oil? How does that work?

Agar, (kinda like a harder gelatin mixed with some DME), is poured into a test tube on an angle for more surface area (hence the term "slant") and allowed to harden. Yeast is then smeared onto the agar and allowed to grow for a few days. Then mineral oil is poured into the remaining airspace of the tube. The whole thing can be frozen for a year or two.

When needed, simply dump out the mineral oil and pour some wort into the tube and shake well. Allow to grow overnight. Dump that into a starter flask. After a few days, do another "step up" starter. Pitch it. Oh, and while you are at it, smear that starter onto a couple more slants and store them again. In short, never buy that yeast again, just keep growing it.

 

[NeverDie]

I decided to order this: https://www.amazon.com/gp/product/B00E3KIXQQ/?tag=skimlinks_replacement-20
from amazon, because the price was $30.42, which seemed like a good deal for 500 vials. The vials are small, but that also means I should be able to keep enough of the original yeast in the freezer that I'll pretty much always have a vial of generation zero available to inoculate a new stepped starter. Well, that's the hope!

For $18.06, I also ordered these freezer racks to go with it: https://www.amazon.com/gp/product/B00E3KX4YC/?tag=skimlinks_replacement-20

 

[SoCal-Doug]

I decided to order this

You went all high tech Very cool. I took a chunk of 2x4 and drilled it to hold 30 tubes. LOL

 

[NeverDie]

You went all high tech Very cool. I took a chunk of 2x4 and drilled it to hold 30 tubes. LOL

Actually, it was your post that inspired me. I just don't yet have the skill/time yet to do slats, that's all, so I tried to find something maybe easier that I could do.

 

[NeverDie]

I prepare and freeze my slants in kimax 16x100 glass slant tubes with screw lids. $10 to $13 for 25 of them and they are reusable. They work great. But the yeast cultures are filled with autoclaved mineral oil before freezing. Freezing yeast without glycerin or mineral oil very much shortens the storage life and decreases viability.

I don't have an autoclave. What do you recommend instead? If need be, I do have a pressure cooker though.

 

[z-bob]

A pressure cooker is an autoclave.

 

[NeverDie]

Oh. Well, in that case, what kind of pressure cooker setting should I use then to autoclave the mineral oil, and for how long?

 

[z-bob]

You don't need to autoclave mineral oil to sterilize it. Just heat it to... I dunno, 300 degrees. (I'm still skeptical about this whole mineral oil thing) For stuff that does need to be autoclaved, set the pressure cooker to 15 psi and give it a half hour after you purge the air and it reaches full pressure.

 

[NeverDie]

You don't need to autoclave mineral oil to sterilize it. Just heat it to... I dunno, 300 degrees. (I'm still skeptical about this whole mineral oil thing) For stuff that does need to be autoclaved, set the pressure cooker to 15 psi and give it a half hour after you purge the air and it reaches full pressure.

Using glycerin seems to be what get's talked about most in the context of freezing yeast: https://www.homebrewtalk.com/maintaining-healthy-yeast-bank-long-term.html

Oops. According to that link, "Yeast will continue to metabolize and be otherwise fairly biologically active in any environment above -20°C...." I don't think my freezer goes that low.

 

[z-bob]

Using glycerin seems to be what get's talked about most in the context of freezing yeast: https://www.homebrewtalk.com/maintaining-healthy-yeast-bank-long-term.html

Oops. According to that link, "Yeast will continue to metabolize and be otherwise fairly biologically active in any environment above -20°C...." I don't think my freezer goes that low.

-20°C isn't as cold as it sounds. About -5°F. That's what I have my kitchen freezer set to, and the deep freezer in the basement is colder but I'm not sure how much.

 

[shelbymedic]

I obviously don't want the yeast slurry to evaporate in the freezer over time (like cubes in a forgotten ice cube tray do),

That’s technically sublimation, not evaporation. [emoji51][emoji51]

 

[Kwitty]

I used breast milk freezer bags to store yeast in a glycerine solution. The bags are already steril, they have a double seal, you can write on them with a sharpie, and you can squeeze out the excess air. If you lay them flat to freeze you can then move them to a box and set them in like file cards. The bags are cheap about 100 for $15 to $18. Had good luck so far. Anybody else ever try this?

 

[NeverDie]

I'm going to trying freezing some yeast using glycerin and the new vials, which should arrive today. I'll freeze them for a few days and then see if I can revive them enough to make a solid starter.

Does the yeast need to steep in the glycerin for a period of time before freezing it, or do I freeze immediately after mixing the yeast with the glycerin?

 

[NeoBrew]

I would recommend The Yeast Book if you are going to work on yeast ranching. I've just started getting into it myself, but the book has been a really handy reference. It has complete instructions for preparing for freezing as well as slanting and plating yeast.

As for slanting with mineral oil, I don't believe that technique is meant to be frozen. According to the book, (Which I don't have in front of me right now) I believe it says a slant will keep at room temp for up to a year under mineral oil.

 

[z-bob]

As for slanting with mineral oil, I don't believe that technique is meant to be frozen. According to the book, (Which I don't have in front of me right now) I believe it says a slant will keep at room temp for up to a year under mineral oil.

That makes sense. The mineral oil wouldn't provide any protection against cell damage from freezing. It would protect it from exposure to air, and from drying out. Might be a good way to store yeast slants in a very cold (but not freezing) refrigerator.

 

[NeverDie]

I would recommend The Yeast Book if you are going to work on yeast ranching. I've just started getting into it myself, but the book has been a really handy reference. It has complete instructions for preparing for freezing as well as slanting and plating yeast.

As for slanting with mineral oil, I don't believe that technique is meant to be frozen. According to the book, (Which I don't have in front of me right now) I believe it says a slant will keep at room temp for up to a year under mineral oil.

Yeah, I have the yeast book. It diverges a bit from the homebrewtalk method of freezing. For instance, it advocates centrifuging the yeast. Apparently storing the yeast at -80C is preferable, and -20C is less than ideal, but a compromise because that's all that some people have available. It also seems to imply that a rapid freezing works better, such as by using liquid nitrogen or perhaps dry ice and ethanol. But then it also says that not all labs agree with that. So, it's a bit wishy washy.

In any case, it appears that no steeping is required. Hopefully the yeast and glycerin don't separarte. I guess that's what I'll find out when I try it.

 

[NeverDie]

It turns out that my Instant Pot doesn't get hot enough to qualify as a true autoclave. Bummer.

 

[Terpene]

I ordered these vials and used them today. They do have screw on caps, but I'm not 100% convinced that they will seal well. I'm going to order the kind with o-rings next.

Those 15 mL centrifuge tubes should seal just fine. If not, Parafilm is your friend.

PM-996 All Purpose Laboratory Film https://www.amazon.com/dp/B07JFFZY46/?tag=skimlinks_replacement-20

 

[NeverDie]

Those 15 mL centrifuge tubes should seal just fine. If not, Parafilm is your friend.

PM-996 All Purpose Laboratory Film https://www.amazon.com/dp/B07JFFZY46/?tag=skimlinks_replacement-20

Thanks for the link. I noticed that the Yeast book prescribed using parafilm regardless, but it gave no rationale as to why.

 

[NeverDie]

OK, so I got a real pressure cooker to autoclave the glycerin solution, which I did last night. And I froze some tubes overnight. As I was afraid would happen, the glycerin solution separated from the yeast, so I'm not sure how much good it did.