Guide to Making a Frozen Yeast Bank

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thepipesarecall said:
Alright so I baked the vials with the glycerin/water solution in them and lost about 1/3 the volume, not a problem as I overfilled them (in the proper ratio) to accomodate for this. My only issue is that it appears the white seal under the caps has disfigured under the heat, will this present a program for long term storage? Also, is a freezer-safe thick Rubbermain container satisfactory for freezer storage?

Yeah, melted caps will be a problem. Is the rubbermade container insulated?

Also, you no longer have a solution in the same ratio you originally had, because everything that boiled off was straight water.
 
Alrighty then, I suppose I'll try the baking method again, sealing the vials this time to prevent damage to said seal, although it may crack the vials as you said MalFet.

The container is not insulated (neither the grocery store or CVS had the zippered/insulated boxes), but it is made of some fairly thick plastic, says Freezer Safe on the bottom?
 
Alrighty then, I suppose I'll try the baking method again, sealing the vials this time to prevent damage to said seal, although it may crack the vials as you said MalFet.

The container is not insulated (neither the grocery store or CVS had the zippered/insulated boxes), but it is made of some fairly thick plastic, says Freezer Safe on the bottom?

If the seals melted when the vials were open, there's no reason to think they won't melt again when closed.

Tupperware plastic is typically a fairly poor insulator. Put some hot water into it and see how long it takes for the exterior to warm up.

I wish you luck, but you aren't the first person who tried to come up with an alternative to the pressure cooker. To my knowledge nobody has been successful. The cost of bake-safe sealable vials in any quantity is quickly going to outstrip the $30 a pressure cooker will cost you. If you don't pay your own utility bills, tyndallization might be cost effective. But, going that route, I'd want to plate out a few samples to make sure I was actually seeing true sterility.
 
I know I'm coming in late to the game, but I've been using a slightly different technique that has saved some time, although requires different equipment. I happened to have a large pack of sterile 10mL vacutainers and an inoculation gun kicking around, so I poured about 35 mL of glycerin into a few flasks, tossed those in the pressure cooker, cooled off, then poured the contents of a Wyeast smack pack into each one. After a hearty shake (and a good shake after every pump to keep it well mixed), I dialed the gun down to 9mL per actuation and started the process, only takes a few minutes to fill about 16 vials per pack. 2 days in the fridge, then a good shake and into the freezer they go. I've had extremely vigorous fermentation with every tube I've used (thaw in the fridge for a day, pitch to a 250 mL starter/stir plate for a day, then to a 1L starter for a day or two), and no contamination issues as of yet. The only issue I've had so far is that, if I don't tape up the stopper when I thaw, the back pressure will pop it off in the fridge.
 
I can't think of any reason this would be a problem, other than being bulkier to store. That said, if you've already got the big tubes, why not use more solution and slurry?

Great thanks. I'll move down to smaller tubes when I need more but I have 30+ so might be a while.
 
One thing I don't understand, why Starsan is enough to SANITIZE EVERY STEP of the beer making but won't cut it when it comes to yeast storage? Also, if Glycerin sold in pharmacies, shouldn’t it be sterile or clean enough(USP grade) to suffice right out of a container? :confused:
Think this, we can easily store bottled beer for a year in cool or fridge temp, but CAN’T store yeast FROZEN with the same sanitizing technics for the same amount of time? I don't want to offend anyone, just trying to think logically. :mug:
 
maxoldo said:
One thing I don't understand, why Starsan is enough to SANITIZE EVERY STEP of the beer making but won't cut it when it comes to yeast storage? Also, if Glycerin sold in pharmacies, shouldn’t it be sterile or clean enough(USP grade) to suffice right out of a container? :confused:
Think this, we can easily store bottled beer for a year in cool or fridge temp, but CAN’T store yeast FROZEN with the same sanitizing technics for the same amount of time? I don't want to offend anyone, just trying to think logically. :mug:

It is an issue of proportions. StarSan does not kill everything, but thats okay in general brewing circumstances. A small population of bacteria won't be able to spoil a beer if it is vastly outnumbered by a large population of yeast. It gets out-competed, and ends up in a stressful high alcohol environment before it has a chance to bred to sufficient numbers.

When freezing, however, we're dealing with small numbers of yeast cells being stored for a long time. If the yeast doesn't get a sufficient head-start, even a relatively small initial bacteria population can proliferate.
 
It is an issue of proportions. StarSan does not kill everything, but thats okay in general brewing circumstances. A small population of bacteria won't be able to spoil a beer if it is vastly outnumbered by a large population of yeast. It gets out-competed, and ends up in a stressful high alcohol environment before it has a chance to bred to sufficient numbers.

When freezing, however, we're dealing with small numbers of yeast cells being stored for a long time. If the yeast doesn't get a sufficient head-start, even a relatively small initial bacteria population can proliferate.

But isn’t it the same for a vial? If the ratio of vial mix is 50% yeast, 25% water and 25% glycerin, wouldn’t this be true to these proportions?
Just imagine a fermenter half-full of pure yeast, what chance of survival a tiny colony of nasty bacteria has?
 
It is an issue of proportions. StarSan does not kill everything, but thats okay in general brewing circumstances. A small population of bacteria won't be able to spoil a beer if it is vastly outnumbered by a large population of yeast. It gets out-competed, and ends up in a stressful high alcohol environment before it has a chance to bred to sufficient numbers.

When freezing, however, we're dealing with small numbers of yeast cells being stored for a long time. If the yeast doesn't get a sufficient head-start, even a relatively small initial bacteria population can proliferate.

plus bacteria grow much faster than yeast and generally withstand freezing better. Therefore when thawing, if you have a tiny bit of bacteria compared to a larger amount of yeast, the bacteria can take off quicker with exponential growth. When you pitch into your 5 gal of wort, you pitch several folds more yeast that are already primed to grow as opposed to ones that are coming out of freezing
 
maxoldo said:
But isn’t it the same for a vial? If the ratio of vial mix is 50% yeast, 25% water and 25% glycerin, wouldn’t this be true to these proportions?
Just imagine a fermenter half-full of pure yeast, what chance of survival a tiny colony of nasty bacteria has?

The fact that StarSan isn't sufficient for freezing is relatively easy to demonstrate, and I'd encourage you to plate some samples if you're still not convinced. Without real sterilization, they get green and fuzzy fast.

The problem with your analogy (I suspect) is that yeast populations grow linearly with total volumes (2L of slurry has twice the cell count of 1L of equivalent slurry), but errant bacteria populations are more complicated because bacteria is typically growing on organic soils. A little blob of non-visible gunk might have a few hundred million bacteria in it, regardless of whether it's in a 20L carboy or in a 1mL microtube.
 
Just imagine a fermenter half-full of pure yeast, what chance of survival a tiny colony of nasty bacteria has?

100%. Every batch of beer made (aside from laboratory propgation) has bacteria in it. My beer has some, your beer has some, and the beer from every commercial brewery has some. The important part in brewing is keeping things sanitary (mostly free from bacteria) to ensure those bacteria do not build up enough numbers to affect the final product (no more than 1000 bacteria/mL from what I read). Remember that unpasteurized unfiltered beer usually has at least 1,000,000 yeast cells/mL

When you are propagating yeast from such a small number (anything less than 1 billion cells really) the problem is that you will also grow the bacteria/other contaminants to extreme levels, enough to affect the final beer. If steam pressure sterilization was not necessary then microbiologists the world over would not be spending megabucks and megatime on sterility. We go through the effort because it is needed. Period.
 
Now I’m convinced. Thank you all for input! :)
Is there a way to avoid buying a pressure cooker? Will a baby bottle sterilizer do(Philips AVENT Digital Steam Sterilizer)?
My SWMBO hates messy kitchen and since we already have that sterilizer sitting on the countertop she won’t mind me using it instead of buying another gadget for my new beer making hobby(read obsession) :mug:
 
maxoldo said:
Now I’m convinced. Thank you all for input! :)
Is there a way to avoid buying a pressure cooker? Will a baby bottle sterilizer do(Philips AVENT Digital Steam Sterilizer)?
My SWMBO hates messy kitchen and since we already have that sterilizer sitting on the countertop she won’t mind me using it instead of buying another gadget for my new beer making hobby(read obsession) :mug:

In a word, no. Unpressurized steam just doesn't get hot enough before it blows away. Some people have experimented with a process called tindalization, but it is tedious and gets mixed reviews for efficacy.
 
try hitting up craigslist or consignment store. I found a brand new 19qt presto pressure cooker for $45. On my way to pick it up someone beat me 2 it. I should have asked for it to be help. Worst decission ever!

either way I have had one for a year now and just started cooking chicken in it. It is sooo fast and good. I cook chicken in 8 min and it cost me $0.80 per chicken quarter. More savings = more beer! W0oT
 
I'm getting a pressure cooker today! :rockin:
I have washed some yeast from the last couple of batches, do I make starters first from those before freezing, to make sure yeast is active and healthy, or do I just collect yeast slurry and put it in vials with glycerin/water solution? Also, how can I check it’s not contaminated, do I just smell and taste the starter?
 
I'm getting a pressure cooker today! :rockin:
I have washed some yeast from the last couple of batches, do I make starters first from those before freezing, to make sure yeast is active and healthy, or do I just collect yeast slurry and put it in vials with glycerin/water solution? Also, how can I check it’s not contaminated, do I just smell and taste the starter?

Make a starter. If you are planning to freeze for any significant period of time, it'll be good to have healthy yeast going in.

Contamination can be tough to test, but tasting your starter steps for perceived changes is a good bet. Beyond that, you'd have to plate out individual colonies.
 
Hey sorry if it's been addressed I read pages 1-25 on the thread earlier and searched a bit. My question is this. I filled my jars to wash yeast with tap water and capped them in ball jars then boiled them. Will this water kill my yeast if I wash with it? My tap ph is 8ish and I don't have a way to test further for chlorine/ chloramine in my tap water. I've been RDWHAHB and I don't want to kill this awesome cake. Will my sanitized tap water kill the pacman yeast I've got a nice cake of? Thanks. B
 
bojacked said:
Hey sorry if it's been addressed I read pages 1-25 on the thread earlier and searched a bit. My question is this. I filled my jars to wash yeast with tap water and capped them in ball jars then boiled them. Will this water kill my yeast if I wash with it? My tap ph is 8ish and I don't have a way to test further for chlorine/ chloramine in my tap water. I've been RDWHAHB and I don't want to kill this awesome cake. Will my sanitized tap water kill the pacman yeast I've got a nice cake of? Thanks. B

Are you planning to freeze the yeast?

If so, you might be fine, but it would be much safer to use a pressure cooker to sterilize properly.

If you aren't planning to freeze, this isn't really the right thread for your question, so if you have follow-ups you should head over to the yeast washing thread. That said, boiled water should be sufficiently sanitized.
 
Hey Malfet, I neglected to mention that the whole point of this was to freeze the yeast so I can store them for a long time.
 
Well, I just want to warn all of you to something MalFet told me earlier that he was correct on....

ALWAYS USE A PRESSURE COOKER. I attempted to grow some yeast out of a bottle of gavroche french red ale that I got and that worked out great. But I only used star san when putting the yeast into vials with the glycerin, and did not sanitize the glycerin, and now I have attempted to re-grow the yeast... EVERY vial has a bacterial infection.

I have about 5 other yeasts frozen besides that one at the moment, and they all came back just fine, but on all of them I used the pressure cooker.

It's not worth the risk, they are cheap and easy to use, just get one and use it!

Note that I've found that cooking the wort to use for your first step up starter (from the vial) in a pressure cooker has been pretty handy in making sure the yeast grow and nothing else, and make sure that you put that glycerin in the vials when you put them in the pressure cooker so its sterilized as well before you put yeast into the vials.
 
I've been starsan-ing everything with great results. I do need to invest in a pressure cooker the more I use my glycerin I suppose.
My yeast's activity tends to be unnoticeable for the first day or two of starter fermentation. But by the third day things are always going great.
 
I've been starsan-ing everything with great results. I do need to invest in a pressure cooker the more I use my glycerin I suppose.
My yeast's activity tends to be unnoticeable for the first day or two of starter fermentation. But by the third day things are always going great.

If you are plating out your samples and getting pure cultures with just StarSan, more power to ya. There are enough counter-examples, though, to suggest that you are just getting lucky. If you are not plating them out, what makes you think your samples are pure? In any case, best practices call for sterilization, which starsan does not provide.
 
What do you recommend to transfer the yeast? I bough a 10 mL Mohr pipette, but the opening is too narrow to suck up yeast slurry. I'm thinking about getting a stainless turkey baster with a screw-on needle tip, but the bulb is probably not autoclavable.
 
orangehero said:
What do you recommend to transfer the yeast? I bough a 10 mL Mohr pipette, but the opening is too narrow to suck up yeast slurry. I'm thinking about getting a stainless turkey baster with a screw-on needle tip, but the bulb is probably not autoclavable.

Many people use medical syringes with good results. They're cheap and generally auto-clavable.
 
All pipette tips are large enough to pick up slurry. Hop bits and assorted trub may clog the tips, but the yeast will get through just fine.
 
Thundercougarfalconbird said:
Bought an auto-pipet with pyrex tubes. I think its the best way to go about it as far as extracting yeast/glyerine

What model and from where if you don't mind?
 
Are there any larger autoclavable vials than in the op? I'd rather not have to do two starters to get a frozen vial ready to pitch.

Or would a well stirred starter on a stirplate with one of these vials allow for good propagation?
 
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