Do you know how to make a yeast starter? Then why not farm yeast and freeze it?

[BBL_Brewer]

Hey all,

Regarding the glycerin/water solution, is there reason to believe that this stuff would have a limited shelf life (uncanned, in the fridge)?

Basically, in preparation for harvesting yeast to freeze, I can up some 4 oz jars of 2-1 glycerin/water mixture. I then blend in the solution 4-1 in the yeast slurry which gives me around 17% glycerin. Probably close enough for government work...

Anyhow, when I'm done, I have leftover solution (by design, so as to make sure I have enough!). What I would like to do is screw the top back on the jar and stick it in the fridge, then next time I pull out the pressure canner to make starter wort or whatever, re-combine the mostly-empty jars and re-can it to sterilize it.

The stuff could potentially be sitting in the refrigerator for a couple of months.

Is there anything that would likely go wrong with it? Obviously any organisms that were in it would get killed in the canner, but is there nasty stuff that it could have grown, or is the solution too dense?

Thanks

I'm not sure what the shelf life is in the frige, but I'm guessing it won't last forever. I just toss any left over solution in the freezer and throw it in on the next batch that gets canned.

 

[ResumeMan]

I'm not sure what the shelf life is in the frige, but I'm guessing it won't last forever. I just toss any left over solution in the freezer and throw it in on the next batch that gets canned.

Oh, freezer - good idea! Thanks, that's what I'll do.

 

[mblanks2]

Subbed

 

[doublehaul]

As always, there is more than one way to skin a cat, but here’s how I do my process.

I like Wyeast so I always start with an activator smack pack. You can use whatever yeast you want. I buy one smack pack of every yeast strain I plan to use and then farm enough yeast of each to last me for about a year or a little over. I use the Yeast Calc pitching rate calculator, but you can pick the calculator of your choice (I know a lot of people like Mr. Malty). I make up an appropriately sized starter in steps so that the estimated final cell count is ~500 billion. I setlle out the yeast, siphon off the starter beer and add enough glycerine/water solution to bring the volume up to 500 milliliters (with a final glycerine contration of 20% by volume). Then I split the yeast into 5 equal portions and refridgerate them for 48 hours before freezing. If I want more jars than that of a particular strain I will take one of the portions and put it back through the process. You can do this over and over again until you have as much yeast as you want. [/url]

Sorry if this has been asked. Following your process exactly, you say "I setlle out the yeast, siphon off the starter beer and add enough glycerine/water solution to bring the volume up to 500 milliliters"

So you add glycerin mixed with water to the yeast slurry? What is the glycerine to water ratio?

 

[mliptack]

BBL mentions a 20% solution in the post. So for 100ml of solution add 20ml to 80ml H2O

Or with about 100ml of yeast slurry 80ml of glycerine to 320ml H2O. For a total volume (incl yeast) of 500ml

 

[doublehaul]

BBL mentions a 20% solution in the post. So for 100ml of solution add 20ml to 80ml H2O

Or with about 100ml of yeast slurry 80ml of glycerine to 320ml H2O. For a total volume (incl yeast) of 500ml

How I (re)read it is you want 20% total volume glycerine so ur second example would be 100ml glycerine, 100ml yeast, 300 ml water? Should boiled tap water be OK or would boiled distilled or spring water be better?

 

[FrozenOcean]

So, I just joined the club. Washed some yeast from a recent batch, and more-or-less (no autoclave!) followed the instructions on the first page of this thread. I now have three 45mL vials of delicious yeast freezing in a tub of isopropyl alcohol. That's worth about $40 up here in Canada!

I'm a low frequency brewer, so it will be many months before I crack one open and see how it worked. But I'm already looking forward to it!

 

[fakeuser]

Great thread. Thanks for the experiments and reading, definitely going to be using this.

Any idea if adding trehalose would help the viability, and if it does do you think you'll be able to shorten the fridge step due to this.

 

[BBL_Brewer]

Just a quick update. I still have some frozen jars of pacman in the freezer from 2012 and they come back to life just fine every year. I only have a couple left, so I'll be plating some out this summer and making a fresh batch. I haven't noticed any differences from year to year in lag time or performance. I've only been thawing out one jar per year of each strain I want to use and then re-pitch for the rest of the brewing season. It's been making my frozen stock last a lot longer since I used to thaw a jar for every batch.

 

[perogi]

Hey all - great thread. Trying to determine if I should buy a "real" pressure cooker or if one of those electric ones will do the job. I've been reading that the electric pressure cookers are not safe for canning. Thanks!

 

[IslandLizard]

Hey all - great thread. Trying to determine if I should buy a "real" pressure cooker or if one of those electric ones will do the job. I've been reading that the electric pressure cookers are not safe for canning. Thanks!

From what I understand you'd need a pressure canner, one that goes to 240F (10 psi) or 250F (15 psi). Pressure cookers don't go that high.

 

[perogi]

From what I understand you'd need a pressure canner, one that goes to 240F (10 psi) or 250F (15 psi). Pressure cookers don't go that high.

Ahh - gotcha. That makes sense. Thank you.

 

[Bigdaddyale]

From what I understand you'd need a pressure canner, one that goes to 240F (10 psi) or 250F (15 psi). Pressure cookers don't go that high.

That's for sterilizing equipment for open heart surgery. I bet an instant pot would work for yeast slants. Sounds like a Brülosophy podcast.

 

[ESBrewer]

The temperature/pressure (combined with time) is the key to get the best results. I'm sterilizing plates and wort with an affordable stove top cooker and in the manual it says it is able to reach 80kPa (11.6 psi) at the highest setting. It seems to work pretty well (I go for 25+ mins). I haven't noticed anything growing on the plates at room temperature yet (except sometimes mold gets into the plate through the microscopic gap between the lid and the dish if left upside down & uncovered). But the higher the pressure the more 100% safe you will be. And I wouldn't buy a cooker that operates lower than 10 psi. If you propagate yeast at home on cheap plates, I would suggest that you wrap plates in alu foil or something so it is going to work great during cultivation. For long term storage, you could wrap them more carefully using parafilm or more sanitized foil. One important thing is to avoid condensed water when handling the plates. I suggest that you sterilize the glassware first, let the hot glass dry (don't open the plates completely to dry them, you can leave a tiny gap for a while or flame them from the inside if they remain wet) then sterilize the wort agar in an erlenmayer or bottle, let it cool down to something like 60°C before pouring the plates. After pouring, you can leave a tiny gap for a while between the lid and the plate so the hot air can escape. Otherwise they tend to be very wet and it will be difficult to work with them, especially because you can't really open them up completely and let dry without getting contaminations at typical homebrewing conditions. Also, if you bring a cold plate to hot and humid air it tends to get wet and the water may provide a bridge for microbes to enter the dish. It is a good idea to prepare slants and plates in forehand so you will be able to see the possible contaminants growing before you plate the yeast.

 

[perogi]

Question about putting the vials in the fridge and then freezing them. How do you keep the glycerin in suspension to protect the yeast? They separate after a few hours. Or is that unnecessary? Thanks!

 

[phishie]

Zombie thread alert!

Has anyone come up with a cheap way to perform the step of freezing the vials in a bath of isopropyl alcohol? Trying to avoid having to track down and buy the correctly sized rack and container to fit my 50 mL tubes.