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

Any viable yeast is usually filtered out or pasteurized unless you know the beer is bottle conditioned. If it's just filtered, you could possible get a culture, but there's not going to be a lot of cells there to work with.

Most of my yeast are from beers I like and when I buy a vial of White Labs, I grow some up and freeze it as well. Most smaller microbreweries here on the west coast at least bottle condition their beer.

Hi everybody!

It's been a while since the last time I wrote on this thread. I'm continuosly using freezing techniques learned here, and I'd like to report some considerations I made.

FREEZING PART OF LIQUID YEAST
Every time i buy a new wyeast pack I collect a part of the yeast the same day that i prepare my starter. usually I take a couple of vials with 18 ml each filled with the content of the yeast pack + 1,5ml of Glycerine. this allow you to use that kind of yeast at least 2 times. I don't want to continuosly reuse the same yeast because I don't think i can perform yeast washing in a proper way (and also because i want to be able to count the yeast cells (in a theoretical way of course). If 125ml of yeast pack has 100billions of yeast cells, each vials should have 12 billions of yeast (80% after freezing). with a couple of starters (0,5l + 1,5l with stir plate) I should end up with about 200billions of cells.

FREEZING DRY YEAST
Tried this few time with Fermentis S-23 and it work great! I only have to re hydrate yeast and fill vials with glycerine ( I use pressure cooker to sanitize everything). the only thing that I have to report is that for some reasons that I cannot explain this vials tend to produce some gas when they are opened ( I don't know why because it is just yeast and water + glycerine). So when I thaw it I have to let the gas out from the vials before putting them in the fridge. I use the fast thaw technic and then let the vials at 4°C to let the yeast settle at the bottom and remove as much liquid as I can.


Also tried to freezing yeast collected with top cropping, I've made a starter but then I decided to not using that yeast. the smell wasn't very good, beacouse I have also collected a lot of hops and proteins. I don't know if you are familar with the smell of krausen (try to skim it once ).

Thanks to everybody for the grat inforomations, this really improved my brewing process, and now that I also have a dedicated fermentation chamber I can brew every kind of beer wherever I want to!:rockin:

SamBrewer said:

If 125ml of yeast pack has 100billions of yeast cells, each vials should have 12 billions of yeast (80% after freezing).

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Where did you get this percentage?
At what temperature you freeze?

SamBrewer said:

I cannot explain this vials tend to produce some gas when they are opened ( I don't know why because it is just yeast and water + glycerine). .

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Probably from CO2 that was trapped in the slurry, when you thaw vials it fills the head space and release after opening.

diS said:

Where did you get this percentage?
At what temperature you freeze?


Probably from CO2 that was trapped in the slurry, when you thaw vials it fills the head space and release after opening.

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The temperature is -20°C, for the percentage I trust what is written in Brewitt's article:

"Glycerin is a cryoprotectant. It helps maintain the viability of frozen cells. We have tested final concentrations from 7.5% to 50% and found 7.5%-15% to be optimal for maintaining viability (upwards of 75% viability after several months of freezing). Lower final concentrations may also work but higher concentrations are detrimental."

of course this is just a theretical calculation but is what I use to have a "starting point" to be able to calculate starters volumes

I found these tubes which look like the ones WL uses to supply their yeast. Would they withstand the pressure cooker sterilization process? I think so, but someone with more experience might have a different answer.

ModlrMike said:

I found these tubes which look like the ones WL uses to supply their yeast. Would they withstand the pressure cooker sterilization process? I think so, but someone with more experience might have a different answer.

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If you read the description closely, it very clearly states that the plastic starts to soften at around 70-80C. These are also sold w/o caps, so you'll have to buy those as well. A pressure cooker routinely gets up to 110-120C and at 10-20 psi, you may see these tubes deform and collapse under the combination of heat and pressure. Just yesterday, I tried to pour some boiling water into a PET plastic container and it melted like the wicked witch of the west. Mind you that was at 100C and 0 psi. My answer is look elsewhere. Try to get something with polycarbonate plastic or borosilicate glass. Read a few posts up from this and you'll see you don't need to freeze 50ml samples because you're still going to have to step it up twice anyways. Go with 10-25ml test tubes and you'll be happy.

fc36 said:

If you read the description closely, it very clearly states that the plastic starts to soften at around 70-80C. These are also sold w/o caps, so you'll have to buy those as well. A pressure cooker routinely gets up to 110-120C and at 10-20 psi, you may see these tubes deform and collapse under the combination of heat and pressure. Just yesterday, I tried to pour some boiling water into a PET plastic container and it melted like the wicked witch of the west. Mind you that was at 100C and 0 psi. My answer is look elsewhere. Try to get something with polycarbonate plastic or borosilicate glass. Read a few posts up from this and you'll see you don't need to freeze 50ml samples because you're still going to have to step it up twice anyways. Go with 10-25ml test tubes and you'll be happy.

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I heated some water in a soda bottle once to test a microwave and that was all I could find. It actually shrank pretty uniformly so we ended up with a much smaller bottle than we started with.

That's why I use canning jars.

I consider this as a good process and there are many yeast fermentation are required. First, fungi or bacteria must be present. Second, no oxygen must be present. Third, an organic compound must be present.

phineascoates said:

I consider this as a good process and there are many yeast fermentation are required. First, fungi or bacteria must be present. Second, no oxygen must be present. Third, an organic compound must be present.

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Have I had too many homebrews or does this not make any sense at all to anyone else either?

LovesIPA said:

Have I had too many homebrews or does this not make any sense at all to anyone else either?

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Engrish at its best.

I was given a box of pyrex 9800 18x150 rimmed tubes. Im thinking about using them to store cultures of yeast in. Will these work ok? And where can I get stoppers for them? My internet search didnt turn up anything.

+edit. It looks like size 2 stoppers. Are rubber stoppers ok to use for this application?

JFK said:

I was given a box of pyrex 9800 18x150 rimmed tubes. Im thinking about using them to store cultures of yeast in. Will these work ok? And where can I get stoppers for them? My internet search didnt turn up anything.

+edit. It looks like size 2 stoppers. Are rubber stoppers ok to use for this application?

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They'll work, but be aware that when you're rousing the yeast from it slumber or any other times of activity, the CO2 the yeast will make may blow a few of your stoppers off from time to time.

Amazon had some of those although I think they were a bit shorter for $7/72. Was going to buy the silicone caps for mine though. Still can be blown off but should have a little bit more forgiving pressure release.

Also for the baby soda bottle link, they come with the caps but still hard to safely sterilize.

Thanks everyone who contributed here. I just bottled up my first attempt at creating my own yeast farm. I went to 6 places and finally found a bottle of Now 100% pure food grade vegetable glycerin. I made a 30% mixture of glycerin to sterile water, then mixed the solution with my yeast slurry left from a starter I made to pitch four 1 gallon batches @ a 1:1 ration which if my math is correct gives me a final concentration of 15%ish due to the unknown content of water in the slurry which I poured as much of the water off of it after cold crashing it overnight. It is now mixed and in my fridge to let it get nice and cold before I put it in the deep freezer tonight. How do I tell if my deep freezer has a thaw cycle? and I am assuming deep freezers are -20 degrees. I only got 1 culture because I had to pitch four batches but it is a good trial run before I go crazy with it

JFK said:

Thanks everyone who contributed here. I just bottled up my first attempt at creating my own yeast farm. I went to 6 places and finally found a bottle of Now 100% pure food grade vegetable glycerin. I made a 30% mixture of glycerin to sterile water, then mixed the solution with my yeast slurry left from a starter I made to pitch four 1 gallon batches @ a 1:1 ration which if my math is correct gives me a final concentration of 15%ish due to the unknown content of water in the slurry which I poured as much of the water off of it after cold crashing it overnight. It is now mixed and in my fridge to let it get nice and cold before I put it in the deep freezer tonight. How do I tell if my deep freezer has a thaw cycle? and I am assuming deep freezers are -20 degrees. I only got 1 culture because I had to pitch four batches but it is a good trial run before I go crazy with it

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Self defrosting freezers will have a thaw cycle. As long as it's not self defrosting, you're good to go. Good luck on your fist attempt.

JFK said:

How do I tell if my deep freezer has a thaw cycle?

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Either you have to defrost it, or not.[/QUOTE]

JFK said:

and I am assuming deep freezers are -20 degrees.

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Zero F for home units.

The freezer above my fridge hovers around -17 degrees F and spikes up to around 0 at periodic intervals (the frost free side of it I assume). My deep freeze only runs at -6 F but sustains it very well. That's only when it's near full. The fridge unit is rarely more than 1/4 full but the top shelf of my fridge will also freeze items solid as well. I made the mistake of storing yeast there once... Only once.

Accidic said:

The freezer above my fridge hovers around -17 degrees F and spikes up to around 0 at periodic intervals (the frost free side of it I assume). My deep freeze only runs at -6 F but sustains it very well. That's only when it's near full. The fridge unit is rarely more than 1/4 full but the top shelf of my fridge will also freeze items solid as well. I made the mistake of storing yeast there once... Only once.

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Use your deep freeze for storing frozen yeast, that will give you the longest shelf life. If you absolutely have to use the freezer above your frige, then store the yeast in a small cooler with some ice packs if possible.

Accidic said:

The freezer above my fridge hovers around -17 degrees F and spikes up to around 0 at periodic intervals (the frost free side of it I assume). My deep freeze only runs at -6 F but sustains it very well. That's only when it's near full. The fridge unit is rarely more than 1/4 full but the top shelf of my fridge will also freeze items solid as well. I made the mistake of storing yeast there once... Only once.

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I was in appliance repair over 30 years. -17F is pretty cold for a top mount freezer. Zero has been the recommended and industry standard for a long time. I recently 'worked' on one for a friend who said his freezer just wouldn't stay cold enough. The problem? His thermometer. Freezer was fine. At -17F I kinda doubt your thermometer to be honest. Possible but unlikely you maintain that temp depending on the age of the unit. The newer the unit the less likely that it has that much over capacity.

The thermometer flickers between 1 and 0 in a bowl of ice water so it's probably a tiny bit off but it seems solid otherwise.

I used to use the deep freeze but it is opened a heck of a lot more and can be 1-2 degrees above 0 for more than an hour. IE, it's old. The only thing the top freezer is used for is storage of certain food items so I use it for the only 3 samples I keep. I keep them sealed in a thermos I drilled, filled 90ish percent full of chillpack gel, and replugged. This seems consistent with the manu's claims that it freezes between 8-10 degrees below. The cooler would probably work too but I got the thermos free and it fits perfectly in the bottom corner of that freeze plus is airtight and I'm not truly convinced the lids on my vials actually are. Also, as a sidenote, I can turn the dial on my fridge down to get closer to zero (lowest is actually -1 on my thermo) and it freezes ice at that temp without issue. But I make my own Ice Cream and I like it to stay nice and hard (much to my wife's chagrin).

I do not have time to read all the posts on this thread at the moment so excuse me if this has been previously addressed.
I would like to give this a shot and have a bottle of Faulding (Remedies) Glycerine which seems to be 100%Glycerol.
It is described as an application for roughened skin. Faulding customer support told me that they do not recommend its use in cooking (making icing etc) as it can cause dehydration if ingested in other than very small amounts?

Would it be ok to use this for freezing yeast? Had a look in the supermarket but glycerine seems harder to find than rocking horse manure.

Accidic said:

I keep them sealed in a thermos I drilled, filled 90ish percent full of chillpack gel, and replugged.

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I like the gel idea. So it's just a container filled with gel and holes for the vials to slip into?

el_caro said:

I do not have time to read all the posts on this thread at the moment so excuse me if this has been previously addressed.
I would like to give this a shot and have a bottle of Faulding (Remedies) Glycerine which seems to be 100%Glycerol.
It is described as an application for roughened skin. Faulding customer support told me that they do not recommend its use in cooking (making icing etc) as it can cause dehydration if ingested in other than very small amounts?

Would it be ok to use this for freezing yeast? Had a look in the supermarket but glycerine seems harder to find than rocking horse manure.

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You want to use food grade vegetable glycerine. If they tell you it's food grade then go ahead and use it, but if it's not, then I would find something else. You can order it off the net. That's what I do. I just get a gallon at a time and it lasts forever. A good brand is "Now" It's made here in the United States. Be careful about ordering glycerine made in China.

Thanks BBL - Will take your advice and look on the net.

Another stupid question but there are so many figures floating around on this thread that my head is spinning.

Is the general consensus that if I wish to make a pint (473ml) of glycerine solution to add to the yeast - then the glycerine solution should be made with 131 ml glycerine to 342ml of water and then the ratio of yeast slurry to glycerine solution should be 50:50 ?

el_caro said:

Another stupid question but there are so many figures floating around on this thread that my head is spinning.

Is the general consensus that if I wish to make a pint (473ml) of glycerine solution to add to the yeast - then the glycerine solution should be made with 131 ml glycerine to 342ml of water and then the ratio of yeast slurry to glycerine solution should be 50:50 ?

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I've had the best luck with a final concentration of ~18-20% v/v. In other words I mix 131 ml of glycerine with 342 ml of water and then mix that solution between 70:30 and 65:35 with my yeast slurry. 65-70% glycerine solution and 30-35% slurry. There still seem to be varying opinions on this, so you might want to experiment a little, but the general consensus is that you shouldn't need any more than that.

BBL_Brewer said:

I like the gel idea. So it's just a container filled with gel and holes for the vials to slip into?

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No, it's actually a thermos with the outer layer drilled to allow the gel to fill it and I insert the vials into the container. I had some rubber plugs from god knows what laying around that filled the hole perfectly without problem. The lid to the thermos is an airtight screw on lid. I glue small disc magnets onto the tops which makes retrieving them very easy with a telescoping magnet.

Admittedly the gel (I used Easychill IIRC) reduces the effectiveness of the thermos effect slightly but it does have a few other benefits. For one, the gel has to melt before it drops below 0. Even if it's not frozen completely, it's still frequently colder than 0 degrees (limited to the freezer's lowest temperature of course) and this cools the inner chamber of the thermos reducing the ways for heat to get into the vessel as it hypercools the metal connection to the inner chamber at the lid level (if that makes sense). And finally most importantly, the metal cylinder ensures that if one of the vials were to explode or get broken, the glass would be safely segregated from the rest of the freezer meaning the wife is much more complacent about one of my many "projects." Admittedly I cannot provide evidence that this works any better than using a small cooler but I would think it more efficient and if nothing else it takes up far less space in our freezer. The thermos I have is a promo item I got for free and I can actually comfortably fit 9 of my current vials in it with a small amount of headspace at the top. I guess I could look into filling the container with glycerine which in it's raw form would not freeze (at least in my freezer) barring heavy dilution but it just seems like overkill.

Sidenote, out of curiousity regarding the comments about temp yesterday... I'm testing the temp in my freezer presently by freezing glycerine & water mixtures. 25/75 froze fine in the freezer but not the chest freeze. I mixed up a 40/60 mix and replaced the frozen one this morning. I figure if that one turns the thermometer is at least marginally accurate since the freezing point should be ~16 degrees below or my scale is off...

Accidic said:

No, it's actually a thermos with the outer layer drilled to allow the gel to fill it and I insert the vials into the container. I had some rubber plugs from god knows what laying around that filled the hole perfectly without problem. The lid to the thermos is an airtight screw on lid. I glue small disc magnets onto the tops which makes retrieving them very easy with a telescoping magnet.

Admittedly the gel (I used Easychill IIRC) reduces the effectiveness of the thermos effect slightly but it does have a few other benefits. For one, the gel has to melt before it drops below 0. Even if it's not frozen completely, it's still frequently colder than 0 degrees (limited to the freezer's lowest temperature of course) and this cools the inner chamber of the thermos reducing the ways for heat to get into the vessel as it hypercools the metal connection to the inner chamber at the lid level (if that makes sense). And finally most importantly, the metal cylinder ensures that if one of the vials were to explode or get broken, the glass would be safely segregated from the rest of the freezer meaning the wife is much more complacent about one of my many "projects." Admittedly I cannot provide evidence that this works any better than using a small cooler but I would think it more efficient and if nothing else it takes up far less space in our freezer. The thermos I have is a promo item I got for free and I can actually comfortably fit 9 of my current vials in it with a small amount of headspace at the top. I guess I could look into filling the container with glycerine which in it's raw form would not freeze (at least in my freezer) barring heavy dilution but it just seems like overkill.

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Oh, ok. I guess I misunderstood.

If you were more crafty you could sand cast a mold fit to the vials, spray it with plastic and fill it with gel alternatively and just seal it with insulated lid. I'm not nearly that crafty though. The price on the thermos was right (free), I had the gel extra from shipments of yeast just sitting around, and I had the plugs and magnets sitting around collecting dust so it kind of just came together since I needed something smaller than a small cooler to keep the peace in my house.

BBL_Brewer said:

I've had the best luck with a final concentration of ~18-20% v/v. In other words I mix 131 ml of glycerine with 342 ml of water and then mix that solution between 70:30 and 65:35 with my yeast slurry. 65-70% glycerine solution and 30-35% slurry. There still seem to be varying opinions on this, so you might want to experiment a little, but the general consensus is that you shouldn't need any more than that.

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Thanks again BBL for the quick response and thanks to all who have made this a really great thread that I think should be considered for a sticky.

Someone in my brew club brought up a concern that I did not have an answer for. He said and I'm quoteing not stateing according to whites book there is mutation that occurs at -20 storage that does not occur at -80. Is this true and if so how will it effect my brew.

JFK said:

Someone in my brew club brought up a concern that I did not have an answer for. He said and I'm quoteing not stateing according to whites book there is mutation that occurs at -20 storage that does not occur at -80. Is this true and if so how will it effect my brew.

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You'll be making "Mutenbrau"...

It is true that yeast are more stable at -80C but there is no specific mutation that occurs at either temperature that I am aware of. In fact, mutations occur more slowly in the cold and especially below freezing. The reason for the additional stability is that the colder conditions are both better for preserving cellular structure and preventing chemical change. My recommendation would be, don't worry about it.

I need to thaw out one of the tubes I put up and see what I get. I already know I'll need to make a couple/few starters to get the cell count needed. Just need to have the free time to brew. Believe it or not, even when between jobs, you don't have as much 'free time' as you would think.

Seems like you'd have less time between jobs due to being forced to look for the next job.

BBL_Brewer said:

It doesn't have to be this difficult. What I reccomend is that you put all of your yeast slurry into a large container with volume markings. Add your glycerine solution and any top of water if needed, then split it up into whatever you're going to freeze in. Unless you're using a centrifuge, there's no reason not to. I have marks on my starter vessels so I just do it in there. I know what I want my final vomue to be (500 ml) so I use the following equation: Final Volume x Desired Glycerine Concentration (%) / Concentration of Glycerine Solution

So for example Let's say 500 ml final volume, 15 % v/v final concentration, 60% glycerine solution. (500 x 0.15) / 0.6 = 125 ml of 60% glycerine solution required.

Add your 125 ml, top off with sanitized water.

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I am still frustrated with this formula. I don't know what my final volume is going to be, how does anyone know that?. I need the formula for figuring out how much glycerine solution is require for a specified amount of yeast slurry. What is that?

Is this correct?

Yeast Slurry Volume / 0.30= Total Volume
Total Volume * 0.7= Glycerine Solution Volume
Glycerine Solution Volume *0.6= Glycerine Volume