Let's Freeze Some Yeast

[tateg]

That's not great for them but won't kill them outright.

All the same or different?

[SIZE=11pt]Three different strains, mostly house strains. They had only been in the freezer for 3 weeks.[/SIZE]
[SIZE=11pt]So you think it may be worth refreezing them ?[/SIZE]
[SIZE=11pt]i guess i may aswell then test one after a week or so [/SIZE]

 

[Yob]

Personally, I'd chuck them in small starters, just a little jar or something, then Re freeze once they've settled out

one of each that is, that way ypu have a viable fallback if they start to fail

 

[Danwood]

I stepped up, split into 5, and froze a pack of Bry97 (50% viability), just to try my hand.

Using Wolfy's method, and quickly thawed after a short spell in cryo-sleep (2 weeks), it's kicked on like a good 'un in a Citra pale.

Stepping up a whole pack in a 2L starter, then splitting 5 ways is going to result in a decent sample per vial (anyone want to run that through Mr Malty? I had it on android but not on this shitbag Apple phone).

The vial then went through 200ml, 500ml and 2L starters.

Anyway, exciting times indeed.

Thanks for all the helpful posts.

 

[menoetes]

I'm currently stepping up a Wyeast Kolsch yeast I tried freezing 3 months ago... I say 'tried' because it didn't freeze. Maybe my glycerin/water ratios were off but it went into a freezer surrounded by ice but remained in liquid form for the whole time it was in there, has anyone else had an experience like this?

Anyway I through it into a small starter on the stirplate on Wednesday and after 24 hours there was no activity so I lost heart and turned it off. However this morning when I got up, almost 48 hours after pitching it, there's a sign of life in my starter after-all! So I turn the stirplate back on and it forms a krausen almost immediately.

My only concern is the slow start-up and I'm worrying it might be an infection rather than the yeast. Again; has anyone else had an experience like this? I'm just looking for a second opinion before I throw this uncertainty into 21lts of Kolsch wort...

 

[Mardoo]

The not freezing would be high glycerin/water ratio. I often have frozen yeast show little to no movement in my first step with 1.020 wort, which I learned from Yob. The next step everything kicks off as normal.

I do 3 steps: 150ml at 1.020; 500ml at 1.040; and 2 or 3 litres at 1.040.

Taste the starter wort and that should give you an idea regarding infection. I always taste my starter wort.

 

[mofox1]

Been going yeast freeze crazy over the past couple of weeks.

Just starters to build up stocks of older / limited stock, but I've done:

7 x 15ml vials of WLP023 Burton Ale - 5th gen, same "house" strain that has so far reached 83% AA with the ~1.100 bummock wort.
10 x 15ml vials of MJ Bavarian Wheat - pack was 1 yr past bb - still went nuts. Pack was pitched into a 3L starter, the 10 vials were from 2/3 of the resultant yeast. Other 1/3 built back up to pitch into a wheat.
? x 15ml vials of WLP041 Pacific Ale - last step for this one running now... probably didn't need it. Will easily get 10+ vials with probably enough left over to pitch straight into a PA.

Got stocks of Cal Ale, London Ale & Sth German Lager to build up next. If I'm not sick of it, I've got some older 007, 009 & coopers to revive too.

Safe to say I'm using up a wee bit of DME right now. Fun times.

 

[lael]

ok, so what is the current recommended method for this?

freezing: 50ml vial - 50% glycerine, 50% decanted yeast slurry (crash cooled, clear wort discarded, slurry packaged). Place in fridge for 2 days before placing in freezer

re-activating: place in room temp glass of water for 5 mins, change water. Sit to bring to room temp OR: hold in hand until hits room temp. Pitch into 200ml @ 1.020, repitch to 500ml@ 1.040, repitch to 2L @ 1.040.

Questions:
freezing: some mention that 50/50 doesn't freeze and won't show action in the first step. That shouldn't be a problem as long as they are kept at freezing temps right? Might it be better if the cell walls don't freeze solid?
If not - increasing the ratio of yeast slurry to 60/40 or 70/30 should do the job?

re-activating: Are you guys cold crashing between steps or just adding the 200ml to the 500ml of fresh wort etc?

Did the Melbourne bulk buy of glycerine happen a while back?

I've contacted some suppliers in Sydney and generally they are cosmetics companies. They buy the glycerine in 250Kg packages (that are food grade / organic / BP) and re-pack it, but their facilities/ procedures don't meet/ aren't certified to food grade standards and therefore they can't sell it as such. One supplier I'm thinking of buying from uses a clean room, packs one product at a time, personnell use disposable protective gear (gloves, hair nets etc) use disposable equipment for repacking or wash it between uses with soap and warm water. Thoughts?

 

[Mardoo]

You should absolutely be autoclaving/pressure cooking vials with your glycerine/water yeast medium so if the glycerine is not hermetically packed it shouldn't be such an issue. I haven't had issues yet.

 

[Yob]

so 2 days ago, I took out a vial of 1728 from the deep freezer, this vial has been rock solid for a year or so..

had about 10ml yeast solids in it, I put that into a 500ml 1.020 starter overnight, the next morning, there was visible signs of activity, condensation on the inside of the flask, a lightening of the wort.. so that evening, I made 2 x 2lt starters of 1.040 and split the 500ml between them.. again, overnight they were showing signs of activity, at 18hrs to 24hrs they were starting to foam so Ive turned them off and will let them ferment out before pitching to the Bummock Ale (~1.100 Scotch Ale / Heavy Wee Heavy)

Stoked and pretty impressed at the revival

 

[Yob]

ok, so what is the current recommended method for this?

freezing: 50ml vial - 50% glycerine, 50% decanted yeast slurry (crash cooled, clear wort discarded, slurry packaged). Place in fridge for 2 days before placing in freezer

I make up a %50 solution and add my yeast to that so I end up with a ~%25 solution final with solids

re-activating: place in room temp glass of water for 5 mins, change water. (Yes) Sit to bring to room temp OR: hold in hand until hits room temp. Pitch into 200ml @ 1.020, repitch to 500ml@ 1.040, repitch to 2L @ 1.040. (I ALWAYS start with a 500ml @ 1.020)

Questions:
freezing: some mention that 50/50 doesn't freeze and won't show action in the first step. That shouldn't be a problem as long as they are kept at freezing temps right? Might it be better if the cell walls don't freeze solid? (anecdotally no, I prefer a less than %50 solution)
If not - increasing the ratio of yeast slurry to 60/40 or 70/30 should do the job? (as above, I make up a 50/50 solution of glycerine and sterile water and add that to my vials with 25ml yeast solids/wort)

re-activating: Are you guys cold crashing between steps or just adding the 200ml to the 500ml of fresh wort etc? (I'll make up the next step to include the volume.. so, if I have a 500ml starter, Ill make up a 200g/1.5lt starter and add the 500ml to make the full 2000ml if that makes sense?)

Did the Melbourne bulk buy of glycerine happen a while back? (Yes, Mardoo is the man for those details)

I've contacted some suppliers in Sydney and generally they are cosmetics companies. They buy the glycerine in 250Kg packages (that are food grade / organic / BP) and re-pack it, but their facilities/ procedures don't meet/ aren't certified to food grade standards and therefore they can't sell it as such. One supplier I'm thinking of buying from uses a clean room, packs one product at a time, personnell use disposable protective gear (gloves, hair nets etc) use disposable equipment for repacking or wash it between uses with soap and warm water. Thoughts? (I do sometimes, if I can be arsed, microwave/autoclave some vials in advance, sometimes my practice is a little less than perfect... Ive not yet sneezed into a vial though)

 

[lael]

How far in advance have you guys pressure cooked the glycerin? Is that - mix water and glycerine and fill vials to half way and then turn the pressure cooker on? For how long? How much water do you put in the bottom of the pressure cooker?

 

[Mardoo]

You can do the glycerine/water vials in advance and keep them in the fridge for a couple weeks. Remember to bring them back to room temp if you're pouring room temp yeast in.

 

[MartinOC]

How far in advance have you guys pressure cooked the glycerin? Is that - mix water and glycerine and fill vials to half way and then turn the pressure cooker on? For how long? How much water do you put in the bottom of the pressure cooker?

Each cooker will be slightly different, so it depends on the model you have. If you can put your vials into a cage or perforated pot to keep them off the bottom, all well & good. Leave the lids on the vials, but loosen them off.

You only need enough water to create the steam under pressure (that's about 120-ish degrees C), so 1cm or so will be heaps. Bring it up to pressure, leave it for 10-15 minutes, then turn the heat off & let it cool down naturally. Overnight is fine.

Once cool, you can open the cooker & screw-down the lids on the vials. They can then be refrigerated or frozen as-is for when you want to transfer & store your yeast (obviously, both the vials & yeast should be at the same temperature when you do this!). Then freeze them.

As an anecdote, I created slants in screw-top McCartney bottles in much this same way & promptly forgot about them for about 10 years :blink:. Not refrigerated the whole time. When I found them again, not a single one was contaminated.

 

[Bridgey23]

Man I wanna freeze yeast and have everything except a pressure cooker. Do I need to pressure cook? Or can I just clean and sanitise?

 

[Yob]

You can use water that's been boiled 3 times over 3 days... Considered sterile at that point..

It's a bit if overkill to be honest, I used just boiled water for rinsing for ages, never noticed any issues, know the risks and be comfortable with the level of risk you choose.

We do tend to err on the side extreme caution most times..

 

[MartinOC]

Man I wanna freeze yeast and have everything except a pressure cooker. Do I need to pressure cook? Or can I just clean and sanitise?

Cleaning & sanitising is fine & you'll still get good results. Using a pressure cooker is going that extra step to ensure you get the best results possible every time.

Edit: And it's for yeast-freezing geeks.... h34r:

 

[Bridgey23]

Cheers Yob. I'm new to this. All this! Brewed can goop and sugar about 20 yrs ago. Drinkable but never followed through. Have been inspired lately. Love real beer and jumped straight into all grain and lovin it. Only 5 brews in but remarkably better beer.
I'm a tight arse like most home brewers and have started splitting liquid yeast starters but see this as an even better solution to yeast costs and of course having particular strains on hand.
Cheers again Yob you are wealth of information. For us newbies.

Edit: cheers Martin I'm getting geekish. The advice on this forum is fantastic and very much appreciated. I've never found a hobby that has grabbed me like this. Bloody expensive but extremely satisfying.

 

[Bridgey23]

And Yob. If your doing the boil over three days for rinse water method do you wack a lid on it between boils? Put it in the fridge? What's the process?

 

[mofox1]

I'm a tight arse like most home brewers...

...I've never found a hobby that has grabbed me like this. Bloody expensive but extremely satisfying.

LOL. This.

Pretty much sums up what happens when you slip down that slope..

 

[Yob]

And Yob. If your doing the boil over three days for rinse water method do you wack a lid on it between boils? Put it in the fridge? What's the process?

Gladwrap if you can be arsed.. I gave up on it pretty quickly