Let's Freeze Some Yeast

[Yob]

No..

Cmon Michael Burton aka digital stirplates with the temp controlled unit though...

 

[lael]

I've not read this whole thread but was wondering if anyone has mentioned that growing your cryo-culture in a very nutrient poor medium will greatly increase viability.
the cell walls of well fed yeast have a high tendency to rupture leaving only those colonies that are less than optimum because of pre-existing nutrient uptake issues.


Edit: I should elaborate considerably more. The yeast needs to be cultured @25°C for 72h in YM media.
Grown in 10ml vials.

The YM media recipe is such:

3g yeast extract
3g malt extract
5g peptone
10g glucose
deionised water to make to 1 litre

The cryoprotectant solution should be 10%v/v glycerol mixed equally with the innoculum

What is YM media?

 

[Mardoo]

And can you provide some links so we can learn more about this?

 

[Tex N Oz]

What is YM media?

YM media is a product produced by Beckton Dickinson. It's like calling facial tissues a Kleenex of sorts.

And can you provide some links so we can learn more about this?

Most of it's from papers I've collected over the years. I used to be hardcore into lyophilization.
I could try to scan in some ****.

I've been toying with this for years.

 

[Tex N Oz]

Bad news for everyone though.. without proper lyophilization, none of these innoculums will be viable past 2 years with the temperatures that you're using.
You don't even start to get into cryo-preserving until -80°C.
You might get some petite colonies on your strikes but you don't want those. They're the ****** ones that are just barely hanging on and very hard to start. You'll also notice a HUGE change in profiles as mitochodrial damage is usually the cause.

 

[Tropico]

No ****

 

[Yob]

so not really useful at all.. I keep mine at a pretty steady -20'c and am happy with the results thus far without it being overly complicated...

one of the things that got me into this side of the yeast ranching game over many other methods.

KISS

 

[Bridgey23]

Looks like your ganna have to look into liquid nitrogen storage now Yob. Does it ever end?[emoji6]
Keep us informed if you do!

 

[Bridgey23]

Ha ha how far do you wanna take it?
http://www.boconlineshop.com/shop/en/au-boc-industrial-store/liquid-nitrogen-storage/mve-lab-20-liquid-nitrogen-dewar-mve13492631-p

 

[Tex N Oz]

so not really useful at all.. I keep mine at a pretty steady -20'c and am happy with the results thus far without it being overly complicated...

one of the things that got me into this side of the yeast ranching game over many other methods.

KISS

It's important to understand that raising yeast from a cryo or lypho state isn't as simple as pitching into some wort and off it goes. You must ALWAYS strike your sample first, then grown it on a petri dish and then start a 10ml starter then up from there. There's no easy way to start from a dehydrated sample. Even those samples that are frozen in a freezer are considered dehydrated.
The yeast have many many colonies and you want to start only the healthiest of these and not a mix of these.
If your goal is to bank yeast that will keep for years and years and years at 1°C, then you must involve lyophilisation or true cryo-freezing (liquid nitrogen @ - 160°C max) and then understand that it will take you upwards of 2 weeks to have a viable starter.
I truly hate to come across as a "know it all" and sometimes I come across that way but I have extensively studied this and only sharing my experiences and learning.
There's a reason you don't buy frozen yeast in the freezer section of your LHBS.

 

[Yob]

Practical experience suggests different.

Results are speaking for themselves. Are there damaged colonies? Probably, does it make a noticeable difference? No.

DIGAF? No, the system I utilise works well enough and I'm happy with it and that's the important thing here.. It's a simple, effective, home brew solution to a yeast bank that works.

Perhaps you should start another thread on that method so as not to De rail this one.

 

[Tex N Oz]

Practical experience suggests different.

Results are speaking for themselves. Are there damaged colonies? Probably, does it make a noticeable difference? No.

DIGAF? No, the system I utilise works well enough and I'm happy with it and that's the important thing here.. It's a simple, effective, home brew solution to a yeast bank that works.

Perhaps you should start another thread on that method so as not to De rail this one.

That's fair enough. How long are you able to keep viable samples?

 

[Yob]

Well over 18 months currently... And counting

 

[Tex N Oz]

Well over 18 months currently... And counting

Are you finding that it works better for some strains than others?

 

[Yob]

I'm finding the glycerine content is more critical, I went from %15 to %50 but have found the best results at about %25-30

 

[Tex N Oz]

That's interesting. All of my experience has been with cryo freezing @ 5% total solution.
I might give the higher concentration and higher temperatures a try. There are a lot of times it would be handy to have a larger sample ready to go.
Have you given any of the lager yeasts a go?

 

[Yob]

I've got some frozen but not Re cultured, I tend not to brew a lot of lagers. I'll pull one out this week just for ***** and giggles

 

[Tropico]

According to Chirs White and Jamil Zainasheff, it is possible to have a reliable shelf life up to 2 years and maximum shelf life longer than 5 years when stored between -2 and -19C. At -80C , they quote both as "indefinite".

 

[menoetes]

Just a quick follow up from my post about a week back; the Wyeast Kolsch slurry/glycerine solution that didn't actually freeze in the freezer did kick off in the end (also I'm quite sure it's not an infection like I first feared) and I stepped in up from 100ml to 400ml then 1lt then 2.4lts - nice and easy.

It's found it's way into my Kolsch wort last night and I have high hoped for it. So for future reference - even if your yeast slurry doesn't freezer, hold onto it - it might still make a go of it if treated gently in restarting.

 

[barneey]

Following Yob's method, Green Belt yeast frozen Dec 14, resurrected October 15 so I would call that a success.

Cheers