Yeast Question

[BeerMan]

I just finished culturing my 1st yeast slants, I thought I had this all figured out but like with any new endeavor in brewing a question pops up. I have read a slant will survive up to a year refrigerated so here is my question. Refrigerated or frozen, I know that the labs use liquid nitrogen to store yeast but I believe I read somewhere once that freezing in a standard freezer will cause cell wall damage to the yeast because it doesn’t get cold enough fast enough. Any Ideas or experience in this area would be appreciated.

[bub]

the real problem with freezing is the freeze thaw cycle of a standard freezer. There was a session where this was discussed (note 8-12-07)
Check it biotch.
BUB

[BeerMan]

will take a listen thanks bub

[Sent From My iPhone]

When we freeze bacteria in my lab we add glycerol to the freeze media. We freeze them to -80. Human and rodent cells get DMSO added and they're frozen in liquid nitrogen. Not sure what you need to do to freeze yeast, but if it's not done quickly and correctly you'll get few viable cells when thawed.

[DaaB]

the real problem with freezing is the freeze thaw cycle of a standard freezer. There was a session where this was discussed (note 8-12-07)
Check it biotch.
BUB

Isn't that only a problem with frost free freezers?

Adding 50/50 slurry, 70/30 glycerinesolution protects the cell wall from rupturing while freezing.

[BeerMan]

I was thinking about using the gel ice packs or make an ice block and drill it to accept the slants to maintain a constant temp. but the other question is how long will a slant last in the fridge vs the freezer

[Ragde!]

here is a thread I started before on the subject.

http://thebrewingnetwork.com/forum/vie ... highlight=

I have sev vials in the freezer. I am waiting to try to bring them "back to life" and then I will send out some of the beer I make with it to get some feed back. If anyone cares its cal. ale yeast.

[DaaB]

I was thinking about using the gel ice packs or make an ice block and drill it to accept the slants to maintain a constant temp. but the other question is how long will a slant last in the fridge vs the freezer

It all depends on the yeast. I have vials of Hop Back yeast (Summer Lightning) that i've kept in the fridge for the last 6 months and it's still good but i've had samples of Hook Norton yeast collected from the brewery that's turned nasty after 1 month. I live quite close to the Ringwood brewery and get their yeast regularly and I tend to ditch that after 3 months.

Slants on the other hand should last longer prepared properly, longer still if frozen. There's a guy in another forum who claims to have used a Brewlabs slant that was 18 months old without any problems and that stored under sterile mineral oil near freezing they should last indefinitely.

FWIW I generally don't bother with slants I just make a 5L starter and split the yeast into 5 or 6 Steraline vials (or small pet bottles) and make a fresh starter with each one before brewing. I leave all the hard work to White Labs, Wyeast and Brew Labs.