Stretching my starter

clayof2day · 03-09-2006, 10:57 PM

Hey Everybody,

I wanted to try an experiment with freezing some yeast. I have everything I need, but I wanted to do enough of a starter to make 4 50 mL aliquots, 2 to brew with and 2 to try to freeze. I made up a starter with about a cup of DME in about 900 mL of water. After I force it to settle in the fridge do you think that this will be enough yeast to stretch or should I settle it and add some more DME to build up again.

FWIW this was the most active starter I've made so far. I pitched the vial of White Labs Cali Ale yeast and it fermented up into the arilock on my flask and took about 4 days to ferment out!!

Brewsmith · 03-09-2006, 11:16 PM

I don't think freezing the yeast is such a good idea. Yeast is alive. Freezing would probably kill them. Just keep them refrigerated.

clayof2day · 03-09-2006, 11:27 PM

There are some special procedures you have to follow. If you include gylcerine or DMSO (which is probably not a good idea, seems as we plan on drinking this later) it will keep the cell walls from fracturing when they freeze. They principle is the same for freezing cells that grow in petri dishes. It can be done, but you will lose some in the process, need a big starter when you're done I'm assuming.

This is the page that got me interested.

Brewsmith · 03-10-2006, 01:08 AM

Ok, it can be done. I still don't think I would want to go through with it. I have re-used yeast from starters, just bottling it and putting it in the fridge. When I need it, I take it out and make another starter. The freezing process just seems like alot of work for nothing. I buy yeast from the LHBS and they have it refrigerated. Seems good enough for me. Just my $0.02.

Lou · 03-10-2006, 01:18 AM

you should be able to freeze them and revitalize them without an issue if you use glycerol. but you'd want them in a deep freeze (-80C or even liquid N2 temps) if you want them to last a long time... i'd recommend using a smaller aliquot than 50mL, also, so they freeze quickly and thaw quickly.
that being said, i can't think of any good reason to freeze these as opposed to just storing them in the fridge in a bottle or even one of those test tubes...

Lou · 03-10-2006, 01:22 AM

oh, also....if you have a frost-free freezer, it will cycle and freeze-thaw your yeast repeatedly....so your yeast will die in the freezer... unless you put it in something insulated in the freezer.

**Walker** · 03-10-2006, 01:47 AM

??? aren't most freezers (attached to fridges) frost-free freezers? if so, I'm not sure I agree with that last statement, Lou.

-walker

Lou · 03-10-2006, 03:33 AM

Quote:

Originally Posted by Walker

??? aren't most freezers (attached to fridges) frost-free freezers? if so, I'm not sure I agree with that last statement, Lou.

-walker

well, i suppose if you're freezing 50ml aliquots it won't be an issue. but if you use a small volume, it'll matter.

El Pistolero · 03-10-2006, 04:07 AM

Jeez people, we're home brewers...if you have to screw with glycerol, DMSO, DMT, or aliquots, then what the heck is the point.

And what/where/why on earth is an aliquot, and why do you need more than one?

Lou · 03-10-2006, 04:56 AM

Quote:

Originally Posted by El Pistolero

Jeez people, we're home brewers...if you have to screw with glycerol, DMSO, DMT, or aliquots, then what the heck is the point.

And what/where/why on earth is an aliquot, and why do you need more than one?

i agree....like i said originally, just put the yeast in the fridge...
and, for EP (and my own sanity), i'll try to refrain from science talk...