Refreezing Slants

[reviled]

Long story short, all my slants got thawed and are now back in the freezer - ive been told and read that this stuffs the viability

SO im wondering if anyone else has had any experiance with refreezing slants?? Have you done this then been able to use the yeast down the track? Or should I save myself future pain and throw them all away?

Grim as I only just acquired them all!

 

[Sammus]

Freezing? :blink: I thought freezing them once would ruin them...

 

[t2000kw]

Freezing? :blink: I thought freezing them once would ruin them...

The technique I learned but never really used was to let the yeast settle out in a vial and use a dropper to remove the water above the yeast, then add some glycerol, shake, then freeze.

The glycerol keeps the yeast's cell walls from freezing and killing the yeast.

I don't know how cold you can freeze it, but I think it's good to well below the temperature of frozen water.

You DON'T want to freeze dried yeast, though, even though some home brewers I know get away with it. According to Lallemand yeast company, that kills off most of the yeast. Refrigeration in an unopened packet will keep them viable for years (possibly up to 10 years), with decreasing viablilty over time, of course.

 

[raven19]

Yeah I wouldnt be freezing my yeasts.

My slants are in the fridge and are fine.

A mate had some yeast in bottles in his fridge which then froze up. Went to make a starter with them and no good.

Question is will these be any good? I would add a little cooled (after being boiled) wort at around 1040 into each test tube in a santiary manner. Wait for any sign of action/fermentation. If you have action, you are on a winner, if so then I would recommend creating making 3 new slants of each of your yeasts.

Once grown then store in the fridge.

If no action they may all be ruined?

 

[Sammus]

The technique I learned but never really used was to let the yeast settle out in a vial and use a dropper to remove the water above the yeast, then add some glycerol, shake, then freeze.

The glycerol keeps the yeast's cell walls from freezing and killing the yeast.

I don't know how cold you can freeze it, but I think it's good to well below the temperature of frozen water.

You DON'T want to freeze dried yeast, though, even though some home brewers I know get away with it. According to Lallemand yeast company, that kills off most of the yeast. Refrigeration in an unopened packet will keep them viable for years (possibly up to 10 years), with decreasing viablilty over time, of course.

I thought you need a special deep freezer to store them at about -80 if you were doing the glycerol thing...my memory rarely serves me well though <_< lol

 

[reviled]

I got a mate qwho works in a lab to mix with glycerile and he said it would be sweet in the freezer.. All good..

The problem is, i woke up this morning and my fridge had been turned off :angry: So they thawed... Ive turned the fridge back on, but then got to work and am reading about how thawing then freezing again can effect the vaibility

So has anyone had any slants that have thawed, then been re-frozen, then used? lol

 

[Ronin]

I thought you need a special deep freezer to store them at about -80 if you were doing the glycerol thing...my memory rarely serves me well though <_< lol

Ive got several yeast strains stored at both -80 and -20 in glycerol. You can store them at -20, but the life of the stock is significantly shorter.

 

[RobW]

I'd culture them first. that way you know if they're still viable.
Then store fresh cultures of the ones that grow.

 

[Quintrex]

I'd culture them first. that way you know if they're still viable.
Then store fresh cultures of the ones that grow.

I'm pretty sure they'll be fine. After all the whole purpose of having the glycerol in there is to prevent the damage to the cell from freezing/unfreezing. When you culture from them you thaw at least some of it right?

 

[t2000kw]

I thought you need a special deep freezer to store them at about -80 if you were doing the glycerol thing...my memory rarely serves me well though <_< lol

No, you don't. Good results can be obtained at regular home deep freezer temperatures or in the freezer part of a refrigerator.

http://www.homebrewtalk.com/wiki/index.php/Yeast_bank

 

[Thirsty Boy]

my understanding (could be wrong) is that even under glycerol, you will lose somewhere around 10-20 viability each time you freeze/unfreeze the yeasts - so having them thaw out will knock them around a little but not finish them off.

I had no luck with the glycerol and freezing method - but I strongly suspect that was about a less than reliable fridge than any flaw in the idea.

 

[~MikE]

The problem is, i woke up this morning and my fridge had been turned off :angry: So they thawed... Ive turned the fridge back on, but then got to work and am reading about how thawing then freezing again can effect the vaibility

So has anyone had any slants that have thawed, then been re-frozen, then used? lol

slants, you don't want to freeze. if you've got the cells in 20% glycerol then you might have luck in a conventional freezer, never tried it myself (-80C all the way for me). a freeze/thaw cycle will typically kill ~50% of your viable cells.

 

[reviled]

slants, you don't want to freeze. if you've got the cells in 20% glycerol then you might have luck in a conventional freezer, never tried it myself (-80C all the way for me). a freeze/thaw cycle will typically kill ~50% of your viable cells.

So could this be corrected by making a small starter then stepping up to a big healthy one??

 

[altone]

my understanding (could be wrong) is that even under glycerol, you will lose somewhere around 10-20 viability each time you freeze/unfreeze the yeasts - so having them thaw out will knock them around a little but not finish them off.

I had no luck with the glycerol and freezing method - but I strongly suspect that was about a less than reliable fridge than any flaw in the idea.

Useless in a "frost free" freezer as they thaw out regularly.
Mine are packed in a styrofoam container filled with techni-ice packs to keep them frozen on the defrost cycle

Recently fired up a starter from a WY1318 stored that way for over 12 months.
tastes good so far.

I have used thawed yeasts in the past and they are much slower to build up to a decent pitch size
so obviously they don't like being refrozen much.