I spent a long time lurking and learning from everyone on the forum. I've searched the 26 pages of this thread but still have a question!
I've tried this twice now, and each time I get far less yeast in the vial than I think I should. There was so little the first time I dumped the vials. I have a batch in the pre-freeze refrigeration period now that looks marginally better, but I'm only seeing about 1/8 inch in most (I'm using 16ml vials). There still appears to be some yeast suspended, but I dont think there's going to be a significant increase.
I've been using a pipette to draw from the bottom of my starter flask. It looked good in the pipette, and it all stayed suspended in the vial initially.
I don't want to freeze a bunch of flat beer and glycerin holding a useless amount of yeast. I'm not clear on this: Should I be seeing a significant layer of yeast settling on the bottom like I do on my crash-cooled starters, and if so how deep might I expect it to be?
Thanks - not just for this, but for all the great info everyone shares!
None. The transition to a frozen state is what damages them.
Once frozen, they stay preserved best at the coldest temperatures (e.g., labs store yeast at around -80).
Yep, you won't be able to "overfreeze" them without some special steps. The freeze/thaw cycle just exposes them to more of the cell-wall bursting impact of water in the solution. This is why we use glycerin in the "preservation" steps prior to freezing. Additionally, once you get it frozen, as long as you keep it frozen, it will last just about forever. Long-term storage in -80C freezers is what labs generally do, Now, you won't get anywhere near that in a home chest freezer or side-by-side.
You want to take any and all steps to keep it from thawing during the auto-defrost cycles. Use heavy duty styrofoam insulated coolers and it's best if you can get your hands on the lab/medical grade ones. You can usually find them around hospitals, labs, etc and you can usually get them without much convincing.
First off, Flyguy you rock! Thank you so much for the great information.
I wanted to say that I followed the steps and made a successful frozen yeast bank. I just thawed and made my first starter and was wondering something. I went straight from my vial to about 1 litre of wort and put it on my stir plate and let it go. It fermented fantastically and once pitched it seems to be working great.
I was wondering if I made a mistake by going straight from the vial to 1 litre of wort rather than incrementing up. I read that someone else said it was alright and I realize I should have asked before I did it. I know I can just wait a couple weeks til bottling time and figure it out for myself I just thought I would see everyone else's experience and if I can just keep pitching from vial in the future.
I use 30ml vials and pitch them directly into 1L-2L of wort on a stir plate. I have no science for you, just saying that I've never had a problem with it. I'm not really sure what stepping up allows me. I figure if I'm continually aerating the wort on a plate, then the yeast are going to reproduce and eat sugar -- why not feed 'em a bunch of it?
Perhaps I need to find more info on stepping up a starter myself.
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Fermenting: A few beers
Conditioning: A few other beers
Bottled: A few more beers
Kegged: Many beers
Next Brews: More beers than you could imagine
From a vial, start with less wort. I wouldn't start with more than 0.5 L. Get the alcohol content built up as fast as possible in that starter to protect from bacterial infection. Larger wort = longer time to 2% alcohol = more risk. Step up, repeat until desired volume is reached.
First off, Flyguy you rock! Thank you so much for the great information.
I wanted to say that I followed the steps and made a successful frozen yeast bank. I just thawed and made my first starter and was wondering something. I went straight from my vial to about 1 litre of wort and put it on my stir plate and let it go. It fermented fantastically and once pitched it seems to be working great.
I was wondering if I made a mistake by going straight from the vial to 1 litre of wort rather than incrementing up. I read that someone else said it was alright and I realize I should have asked before I did it. I know I can just wait a couple weeks til bottling time and figure it out for myself I just thought I would see everyone else's experience and if I can just keep pitching from vial in the future.
They are 16ml vials btw.
Cheers
It really depends on how many viable cells are in that vial. How long has it been in storage and how many viable cells were in the original sampling (and quality of your technique)...
Step in measures of no more than 10x volume until you reach .5L or so and then in steps of 4x.
As pawn said, you want to get a good active fermentation going ASAP and don't overwhelm the yeast (and give bacteria a chance to gain a foothold).
With my method of using just scrapings of frozen cells, I have to go from a tiny starter (10 ml) and then step up from there.
If the samples are pretty fresh with a decent amount of yeast, I go from the vial to a 500 ml starter to whatever starter size I need. If they've been stored a while, I put in an extra step with a 150 ml starter.
I have had great success starting with a 125 ml (1/2 cup) starter from a frozen vial, then adding 500 ml more of wort, then another 1 L or so to get it to pitching strength.
The exact reason is not clear (I have asked around and not received a clear response, anyways), but you get a lot more yeast by stepping up in the manner above than by pitching a frozen vial directly into 1625 ml of fresh wort. You also make it more difficult for contaminants to take hold by stepping up, as well.
I have had great success starting with a 125 ml (1/2 cup) starter from a frozen vial, then adding 500 ml more of wort, then another 1 L or so to get it to pitching strength.
The exact reason is not clear (I have asked around and not received a clear response, anyways), but you get a lot more yeast by stepping up in the manner above than by pitching a frozen vial directly into 1625 ml of fresh wort. You also make it more difficult for contaminants to take hold by stepping up, as well.
I saw a reference to stepping up once that claimed something like 10x jumps until a certain point. Then it had to slow down some.
I saw a reference to stepping up once that claimed something like 10x jumps until a certain point. Then it had to slow down some.
Yep, it is four posts up on this page!
Seriously, that is what I had heard as well. This is apparently an empirical relationship, however, because I have yet to find an adequate explanation for it anywhere (by that, I mean an explanation of the mechanics of the process from which this pattern arises).
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