Reviving old yeast stores

[mofox1]

I'm trying to work out the best way to revive old yeast stores that had their BB earlier in the year... (option 1 - brew more often!)

Assuming that most of the cells are dead, and I want to end up with 1 or two vials of fresh yeast to freeze, I realise that I can't (shouldn't?) just do a normal 3L starter, decant, vial, freeze, etc... because I'll end up with a good portion of the dead yeast in my "new" vials.

Current plan is:
- Do a 1 or 2L starter
- When active fermentation is visible, draw off a smallish sample (ie - 200ml or so)
- Use the sample to seed a 3L starter to build up enough new cells to put back into vials (possibley step from a 1L to 3L).

Any better methods about?

 

[Yob]

Could always rinse first, with the harvested yeast make your starter

 

[Online Brewing Supplies]

Best practice would be to plate it out on agar medium , select a good colony and start form there, thats good micro procedure.
The other way is to take your chances.
Nev

 

[siege]

won't the dead yeast cells be canabilised by the live ones when you do your starter? That has been my understanding and the reason I keep boiling the ***** yeast that comes with goop cans to use as yeast nutrient.

Also if there are dead cells left when your starter has fermented out won't they drop out first with the trub, so you could decant after 15min off the stir plate and assume what you've got is just healthy yeast?

 

[mofox1]

Could always rinse first, with the harvested yeast make your starter

Rinsing a 40ml vial... y'know, I never even would have considered that
Good thing I'm not talking about coopers/aust/dry english, because as far as I've seen it's the healthy yeast that drop first!

Best practice would be to plate it out on agar medium , select a good colony and start form there, thats good micro procedure.
The other way is to take your chances.
Nev

Whoa... That would be dedication to the cause! Curious as to why this would be better than doin a mini starter, and pitching a small amount of the active yeast into a fresh starter though. If I suspected a contaminated sample, and really *really* wanted to retain the strain, then I understand why this process is necessary, but what benefit does it pose to a low viability sample?

won't the dead yeast cells be canabilised by the live ones when you do your starter? That has been my understanding and the reason I keep boiling the ***** yeast that comes with goop cans to use as yeast nutrient.

Also if there are dead cells left when your starter has fermented out won't they drop out first with the trub, so you could decant after 15min off the stir plate and assume what you've got is just healthy yeast?

Canibilise... maybe. I just don't want 1/2 my "fresh" yeast actually the same old dead stuff I poured into the original starter.

As for the short rest and decant, I'd say you're on to something there. I should forget the small sample and just pitch the whole liquid portion into a fresh starter. Good pickup. B)

 

[Online Brewing Supplies]

Only because you select an un-mutated/infested mother colony to start again , it will show the deficiencies in the cells in an obvious way.
Requires no microscope just a keen eye. Yes its a bit of work but why waste your time making a suspect beer ?

 

[mje1980]

Since getting a stir plate I'm not too worried about year old yeast. I add some yeast nutrient and they come to life pretty good. If it's a small sample of a previous starter I'll step it up, but if it's a slurry I'll add 80ml of that to 1.5l starter with great success.

 

[Midnight Brew]

I found a packet of yeast that was 3 years old in my fridge. Its 2565 and took just over a week to swell up. Its had a little bit of a feed in terms of half gravity starters and will soon pitch it into a bigger starter to see what happens. Pretty interested to see what I can achieve from it in terms of age even though I have no plans on using it anytime soon. Just a small low cost experiment or it was going to go in the bin.

 

[Yob]

If it does fire up, freeze some off for me