How long will frozen yeast last in glycerin solution?

[rtstrider]

As the title says I have way too many tubes of frozen yeast in glycerin/distilled water. They are in a NON frost free chest freezer and are stored inside lunch boxes lined with gel pack walls and also have extra gel packs in the lunch boxes to keep temperature swings to an absolute minimum. The freezer stays between -20f and 0f. The chest freezer is inside the house to it is in a temperature controlled environment. With that said how long should I expect the frozen tubes of yeast to be viable? Are we talking 1-2 years, 5 years, 10 years, indefinitely, etc?

I’m definitely not opposed to lowering the deep freezer thermostat to run colder if needed. Sorry for the long winded post but I wanted to give some background that might help I’m better answering my question.

 

[Jaybird]

I have kept yeast in that state with great success for 2 years. After that it was iffy but I did re build a yeast strain I forgot about after 4 just to see if it would pop off. It did.
Cheers
Jay

 

[rtstrider]

I have kept yeast in that state with great success for 2 years. After that it was iffy but I did re build a yeast strain I forgot about after 4 just to see if it would pop off. It did.
Cheers
Jay

By iffy what issues did you run into? Did the yeast not ferment? Was the yeast stressed?

 

[Jaybird]

By iffy what issues did you run into? Did the yeast not ferment? Was the yeast stressed?

Slow to start and higher FG than I would have normally for that strain. Always fermented. Just not as fast and vigorous as it's fresh self. But that's just been my experience.

Cheers
Jay

 

[Golddiggie]

I had yeast frozen in 2012 remain usable until my freezer shat itself in April. I used some last year in a batch and it worked out as expected. I did do a few starter steps to ramp up the cell count to where I wanted/needed it for the recipe. I wanted to use the yeast again recently, after the freezer issue, but it didn't smell right in the second starter. So, I tossed it.
I'm hoping that the strain is released soon (it was a Wyeast Private Collection strain) so I can build my bank again.

IME, if you keep it frozen, at the temperature needed (get your freezer as cold as it will go) it will be good for a number of years. Just plan on making starters far enough from brew day to get it stepped up. IME, the first starter takes the longest to finish, even on a stirplate. In the area of two to three days. Each starter step after that takes off as you normally expect, finishing in about 24 hours.

 

[rtstrider]

I had yeast frozen in 2012 remain usable until my freezer shat itself in April. I used some last year in a batch and it worked out as expected. I did do a few starter steps to ramp up the cell count to where I wanted/needed it for the recipe. I wanted to use the yeast again recently, after the freezer issue, but it didn't smell right in the second starter. So, I tossed it.
I'm hoping that the strain is released soon (it was a Wyeast Private Collection strain) so I can build my bank again.

IME, if you keep it frozen, at the temperature needed (get your freezer as cold as it will go) it will be good for a number of years. Just plan on making starters far enough from brew day to get it stepped up. IME, the first starter takes the longest to finish, even on a stirplate. In the area of two to three days. Each starter step after that takes off as you normally expect, finishing in about 24 hours.

Absolutely! I use 15ml tubes and go with a 150ml 1.020 starter in a canning jar (no stir plate). That usually takes a few days (5-7) to ferment out. Once that's done I go to 1.5L 1.020 wort on the stir plate and again that can take a few days (3-4) to ferment out. Finally I give it a bump to 2L 1.040 and that's usually done in 48-72 hours. I try and plan my yeast buildup with a good 2 weeks lead time to brew day. Back when I started this project at the beginning of the year it was because I could only get Wyeast and very few Imperial strains in town. Here it's mostly Dry yeast, Wyeast, or bust. Being in FL we have a VERY short window that yeast can be shipped non overnighted and it be cool the whole trip. So I got a few White Labs and Omega strains shipped and banked them up. This was back in January. Funny story though. A brewery/homebrew shop is opening up within a 2 minute walking distance (if there's traffic) from my house. Owner said they can get whatever brand I want. So I'll probably use up what I have frozen just for learning purposes but purchase the liquid strains from them going forward.

 

[Golddiggie]

I'm using the canned Proper Starter to make my starters now. So they're in 1L increments. I'm done getting DME to make starters and all that crap.

I can't recommend getting a stir plate highly enough. Not only do the starters finish faster, but it's easier on YOU. You can shave the time the starters take to finish at least in half. Only frozen, or really old yeast in the fridge (5+ months IME) take more than 24 hours to finish on the stir plate. Then most are done within 2-3 days (tops) and ready to go to the next steps. I typically kick off a two step starter schedule about 5-6 days before brew day. That gives them a day (after each step) to chill in the fridge/keezer to settle more before the next step. Or before going into fermenter.

 

[nekrowizard]

I like your freezer setup. I've done this for cells at work and yeast at home. Mix the glycerol in as best you can, if you can get an old vortex to agitate your tubes, that would be awesome. No such thing as too many freezer stocks, every time you thaw cells it's kind of a crapshoot, even in a professional setting. You could get this to last for decades.

Set up a freezer temperature alarm if you can.

 

[deuc224]

Ive noticed my stock of 3068 takes a few days to wake up from the glycerin mix.

 

[hotbeer]

Probably depends on how much trouble you want to go to to fully revive them. Just read this about the day you made the post. Finally got around to looking for it.

https://www.bbc.com/future/article/...ed-yeasts-could-change-the-taste-of-your-beer