Refreshing Yeast Bank

[Keith81]

I'm going to start using liquid yeast this year and want to overbuild starters for future use. I'm trying to decide how many strains I'd like to keep. Fridge space is not a problem so the limiting factor is keeping viability at a decent level. I've read about slanting and freezing yeast and I don't think I'm ready to attempt either of those yet.

My question is: if someone has the time and motivation would there be any harm in making a small starter just to rebuild viable cell count? I was thinking 6 months from the last harvest date if I wasn't planning on using that strain soon. I don't have a decent LHBS near me so having a yeast bank is really appealing.

 

[Mike_kever_kombi]

I’ve used yeast that was a year old. Stored in mason jars in a fridge. I over build all my starters and save about 1/4 liter for storage. I just build them up when I am ready. Give yourself minimum of a week to build a year old yeast.

Some have been pretty dark tan and I have thought no way I could revive them, but they always come back.

Now a days, I just keep 6 of my regulars on hand, and don’t go much over 2 months before using a particular strain again.

 

[paneubert]

My question is: if someone has the time and motivation would there be any harm in making a small starter just to rebuild viable cell count?

This is pretty much what a lot of people who slant or freeze will do when they are getting to an age where they might be concerned. The real philosophical question then becomes what generation do you consider that yeast to be? Since it was never used for an entire week/multi-week ferment, is it still "pure Gen 1" yeast if you have periodically made a starter from it? Some say yes, some say no. Some say you need to eventually worry about genetic drift and mutations away from the "standard" that the yeast strain is supposed to perform to. My opinion is if you are making a starter from freshly purchased yeast and then making starters from that starter every 6 months, you have little to worry about until you have done that a significant number of times in a row.

 

[Pappers_]

As long as your sanitation practices are spot-on and you make a starter every time, I wouldn't worry about storing yeast for months. No reason to make a yeast starter just to store it, I think, just wait until you're ready to use it and then make a starter. Build up that starter if you're worried that you're still low on the cell count.

 

[Keith81]

Thanks everyone. I don't anticipate any strain getting to a year between uses so it looks like I'm best off just allowing time for stepping up for the older stuff.

 

[Gadjobrinus]

I'd be equally worried about mutations after that long. I can't see a scenario where that wouldn't happen. I could be wrong.

 

[Roadie]

I use liquid yeast and always overbuild starters for this purpose. After about 6 months of non-use I make a SMALL starter to feed the yeast.

 

[brewcat]

This is something I'm working on right now. Eventually I think I'll freeze cultures, but until then I'm thinking I'll build fresh yeast to ~200 billion cells. Then use one to build for beers and one to double the yeast. For me this avoids stepping up. Then continuously rotate until the yeast needs replaced.

I'm also contemplating storing under distilled water to extend shelf life. It may work better in a slant...

Right now I'm just trying to figure out best practices. Possibly extra equipment.