Continuous Yeast Starter

[jglazer]

All - I recently harvested some Conan yeast, stepped it up 4 times before pitching most of it into a clone attempt, then I estimated I was left with about 80 billion cells so I started stepping it up again until I reached ~443 billions cells for another big DIPA. I pitched that second starter with ~ 80 billion cells left and I want to continue stepping this up and using it for a few more beers/ciders...

Anyone have experience doing this? My concern comes from the generally excepted knowledge that you can only reuse yeast (from primary) a few times before it starts to do weird things, but if I am stepping up the yeast in a low gravity, controlled starter where I am not really stressing the yeast too much, can I just continue to step it up (slowly) and not have to worry about the yeast changing too much?

Thanks!

 

[funnycreature]

I am no yeast expert but with culturing of every cell-based organism you will eventually select for cells that will grow best under the existing conditions. If you have a pure culture that is usually not a big issue, only when you put stress on your culture, like during beer fermentation with temperature changes and decline of nutrients, oxygen etc. What I'm saying is that if you keep the yeast happy during the starter cultivation the selection pressure will be much less severe than making actual beer since you keep them in a log phase, optimally. Does that make sense?

 

[LLBeanJ]

What you're describing is becoming more and more common. I do this regularly, though I rarely use leftover yeast from a starter to brew two batches in a row. Typically, my leftover starter yeast goes into a sanitized mason jar with boiled and cooled water and is stored in the fridge until I need to make another starter. I've revived yeast that has been stored for as long as 8 months doing this. I'm sure over time it will mutate into something other than what you started with, but you can go for quite a while if you keep your sanitation in check. I'm still using yeast that was originally purchased over a year an a half ago.

 

[jglazer]

I am no yeast expert but with culturing of every cell-based organism you will eventually select for cells that will grow best under the existing conditions. If you have a pure culture that is usually not a big issue, only when you put stress on your culture, like during beer fermentation with temperature changes and decline of nutrients, oxygen etc. What I'm saying is that if you keep the yeast happy during the starter cultivation the selection pressure will be much less severe than making actual beer since you keep them in a log phase, optimally. Does that make sense?

Yep that makes sense. I assumed as long as I don't stress the yeast too much they will remain healthy for longer than I will need them for (6-7 different batches at most). I am hoping that yeast don't need a break during this growth phase. With beer they have a limited amount of nutrients to consume and only grow until it is depleted, but with a continuous starter they are constantly multiplying over a 5-6 weeks. I am cold crashing the yeast in between step ups for 24 hours to decant, so there's that rest at least.

 

[jglazer]

What you're describing is becoming more and more common. I do this regularly, though I rarely use leftover yeast from a starter to brew two batches in a row. Typically, my leftover starter yeast goes into a sanitized mason jar with boiled and cooled water and is stored in the fridge until I need to make another starter. I've revived yeast that has been stored for as long as 8 months doing this. I'm sure over time it will mutate into something other than what you started with, but you can go for quite a while if you keep your sanitation in check. I'm still using yeast that was originally purchased over a year an a half ago.

That's awesome. I will definitely be keeping this yeast around long term once I am done brewing with it in the next few batches.