how many times can yeast be re-built into another starter

[joegibs]

So, lets say I have a yeast that's hard to find, and I want to continue to use it for many batches down the line, but know I won't be able to get it at the homebrew store again any time soon, if ever. Say I also want to build it up to pull X amount out to share with friends to use. Starting from one single pack, is there any reason I cannot build a starter up several times, pull half out to save and store, then continue to re-build the other half with multiple stage starter to use and share and such? Basically, how far can a single store bought pack of yeast be built up? I'm guessing indefinitely assuming it doesn't get contaminated or let sit in storage for too long of a time period.

and to spill the beans, its the Wyeast 3463 Forbidden Fruit. Gonna make me some belgian wit and see how it goes with this yeast

 

[Tobor_8thMan]

I've repitched 5 times. That's my max. Of course, I didn't wait too long between brews.

 

[Golddiggie]

Look up how to safely freeze yeast and put some away that way. I know from experience it can go several years in that state safely. I actually have a starter going from the last of the tubes I had frozen, now. The lag time can be long for the first starter after it's been frozen. Second, and any after that, starter stages go fast (as normal). I'm hoping I can get enough yeast for a beer I want to brew this weekend. If it doesn't work as I wish, then I'll probably just shift the recipe to next weekend and brew it then. Provided I at least get the first starter to complete.

I'm working with the Wyeast 1882-PC which hasn't been available since before the start of last year. I hope they produce it again soon so that I can get a couple of packages. I'll treat one (might even do a starter to get a higher cell count) and freeze it in tubes. The other will be used. I'm harvesting the yeast from my batches (easy since I moved to conical fermenters) and pitching them in again.

If you do go the frozen route, then make sure you have enough tubes that you can build up your bank again (the ones in use) with just a single tube. I'd also be certain that you have at least a handful of really good samples saved (frozen) for future use. You can always use a tube to make more yeast that you can then freeze to return your frozen bank to a 'well stocked' status.

 

[IslandLizard]

Theoretically, indefinitely. Ask Wyeast or White Labs.
Practically, it may get infected at some point unless you can work in a sterile lab environment, etc. Or it may mutate slowly after so many propagations.

Every generation you propagate will contain a larger % of infection. So spread each generation out, wider.

For example:
1 pack > 2L starter > split into 5 and make a new 2L starter with each. Crash, decant and store each of those slurries in a small 4oz (jelly) jar under some saved starter beer. That's your stock. You can freeze some slurries in small centrifuge vials with glycerine added.

Over time, each of those 5 can be propagated to 5 starters again (total: 25 pitches). Use one of those for a batch. When you run low, make more starters for keeps.

Here's a good yeast calculator, I use mostly:
http://www.brewunited.com/yeast_calculator.php
You can also repitch a partial yeast cake from a batch. Use about 1/5-1/4 of a whole cake for a batch of similar size and gravity. Do not use yeast cakes from high gravity brews (say, over 1.070-1.080), and from very hoppy beers into low hopped beers.

 

[hottpeper13]

I make over build starters. Each pouch of yeast I get I make 1.5 L , save 250 ml in flask ,label and date and put in door of kegerator, then pitch the rest. The first beer is almost always a small beer of 1.040 or so. I'll repitch until i'm tired of it , around 4-5 times. My house yeast is 2565 and is almost 3 years old. I make a starter about every 3 mos.
Now I'm using Lutra as much as the 2565. And now lager season is creeping up on us......what yeast should I use this year,so many great choices.