[majorvices]

3-4 for me. Sometimes I also just collect the slurry and make several starters off that slurry on my stir plate.

[denny]

I generally re-use my yeast.
I'm curious, assuming that the starter is the first generation, how many generations do others use?

At least 3, often 5, sometimes more.

[weithman5]

probably half dozen off a single starter. but i am still a fan of propagating/culturing part of what you buy so you will always have a first or second generation to use as a starter.  similar, if not easier, than culturing from sediment of a production beer.

[Matt B]

When I get a new vial, I usually make a starter, and split it into two bottles. One goes into storage, and I'll take the other one, pitch it, and pitch the remaining yeast cake maybe 3 or 4 times. After that I just get too nervous about contamination. And quite often I want to make a different beer that requires a different yeast. When I'm ready to go back to that original yeast, I'll take that second starter that went into storage, build that up and depending on how energetic I feel, I'll save some of that into another bottle that'll go into storage and pitch the rest, take that 3 or 4 times, etc etc. Needless to say, I don't buy yeast very often.

However, I realized that I had a couple of bottles of wlp007 in the yeast fridge. I haven't used that in a while, it went into the fridge August. Hmm. Probably dead, but heck, let's try to build it back up. Poured off the liquid, shook up the yeast on the bottom, poured it into a flask with a little bit of basic wort. Sat it on the stir plate over night. Next morning, looks nice and cloudy, was about to wash the yeast (since it had been sitting around for quite a while and there's probably tons of dead yeast in there that I didn't want to contribute to off flavors if I pitched it) and took a whiff .. WHOOOO. That isn't yeast that's growing in there. If you've ever done the off flavor tasting kit from Siebel, this is straight from the vial of ethyl acetate. If the girlfriend was around I would've had her put her finger in it and I'm guessing the nail polish would've dissolved right off. I'm not entirely sure what causes it, but needless to say, it went down the sink. And i've sanitized my equipment. Twice.

Lesson: If it doesn't smell like yeast. Don't use it. Six bucks for a fresh vial is worth not ruining a $20 batch of beer.

[a10t2]

Actual repitching, I've only gone three generations. I just don't brew enough to do it very often.

Propagating from a slurry though, I've re-used my 1056 culture 11 times so far, generally with several months in between. I don't consider that a new "generation" each time though, since it's only fermenting 1.030ish starter wort.

[mainebrewer]

Thanks for the replies.
On average, I brew every three weeks.
I alternate between WLP001 and WLP002 (occaisionally 005 or 007).
I've been filling a quart Mason jar after the initial ferment and then six weeks later using a portion of the jar.
I guess I'll start saving some slurry from the second and third ferment as well.
Assuming good sanitation, I wonder how long it would be before there was a negative effect from mutation?

[majorvices]

It depends on the  strain and gravity of the beer and how well you aerate... nutrients.... etc. I feel comfortable ~3 generations but not so much because of mutation, rather I feel less comfortable about the sanitation of the strain after that (either that or I am at a high gravity and I don't repitch from much higher than 1.070.)

[blatz]

I wonder how long it would be before there was a negative effect from mutation?

FWIW, I only get new yeast about twice a year (unless its a strain specific to the beer I'm making) I save from 1st and second pitches (which is actually 2nd and 3rd since i get brewpub yeast a lot) and then branch off of those to 4 generations, regrowing if I have to b/c its been too long.

so point is, you can go a good long while if you keep good sanitation practice and brew often enough to keep the yeast healthy.

[denny]

Assuming good sanitation, I wonder how long it would be before there was a negative effect from mutation?

Mutation takes quite a long time, AFAIK.  Sanitation is the real concern.

[b-hoppy]

back in the 90's i was doing 10 gal. each week.  on friday i'd rack, and saturday the new beer went right in on top of the dregs.  great for a couple months - then i noticed the beers were coming out more bitter than calculated.  freaked me out. (all i make is ipa's).  then, got working for the railroad, no schedule, on call 24/7 and what little time i have is precious - brewing was on the back burner.  couple years ago, things changed and i had some time to get back brewing and i also got one of these here fancy computers.  things changed in the homebrew world since my setback.  these forums saved my sanity when i saw a post about rinsing/washing yeast.  apparently my sanitation is o.k. because i'll run a yeast for 20 or 30 repitches or until i get the urge to change with no problems.  time is the concern.  i don't know when i'll be able to have some time to brew let alone make a starter, so having a couple mason jars filled with 'ready-to-go' yeast was a real blessing. sure, it'll get a little bitter after 10 or so batches of ipa but most of the time i'll brew a 'sissy beer' to give to my sissy beer drinking friends and when i harvest THAT yeast, it's like having a new/clean pitch.  i guess it all depends on your situation.

[mainebrewer]

Yeah, I really like having a jar or two of slurry in the 'fridge for those times when I find I can brew on short notice and don't have time to make a starter.
Of course, I keep a couple of packs of dry yeast around for the same reason. Gotta have a plan B!