reculturing yeast

[voodoochild7]

I have been reculturing some chimay yeast have just yesterday stepped it up a 3rd time. There is now visisble airlock activity and kreusen has begun. My question is how long to I have now to use it after it done. I have a 1.75 liter wine bottle about halfway full will this be enoght to pitch into my next brew?

 

[Baron von BeeGee]

I've stored yeast for 3 months in the fridge and re-used it without incident. Just make another starter to wake it up before pitching.

I usually pitch a minimum 2L starter into most beers (1045-1060 range is what I usually do). It really depends on the volume and gravity of your wort in terms of pitching what's optimal.

 

[voodoochild7]

So lets say this yeast is working when I brew on the weekend should I make a starter or just pitch what I have into the brew.

 

[Baron von BeeGee]

If it's actively fermenting I'd just pitch it in. Having said that, I'd pitch it in if you've taken precautions against oxidizing the starter (not shaking it vigorously). You'd like to know that the starter isn't going to contribute any off-flavors.

If it's fermenting now, I'd consider refrigerating it a couple days prior to brewing to settle out the yeast. Then you can decant/siphon the starter liquid off leaving just the yeast cake and you won't have to worry about the above problem. The yeast will be fine if they've only been in the fridge a day or two.

 

[chillHayze]

I have heard yeast begin to mutate randomly when you re-use the yeast cakes several times. That's the only way asexual organisims car evolve. Three was the magic number that I have heard. After the third time, I would say toss it.
However the thing about random mutation is that there is a possibility that the effects may be desireable. Now the odds of such an outcome, I do not know.

 

[Baron von BeeGee]

I think mutation is a bit overrated, though it definitely occurs. My plan is to re-use yeast until I get burned (haven't so far, but have only gone 4 generations with 1056). I think lots of commercial breweries go 10 or more generations, and in Warner's wheat beers book he says that German brewers who top crop Hefeweizen yeast go 100 or more.

I wonder if yeast mutates subtly, or if it just suddenly goes weird?

 

[chillHayze]

Yeah I think it is subtle, at least at first. If a stronger strain developes and takes over the weaker "stock" yeast entirely, you would notice a difference. Don't know the number of generations this would take. I have just heard 3 to be safe.

It would be a good experiment for someone who likes to drink the same style of beer every batch.

 

[Cheesefood]

Ohhh....X-Yeast. Yeast with Adamantium membrane. How cool would that be?

Of course, they'd be drunk all the time so probably not very fun. I imagine that they'd start a lot of pointless arguments with other yeast.

 

[Baron von BeeGee]

It would be a good experiment for someone who likes to drink the same style of beer every batch.

Actually, with 1056 you could brew a lot of different styles, especially APA's, IPA's, stouts, porters, etc. The Hefeweizen yeast is definitely more limiting. I've actually got some 1056 from last year that I'll probably try to revive for a batch in the next month or two. Walker is working on a 'house selection' of ales that would use a set # of yeasts...maybe he'll have some data at some point.

 

[Glibbidy]

5 is the magic number. Then things start to get freaky!

 

[Shambolic]

Surely you can't just say "1 batch of beer = 1 generation of yeast"?

 

[chillHayze]

Surely you can't just say "1 batch of beer = 1 generation of yeast"?

For our purposes, why not? When the little guys are done budding and subsequently, fermenting the beer for that batch they go dormant. Like rings on a tree my friend, rings on a tree...

Granted there are a ton of actual "generations" on one particular yeast's family in one batch alone. Difficult if not impossible to accurately predict. Taken literally, yeah I'm incorrect saying "generations."

 

[Levers101]

I would think another consideration with reusing a yeast cake would be the possibility for it to pick up nasty bugs along the way, and the possibility of that would increase with every subsequent brew.

 

[frothy]

I have heard yeast begin to mutate randomly when you re-use the yeast cakes several times. That's the only way asexual organisims car evolve. Three was the magic number that I have heard. After the third time, I would say toss it.
However the thing about random mutation is that there is a possibility that the effects may be desireable. Now the odds of such an outcome, I do not know.

Yeast can reproduce both sexually and a-sexually. When they reproduce they bud off exact copies of themselves in a-sexual reproduction. Two of these cells can however fuse together or "mate" as part of sexual reproduction to produce a heterozygous form (with two copies of each chromosome- these contain the DNA) resulting in far greater diversity.
this is a diagram but its even a bit beyond me I'm afraid -
http://www.dbsr.duke.edu/yeast/Info and Protocols/Life_Cycle.htm

So yes every time you brew a batch your yeast population will have undergone many many thousands of generations - each one produing increasingly diverse yeast. In the short term this shouldn't have an amazing effect on your beer as the lab strain you pitched to begin with is the only "sexual variety" available. If you were to say mix that strain with another you would of course see some significant differences after a few batches as the characteristics of each strain fuses. All in all I'd say that you'll have problems with contamination many months before your yeast becomes anything significantly different from what you first bought in the packet.

Don't know if you've seen them close up before but this is a little 1.4Mb movie
1000x magnification
http://www-micro.msb.le.ac.uk/video/Scerevisiae.mov

Matt