Repitching Limits

[markcubed]

I've been hearing repitching yeast is a great way to save money and get consistency in your beers, but I've also heard it's only viable to repitch 5 or 6 times.

How can you keep a favorite beer on the same yeast strain indefinitely? Isn't that what commercial brewers do?

Thanks much

 

[COLObrewer]

Unlimited, you just have to invest in equipment/time/supplies for a yeast bank, You can probably find what you need by searching for yeast bank, saving yeast, etc.

 

[Gremlyn]

I just washed my first yeast cake and made five 1/2 pint mason jars. I marked each one as P1 (passage one), i.e. the number of times it has been used. Once I get down to my last jar, I'll repeat the process and make 5 more. I figure I can get at least 25 brews out of one yeast vial this way

I'm looking forward to getting a bigger place so I can have some room to setup a real yeast bank and start freezing them down for long term storage.

 

[Zen_Brew]

I think repitching indefinitely is a misnomer. Now obviously the mega breweries have their own team of scientists maintaining their yeasts. I have heard straight from the mouth of smaller brewers on Brew Network podcasts that the big yeast manufacturers like white labs and wyeast often keep custom stocks for the smaller breweries and the brewery gets a new batch sent in quarterly or on some other fixed schedule. So in this case it is obvious some smaller brewers limit the amount of times they repitch their own strain.

It is inevitable if you keep repitching that the strain will selectively mutate depending on the procedures used. While that isn't always a bad thing, it is different and if you are looking for maintaining a consistent product you don't want your yeast too far removed from the base yeast. Also at home we do not brew or store in sterile laboratory conditions so there is always a bit of this wild yeast, and a bit of that bacteria finding it's way into our stock. Eventually it is enough to alter the profile of the stock.

Probably the best way to get longevity from your yeast is to create a bank from the initial vial and freeze it. When it is getting a bit old you create another bank from a starter at generation +1. In this way you should be able to greatly extend the longevity from a single vial. Of course at $6-7 a vial many might argue it's easy enough to just get another vial after a period of re-use.

 

[eschatz]

The strain will eventually mutate as it's conditions change. Commercial brewerys are very observant of this and continually monitor the yeast. I and others have found that after about the third time of pitching your yeast kind of hit their sweet spot. After about 5 pitchings I usually start over. I still save a crap load on yeast doing this though. One thing to figure is that yeast have a hard time with higher alcohol so if you do a barleywine the yeast will be stressed and you don't want to save them. However if you ramp up to the barleywine you can get the most out of your yeast. Say do an American Pale Ale, then a Scotch 70/+, then an American IPA, and then an American Barleywine all on 1065 or nottingham or 001. Those beers would be good on that yeast. So you go from weakest (in alcohol strength) to heaviest and then finally discard your yeast.

Hope this helps. There's lots of info out there on yeast viability and repitching rates.

EDIT: What Zen said!

 

[ajf]

I buy a vial of yeast and make a brew from it.
When it comes time to keg or rack to secondary, I wash the yeast from the primary, and save it for future brews. This easily gives me enough yeast for another 4 brews using second generation yeast.
I also wash the yeast from each of those subsequent 4 brews, each time, collecting enough for yet another 4 brews. So far, that gives me 21 brews (1 + 4 + 16) from the one vial of yeast. If I wanted to (and had room to store it), I could repeat this process again, and get another 64 brews using 3rd generation yeast, but I usually end up by investing in another vial.
I have on occasion used 4th or 5th generation yeast, but I have also noticed that the yeast is mutating by that time, and produces different results to the first generation, so nowadays I never go over 3 generations.

-a.

 

[WorryWort]

ajf

your signature is one of my all time favourite jokes! I use it ever chance I get.

As for the yeast a commercial brewery I know uses about 6 gens. I read in BYO that breweries using open fermenters (Jolly Pumpkin was interviewed) can get a bit more. But I can't remember why.