Originally Posted by WoodlandBrew
True, stress does promote sporification and petite mutants, but it will take quite some time before you really see a difference.
I was reading "Brew Like a Monk" and learned that some brewers repitch up to 10 times. Rochefort uses their yeast four times for the 6, then four times for the 8 and then uses it in the 10. So it's been through four 8%ABV batches and four 9% abv batches before it is used for the highest gravity beer that they make.
Loss of the ability to flocculate is a common mutation, but I'm not sure I follow how "yeast washing" would leave you with the cells that flocculate well. If you are referring to the ricing procedure that is promoted by a sticky on this forum then that actually encourages selection of cells that do not floculate well.
Found an older Brew Strong podcast about yeast with some people from White Labs, Jamil, et. al, talking about, as you might imagine, yeast.
Anyway, the show is fairly pointless with little usable information and I was thinking that I had wasted about 57 minutes of my life listening to a bunch of stupid ****, when in the last 3 minutes, Jamil talked about Stone's repitching.
He said Mitch Steele told him that Stone tried repitching from low gravity to high gravity, like is the common mantra. However, they found that the viability was not good. Instead, they found they got the best viability from their stock IPA -- which comes in at about 7% ABV, high high IBUs, etc. And it is from the IPA tank they pull slurry and use it for all other beers in the plant.
The thought is that the yeast is uniquely adapted to the harsh (relative) conditions of the high IBU, higher gravity beer, and adapted to the geometery of the fermeter, the pressure, etc, and it adapts to the unique environment and makes good beer.
In other words, the Stone IPA is like Navy Seal / Airforce PJ school all rolled into one and the all the limp wristed yeast that can't hack it don't survive so you end up with this ultra badass ninja sniper parajumper yeast that can ferment anything.
At least that's what I got out of it.