Top Cropping Process

We are still top cropping yeast, though we no longer use Ringwood in any of our beers. For our process, we allow fermenters to go beyond the high krausen stage before we harvest. Once a thick yeast blanket has settled on top of the beer (generally at terminal gravity or 2 Plato above terminal), we will harvest into a storage vessel with cooling jackets. We continue to monitor yeast viability in the storage tank, not seeing drastic degradation of viability till 7 or 8 days after harvest.

While you should see little to no mutation, it is important to keep track of generations and stay on top of any flavor shift. We have the benefit of a QA team that plates all open fermenters on a wild yeast media. If we see any growth, we will isolate yeast from that tank and not re-pitch it.

 

@C_Rockwood thanks for joining in, your input is appreciated.

 

IMO it's a touch high. Example: White Labs publishes a density ratio for each new batch they produce . . . you enter the lot number of the Purepitch packet and the "Yeastman" website gives the actual density of your purchase. Here's my latest packet:
https://www.yeastman.com/Login/Public/Report/PublicLabQCResult.aspx

EDIT: looks like you have to manually enter lot number (1066722).

They list an acceptable range of 2.0 to 2.8 billion cells per ml. In the example above my actual lot was 2.0B/ml, same as my previous lots . . . this being brand new yeast from supplier. While your 2.4 figure is the dead middle of what they call acceptable, your process is unlikely to be as efficient as WL's. Anyone ever bought a Purepitch that was higher than 2.0?