Top cropping techniques

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jmo88

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How do you do it?

I tried it today on a WLP037 Yorkshire Square fermenting. I'm not sure I did it right. I skimmed about half the krausen off the top but am not sure it's enough. I got about a full 12oz or so of foam that settled out in about 1/4 cup of sanitzed water in a canning jar. Now that the foam has dissipated and the thicker material has dropped, the slurry looks more like trub than healthy yeast.

Was I supposed to go deeper under the krausen to get a better top crop?
 
make a starter with it and see how it turns out. I have never harvested yeast this way so this is the only good suggestion I have.
 
So I researched this a little more and found this on the Wyeast website:

Wyeast Website said:
Harvesting yeast from the top of open fermenters (top cropping) is still a widely used practice in the modern brewing industry. Specific yeast strains which rise to form a dense head must be used, making top cropping nearly exclusive to ale and wheat strains. As with other methods of harvesting yeast, harvesting a consistent population which avoids the extremes is important.

Yeast should be harvested once fermentables have been reduced by 50% or more. The timing of the skim should be consistent from batch to batch to help maintain fermentation profile. A head will rise approximately 24-36 hours into fermentation. The first “dirt” skim containing trub should be discarded as should the final skim. The middle skim should be harvested and used.

This morning I skimmed the Krausen a second time and the foam bubbles were much finer and slurry like. Because of the first skim, the trub was gone. I went right down to the the level of beer. I feel good about it this time.

I'm going to make a starter with this on Thursday or Friday and brew up another batch on Sunday.

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Well I made a starter and with the top cropped yeast above and it looked like this in two hours.

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This was much more intense than the vial. In fact the vial didn't even krausen. Apparently top cropped yeast is 100% viable. These puppies were ready to eat.
 
I top cropped last night and dropped the krausen straight into a starter... my starter was going crazy in about 20 minutes. It pretty much looked like the one above after a couple of hours.
 
Top cropping strains are a breeze to work with. Yeast washing from the trub is a PITA. I plan on working with this same strain for a while because it's so easy
 
I have always had great results top cropping from my open fermenter. The yeast I "top crop," out performs the vial yeast every time. Its all about when you harvest, or skim. I have read that it is best to harvest when your apparent attenuation goes past 50%, but I just kind of feel it out. You want to leave enough yeast behind to finish the task at hand!
 
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