Dear Mr. Wizard,
I used some ready-to-pitch liquid yeast. A day after adding the yeast, the usual kraeusen formed on top, but it wasn’t "blown off" through the tube. After five days the kraeusen settled down quite a bit, and I racked to a secondary. Will the lack of kraeusen removal have a major effect on the flavor of my beer?
Dave Silver, Dallas
Mr. Wizard replies:
The topic of kraeusen removal is not discussed much in commercial brewing circles because most modern fermenters are not designed to remove kraeusen. And it is frequently the case that "blow over" creates an unwanted mess in the brewery. This is not to say that kraeusen removal has no effect on beer flavor. Some brewers firmly believe that kraeusen removal helps smooth out the flavor of beer. Anheuser-Busch has specially designed fermenters that remove the "braun hefe" (brown yeast) from beer during fermentation. The braun hefe is the trub-yeast-scum that floats on top of beer during fermentation. Many other brewers in the world have their own special way of removing braun hefe during fermentation. Every brewer should taste braun hefe just for grins; most of us will agree that it doesn’t taste all that good. This is one of the reasons that traditional methods of fermentation involved skimming.
It sounds like you remove the braun hefe by relying on an active and aggressive fermentation to blow it out of your fermenter. This method works well to push the brown crud out of your fermenter, but I doubt that it has a drastic effect on beer flavor. I think skimming is one of many techniques that are used to make subtle changes to beer flavor.
Most commercial brewers have gone to "uni-tank" fermenters over the last 20 years. Beer is fermented — usually without "blowing over" — and aged in the same vessel. During this time the kraeusen rises and falls, yeast cells grow and flocculate, and the beer goes from wort to aged beer. It makes a brewer wonder how many subtleties have disappeared because of this method of fermentation.
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