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Old 07-16-2008, 09:28 PM   #1
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Default Skimming kraeusen from a lager

I'm reading Gregory Noonan's book, "New Brewing Lager Beer"... In it he advises than the kraeusen should be skimmed after high kraeusen to prevent it from settleing back into the beer, which could impart a "harshness" to the finished beer. I have not heard much about this technique/philosophy and was curious if any of you skim the kraeusen. If so, how is this done? With what tool/implement? Any thoughts?

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Old 07-16-2008, 10:22 PM   #2
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Not sure what page you're reading, but I think he means only in open fermentation. It's just the oxidized scum that can contribute harsh flavors to the beer. In closed fermentation, you don't need to worry about it because the kraeusen isn't exposed to oxygen.

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Old 07-17-2008, 12:03 AM   #3
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ok...well that might be the case then. I was reading the portion on "Late Kraeusen" on page 184. But what you're saying makes sense. As you said he may have been referring to open fermentation.

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Old 07-17-2008, 02:55 AM   #4
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The kraeusen carries volatile oils in it that when not removed with the head are carried back down into the beer when the kraeusen falls, potentially causing off-flavors. I always remove the kraeusen from the head of my lagers using a big spoon. It usually forms several times and for this reason simply racking off after the first kraeusen forms is not sufficient.

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Old 07-17-2008, 12:37 PM   #5
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Quote:
Originally Posted by atarlecky View Post
The kraeusen carries volatile oils in it that when not removed with the head are carried back down into the beer when the kraeusen falls, potentially causing off-flavors. I always remove the kraeusen from the head of my lagers using a big spoon. It usually forms several times and for this reason simply racking off after the first kraeusen forms is not sufficient.
What is your source on this? "Volatile oils" are better known as essential oils. Where are these from, the hops? barley? Why would they cause harsh flavors? I would tend to disagree with skimming in closed fermentation unless you're trying to harvest yeast. The way Noonan explains it (pg 180, I think?) makes sense to me. Also, the risk of contamination alone is enough to sway me. I've never skimmed and I don't notice any harsh flavors in my lagers.
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Old 07-17-2008, 05:07 PM   #6
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and how would you do this if your using a Carboy?My lager didnt even make all that much kraeusen compaired to the ales I make

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Old 07-17-2008, 06:32 PM   #7
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you could ferment a 5.5 batch in a standard carboy (5 gal) so it's full to the neck, and put on a blowoff tube that fits inside the neck. It'll blow off into your bucket and be unable to fall back in.

I don't worry about it, though. I get stuff sticking to the walls of the 7gal carboy, and I leave it there.

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Old 07-18-2008, 02:16 PM   #8
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you could ferment a 5.5 batch in a standard carboy (5 gal) so it's full to the neck, and put on a blowoff tube that fits inside the neck. It'll blow off into your bucket and be unable to fall back in.
Sounds simple and elegant. Any drawback?
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Old 07-18-2008, 05:35 PM   #9
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Sounds simple and elegant. Any drawback?
Well, the extra bucket takes up some space in your fridge, or wherever you're fermenting. I've had it fill up a too-small container (a glass) that I was doing this into and spill all over the bottom of the fridge.

Works great though!

One time I sucked up the krausen with a sterilized racking tube attached to my shopvac. That was WAY to much work, but kind of fun. Although that batch of IPA was particularly good, who knows if it was related? Now I generally just do the blowoff hose with 5.25gal batches and sacrifice a beer or so worth of juice in the name of spewing out the krausen.
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Old 07-18-2008, 06:13 PM   #10
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Quote:
Originally Posted by menschmaschine View Post
What is your source on this? "Volatile oils" are better known as essential oils. Where are these from, the hops? barley? Why would they cause harsh flavors? I would tend to disagree with skimming in closed fermentation unless you're trying to harvest yeast. The way Noonan explains it (pg 180, I think?) makes sense to me. Also, the risk of contamination alone is enough to sway me. I've never skimmed and I don't notice any harsh flavors in my lagers.
That is also in noonans book... it is from the trub and fermentation. Page 142-155. 1986 edition. He indicates that not removing the first dirty krauesen it will allow it to fall back into the beer affecting stability. Oh - and I use a semi-open fermentation (it has a lid that just sits on top) not closed fermentation.

In any case - I think the chance of infection is over-rated. I regularly leave my unpitched wort in the freezer at 50 degrees for a week without any issues (just because of timing). I also skim my lagers with no issues.
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