Author Topic: Kraeusen removal, what difference does it make  (Read 4504 times)

Online Kaiser

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Re: Kraeusen removal, what difference does it make
« Reply #15 on: February 23, 2010, 12:20:47 PM »
Blowing it off is most practical. Another option is to rack the beer before the Kraeusen falls back into it. But then you may create other problems.

I simply stick a long piece of large diameter vinyl tubing into the neck. On the other end it is submerged in a large jar filled with water. Once the active part of fermentation is complete and the beer doesn’t blow-off anymore I replace the tubing with an airlock.

Kai

Offline dhacker

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Re: Kraeusen removal, what difference does it make
« Reply #16 on: February 23, 2010, 12:41:22 PM »
So Kai . . is this now SOP for all your batches?
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Re: Kraeusen removal, what difference does it make
« Reply #17 on: February 23, 2010, 06:00:26 PM »
So Kai . . is this now SOP for all your batches?

It has been even before this test. But now I feel stronger about this practice.

Kai

Offline bluesman

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Re: Kraeusen removal, what difference does it make
« Reply #18 on: February 23, 2010, 07:59:27 PM »
Have you checked the pH of the final product to see the effects of removal on the final pH of the beer.
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Re: Kraeusen removal, what difference does it make
« Reply #19 on: February 23, 2010, 08:02:12 PM »
After having stirred up interesting discussions of this subject with other home brewers I really had to test how well I can tell these two beers apart. Mostly to make up for the triangle test in which I failed to get all 3 sets correct I took 12 glasses, filled 6 with A and 6 with B. My wife then scrambled them and I took my time and palate cleansers to taste them all.

In the end I got 12 out of 12 correct. To be precise it is 6 out of 6 since I knew that each group had 6 glasses.

Following the discussion out there it almost seems as if I hit on another topic as controversial as decoction mashing. To bad that that didn't yield such clear taste results for me when I tried it.

Kai

Offline blatz

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Re: Kraeusen removal, what difference does it make
« Reply #20 on: February 23, 2010, 08:09:08 PM »
kai - I'm going to ask my pro buddy if he removes the braun hefe - I've never been around during fermentation so i'm not sure.  Would be interesting to note what his thoughts are.
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Offline Jeff Renner

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Re: Kraeusen removal, what difference does it make
« Reply #21 on: February 24, 2010, 07:48:45 AM »
The source of braunhefe and whether or not to remove it has been a matter of conjecture and discussion among homebrewers over the years on HBD and when we get together at meetings or NHC.

Based on the observation that I get more with a heavily hopped beer, and that the currently fermenting SS Minnow Mild (16.5 IBU) had nearly none, it seems pretty clear that it's at least partly from hops, maybe with some break material in it as well.  It has an almost waxy feel (presumably from hop resins) and is unpleasantly, and intensely bitter.

Over the years on HBD, some argued that if left in, it would impart an unpleasant, harsh bitterness to the finished beer, and other argued that if you removed it, you were removing some of the hops bitterness that you paid good money to get into the beer.

When the attendees of MCAB II visited the A/B pilot brewery in St. Louis ten years ago, the head brewer for that unit (whose name escapes me now) gave us a complete, behind the scenes tour.  This is a 15 barrel exact miniature of their regular breweries.  One things he pointed out was that the fermenter was designed so that the kraeusen rose exactly to the underside of the top, where the braunhefe stuck.  When the kraeusen fell, it left the braunhefe behind.  Of course, A/B has exact repeatability, so this works for them.

I do all of my ale fermentations in a cut-off Hoff Stevens 1/2 bbl keg, and when the very thin layer of braunhefe rises to the surface on the first or second day, I skim it off.  This is before the yeast rises (I almost always use a top fermenting yeast, most often WLP Essex).  This is mostly a habit based on these old discussions, though I'm not certain it's necessary, but see de Klerk below.

I ferment lagers in oversized carboys, so I can't remove it, but since I rack the beer into kegs when fermentation is still active but slowing, I can leave it behind as it floats on the surface of the little bit of foam that remains at this stage.

Here is what the only professional text (the 1957 standard reference "A Textbook of brewing" by Jean de Klerk) I have says:

On managing  top fermentations (pp. 409-410), "This brings us to the third stage of fermentation.  The head gradually falls in and finally forms a brown, bitter-tasting cover.  The brown colour of the cover is due to the oxidation of resins and tannins."  He then writes that you must rack to the conditioning tank when there is 0.8 - 1.0% fermentable matter left, and then "the cover of scum that forms at the surface is carefully skimmed off and discarded."

On managing top fermentations, he writes (p. 411), "Since the cover of dirty material on the surface cannot be skimmed off at the end of fermentation because it is mixed with the yeast, it is removed before the yeast starts to purge from the wort."

All that said, I don't think that all professional brewers do skim.
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Offline blatz

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Re: Kraeusen removal, what difference does it make
« Reply #22 on: February 24, 2010, 07:57:57 AM »
thanks jeff for the very detailed explanation.

Am I the only one who feels that a majority of the braunhefe remains stuck to the sides of my fermentor?  I certainly don't have a way to measure that, but eyeballing it, it seems that way:  I ferment about 11gal after kettle losses in a 14.5gal SS conical - with a hoppy beer there is a 2-3in ring of dark brown krausen stuck to the wall of the fermentor when I go to clean it.  Obviously, as Jeff pointed out, there is much less with say, my vienna.

Thoughts?
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Offline dean

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Re: Kraeusen removal, what difference does it make
« Reply #23 on: February 24, 2010, 08:02:10 AM »
I have it too Blatz.  After reading this thread I'm considering using a blowoff hose like Kai is talking about and seeing how it affects my beer.  Maybe some of the dry astringent bitter flavors I'm picking up is coming from the braunhefe?

Offline dean

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Re: Kraeusen removal, what difference does it make
« Reply #24 on: February 24, 2010, 08:05:29 AM »
This kinda begs the question though, what happens to the braunhefe if you use fermcap?   ???

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Re: Kraeusen removal, what difference does it make
« Reply #25 on: February 24, 2010, 08:05:51 AM »
Jeff,

Thanks for chiming in. It looks like I resurrected another HBD favorite.

Over the years on HBD, some argued that if left in, it would impart an unpleasant, harsh bitterness to the finished beer, and other argued that if you removed it, you were removing some of the hops bitterness that you paid good money to get into the beer.

Thanks for mentioning this argument. I’m aware of it and have thought about it: If removing the Kraeusen gives a better tasting product but requires more hops to get to the same level of bitterness isn’t it a no-brainer for a home brewer to take that hop utilization hit? We do it all the time when it comes to brewhouse efficiency and malt by not chasing 95%+ because of the risk of oversparging.

In addition to that I also tend to add my hops right before the wort starts to boil. This is before most of the hot break formed. But I have not yet tested how much this lowers hop utilization and if the quality of the bitterness is different.

Part of the “braune Hefe” are unisommerized alpha acids which become much less soluble as the pH falls. Those are pretty harshly bitter and there concentration is higher in wort that has been chilled quickly compared to wort that sat hot longer. I’m not sure how much this matters for this experiment though.

Kai

Offline dean

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Re: Kraeusen removal, what difference does it make
« Reply #26 on: February 24, 2010, 10:27:14 AM »

Part of the “braune Hefe” are unisommerized alpha acids which become much less soluble as the pH falls. Those are pretty harshly bitter and there concentration is higher in wort that has been chilled quickly compared to wort that sat hot longer. I’m not sure how much this matters for this experiment though.

Kai


Would overnight chilling help detract some of these particular polyphenols then?  I've been doing it for about the last 4 batches now and it does have less harsh bitterness but I'm not sure its from overnight chilling because I've also learned how to adjust my mash pH etc. at the same time.  I've got three carboys that are conditioning now, I've made different adjustments to each one but all have been chilled overnight.  I mainly use whole flower hops with an range of 3 to 6 ounces of hop additions including dry hopping.  I've wondered if its the whole hops and their age that contribute this as well as cloudiness in my finished brews.  So many things to consider... arghhh!! 


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Re: Kraeusen removal, what difference does it make
« Reply #27 on: February 24, 2010, 11:03:21 AM »
Wow, this is a great discussion!  Kai, your new tasting results, along with the info from Jeff, have me rethinking my stance on this.  I think I'll have to do some tests as soon as I have time.
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Online Kaiser

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Re: Kraeusen removal, what difference does it make
« Reply #28 on: February 24, 2010, 11:40:21 AM »
Wow, this is a great discussion!  Kai, your new tasting results, along with the info from Jeff, have me rethinking my stance on this.  I think I'll have to do some tests as soon as I have time.

Triggering a new round of experiments on this subject or at least closer attention to a possible connection between the removal of the Kraeusen gunk and harsh bitterness was the intent of this experiment. I want to be explicit about this since I understand that the write-up about my experience can easily be read as: “letting the Kraeusen fall into the beer makes bad beer -> if you don’t skim your Kraeusen your beer must therefore be bad”. This incorrect interpretation may have sparked some the criticism I have drawn.

I’m curious if more club members will be able to tell a difference if they know what to look for and if the setting for the tasting is less distractive. To me it made a difference.

Kai

Offline bluesman

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Re: Kraeusen removal, what difference does it make
« Reply #29 on: February 24, 2010, 12:42:38 PM »
Have you checked the pH of the final product to see the effects of removal on the final pH of the beer.

Kai, You never answered my question.  ^^^^^

Do you have a proof positive way of measuring the effects other than tasting which can be subjective?
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