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General Category => Yeast and Fermentation => Topic started by: Kaiser on February 14, 2010, 05:21:47 AM

Title: Kraeusen removal, what difference does it make
Post by: Kaiser on February 14, 2010, 05:21:47 AM
Based on the discussion we had here: http://www.homebrewersassociation.org/forum/index.php?topic=486.0

I made an experiment where I brewed my Altbier with and w/o removal of the bitter Kraeusen gunk. To me the result is clear: I'll stick to Kraeusen removal for all beers since the one where the Kraeusen fell back has a very unpleasant finish for me.

Here is a write-up: Should the Kraeusen fall back into the beer?  (http://braukaiser.com/lifetype2/index.php?op=ViewArticle&articleId=134&blogId=1)

Kai
Title: Re: Kraeusen removal, what difference does it make
Post by: dhacker on February 14, 2010, 02:06:40 PM
Thanks Kai. Nice writeup.

Now as this is taken to the next level, the question arises, do all the different yeasts introduce different degrees of harshness from the braun hefe? 
Title: Re: Kraeusen removal, what difference does it make
Post by: weazletoe on February 14, 2010, 02:16:07 PM
Would I be able to spoon off the krausen, each day during heavy fermentation?
Title: Re: Kraeusen removal, what difference does it make
Post by: Kaiser on February 14, 2010, 02:23:52 PM
Would I be able to spoon off the krausen, each day during heavy fermentation?

I don't think it needs to be done each day. Removing it after the end of active fermentation  should suffice.

Now as this is taken to the next level, the question arises, do all the different yeasts introduce different degrees of harshness from the braun hefe? 

I don't think it has much to do with the particular yeast strains. But I could be wrong.

Kai
Title: Re: Kraeusen removal, what difference does it make
Post by: Hokerer on February 14, 2010, 02:48:59 PM
In your "convinced that the Kraeusen needs to be skimmed or blown of", I assume the "blown off" part refers to us carboy types.  How much headspace do you think it best to start with to get the correct amount of krausen blown off without blowing off too much other stuff (if that's possible)?  Since I usually do 5.5 gallons into the primary and I just got a six gallon Better Bottle, I think I'm probably good to go.
Title: Re: Kraeusen removal, what difference does it make
Post by: Kaiser on February 14, 2010, 03:14:38 PM
How much headspace do you think it best to start with to get the correct amount of krausen blown off without blowing off too much other stuff (if that's possible)? 

That seems to depends on the vigor of the fermentation. I have been using 5 gal carboys and would leave about 2 qt head space for lagers and maybe 3 qt for ales. 5.5. gal in a 6 gal better bottle should work. A lot of the gunk is not blown off exactly. It ends up sticking to the sides of the carboy or better bottle which also works in keeping it from falling back into the beer.

Kai

Title: Re: Kraeusen removal, what difference does it make
Post by: Hokerer on February 14, 2010, 03:21:28 PM
Edit: been fixed
Title: Re: Kraeusen removal, what difference does it make
Post by: Kaiser on February 14, 2010, 03:39:32 PM
This is how the top of my Maibock looks on the 7th day after pitching:

(http://braukaiser.com/images/misc_forum/97_Maibock_Kraeusen_day_7.JPG)

I'll remove that brown stuff before I rack the beer to a keg sometime next week. As long as there is CO2 forming the Kraeusen won't fall back.

Kai
Title: Re: Kraeusen removal, what difference does it make
Post by: NorthernIke on February 14, 2010, 03:55:38 PM
I wonder if this would work to remove the gunk from the kreusen?

http://www.aleiens.com/video/top-cropping-yeast-from-a

I'll have to try that...
Title: Re: Kraeusen removal, what difference does it make
Post by: Kaiser on February 14, 2010, 04:06:54 PM
I wonder if this would work to remove the gunk from the kreusen?

http://www.aleiens.com/video/top-cropping-yeast-from-a

I'll have to try that...

Not unless the Kraeusen is allowed to reach the top and stick to the sides.

Kai

Title: Re: Kraeusen removal, what difference does it make
Post by: a10t2 on February 14, 2010, 04:58:58 PM
It's interesting that you mention that several people couldn't differentiate the samples. I tried this with a split batch of hefeweizen a couple years ago and couldn't tell the difference at all. I wonder if, whatever the bitter compound is, it's one of those flavors that's right around the taste threshold and only detectable by some people.
Title: Re: Kraeusen removal, what difference does it make
Post by: denny on February 14, 2010, 05:22:05 PM
I appreciate your time and effort to do the experiment, Kai.  I've gotta say that your results remind me of several experimental results I've gotten....kinda inconclusive.  I think the bottom line is that if you feel it makes a difference, you should do it.
Title: Re: Kraeusen removal, what difference does it make
Post by: bluesman on February 15, 2010, 01:29:51 AM
Very interesting and enlightening experiment Kai.

Nice work!  8)
Title: Re: Kraeusen removal, what difference does it make
Post by: cpprice on February 23, 2010, 06:50:29 PM
What is the best way to remove the Kraeusen from a carboy?
Title: Re: Kraeusen removal, what difference does it make
Post by: blatz on February 23, 2010, 06:54:59 PM
What is the best way to remove the Kraeusen from a carboy?

allow it to blow off.
Title: Re: Kraeusen removal, what difference does it make
Post by: Kaiser on February 23, 2010, 07:20:47 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
Title: Re: Kraeusen removal, what difference does it make
Post by: dhacker on February 23, 2010, 07:41:22 PM
So Kai . . is this now SOP for all your batches?
Title: Re: Kraeusen removal, what difference does it make
Post by: Kaiser on February 24, 2010, 01:00:26 AM
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
Title: Re: Kraeusen removal, what difference does it make
Post by: bluesman on February 24, 2010, 02:59:27 AM
Have you checked the pH of the final product to see the effects of removal on the final pH of the beer.
Title: Re: Kraeusen removal, what difference does it make
Post by: Kaiser on February 24, 2010, 03:02:12 AM
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
Title: Re: Kraeusen removal, what difference does it make
Post by: blatz on February 24, 2010, 03:09:08 AM
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.
Title: Re: Kraeusen removal, what difference does it make
Post by: Jeff Renner on February 24, 2010, 02:48:45 PM
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.
Title: Re: Kraeusen removal, what difference does it make
Post by: blatz on February 24, 2010, 02:57:57 PM
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?
Title: Re: Kraeusen removal, what difference does it make
Post by: dean on February 24, 2010, 03:02:10 PM
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?
Title: Re: Kraeusen removal, what difference does it make
Post by: dean on February 24, 2010, 03:05:29 PM
This kinda begs the question though, what happens to the braunhefe if you use fermcap?   ???
Title: Re: Kraeusen removal, what difference does it make
Post by: Kaiser on February 24, 2010, 03:05:51 PM
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
Title: Re: Kraeusen removal, what difference does it make
Post by: dean on February 24, 2010, 05:27:14 PM

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!! 

Title: Re: Kraeusen removal, what difference does it make
Post by: denny on February 24, 2010, 06:03:21 PM
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.
Title: Re: Kraeusen removal, what difference does it make
Post by: Kaiser on February 24, 2010, 06:40:21 PM
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
Title: Re: Kraeusen removal, what difference does it make
Post by: bluesman on February 24, 2010, 07:42:38 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?
Title: Re: Kraeusen removal, what difference does it make
Post by: Kaiser on February 24, 2010, 07:55:21 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.  ^^^^^

Check the last row of the table in the write-up. w/o kraeusen removal the beer pH was 4.31 and w/ kraeusen removal it was 4.18. But I don’t know if that was affected only by the removal of the bitter Kraeusen. It is possible that the removal of yeast from the beer didn’t cause the pH to rise as much after fermentation slowed down. I wouldn’t put too much into this difference since I had beers with a similar difference and they tasted virtually the same.

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

No. I can’t test for IBUs and don’t plan to pay for it and I can’t analyze the beer components either. Our palate is all that we home brewers have.

Kai
Title: Re: Kraeusen removal, what difference does it make
Post by: ndcube on February 24, 2010, 08:02:29 PM
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?

I would think the yeast and braun hefe near the sides would stick and the stuff in the middle (which is most of it) would not.  Do you think that the yeast moves the braun hefe to the sides from the center during fermentation?
Title: Re: Kraeusen removal, what difference does it make
Post by: Kaiser on March 22, 2010, 02:51:19 PM
Just a quick update on this:

When I tasted the two beers again one month after the initial tasting I could still notice the difference but they were more similar than they were before. At this point I would not be surprised if tasters can’t tell a difference. Especially if they don’t know what to look for.

Kai
Title: Re: Kraeusen removal, what difference does it make
Post by: denny on March 22, 2010, 03:16:40 PM
Thanks for the update, Kai.  I find this a very interesting topic!
Title: Re: Kraeusen removal, what difference does it make
Post by: majorvices on March 22, 2010, 03:42:16 PM
Somehow I missed this conversation. Anyway, a few years back there was a homebrewing "how to" website that showed a bunch of young brewers introducing the world to their particular (and in some cases extremely peculiar) practice of brewing. It was passed around on a couple of forums, mostly for the laughs, particularly for one practice that they used to remove the "braun hefe" - they sucked it out with a shop vac!!

Now, I was probably the only one on the forums who actually thought this was a clever idea and I kind of contemplated doing it myself (with a new shop vac, not the one I use to suck the gunk out of my keggerator). Technically, if that was all you used it for and you kept it clean it should be fairly sanitary.
Title: Re: Kraeusen removal, what difference does it make
Post by: babalu87 on March 22, 2010, 03:50:53 PM
I suppose one could suck up some water with the shop vac when they were done to eliminate a science experiment in the shop vac.

I've taken to encouraging blow-off (using 6 gallon carboys as primary) and have noticed much smoother bittering but it really needs a side by side test that I havent done yet.

Lots of the brau hefe (brown gook) stuck to the concave part of the carboy.

Made an all Columbus IPA recently and its about the smoothest one I remember making with so many hops in it.