Should the Kraeusen fall back into the beer?

[Kaiser]

I already posted this a wile back on the AHA board but didn’t get around posting it here until now.

I did an interesting experiment aimed at indentifying what difference it makes if the brown Kraeusen gunk is not allowed to fall back into the beer:

[URL="http://braukaiser.com/lifetype2/index.php?op=ViewArticle&articleId=134&blogId=1"]Should the Kraeusen fall back into the beer?[/URL]

In my case it pretty much made the difference between a drinkable beer and a likely dumper.

Kai

 

[Edcculus]

Awesome writeup Kai!

I remember listening to a Craftbrewer Radio podcast about this a while back. They suggested that every brewer should taste the brown krausen, then deem if they really wanted that in their beer. I took their advice, and it tastes like absolute ****. Since then, I've been skimming.

 

[Kaiser]

This is one of the techniques which may not have been explored as much in the home brewing community. There are benefits to letting a beer take its time and wait until the Kraeusen has fallen completely. In particular this keeps you from racking the beer too early. As a result only few brewers would think about questioning this since changing it may require any of the following:

- fermenting in a smaller carboy
- opening a bucket an messing with the beer (the fear of infection comes to mind here)
- racking a beer before it looks completely done (the fear of underattenuation and young beer off-flavors come to mind)

Which may require more work, a change of the usual procedure and possibly carries the risk of developing other problems. On the other hand, this additional work or procedure change may get you better beer or gain you an advantage in a competition. So, some experimentation with this may be in order even if you may then decide that it was not work the effort.

Kai

 

[Hermit]

Interesting indeed. I've wondered about moving to buckets for the first part of fermentation so I can top crop yeast anyhow. I just fermented a stout very low with Notty and would have been hard pressed to get much out of it at all though.

 

[ChrisS68]

I like to make Pilsners, so this is very interesting to me. My last Bohemian came out great, but did have a sharpness and aftertaste that was somewhat out of style. I figured I might have been a little heavy-handed with the hops, but this is something I'll definitely explore. Thanks!

Pardon my ignorance, but what is the process of skimming? Is all the foam removed from the surface of the beer? Thanks again!

 

[SpanishCastleAle]

I noticed it so I started filling my carboys to a level that they either just barely blow-off OR almost blow-off (it's a fine line). Either way the gunk gets stuck to the cone/neck area of the carboy and doesn't fall back into the beer.

 

[Kaiser]

My last Bohemian came out great, but did have a sharpness and aftertaste that was somewhat out of style.

Yes, definately give this a try and let me know if it solved your problem or not.

Pardon my ignorance, but what is the process of skimming? Is all the foam removed from the surface of the beer? Thanks again!

With lagers I end up removing all the foam since they don't have the yeast head that ales have. Unless you see that the foam starts to fall back into the beer you don't have to skim them very often. Once after high Kraeusen might be fine.

Kai

 

[ChrisS68]

Very cool. Planning a Marzen so I might try it on that. Though the results won't be back for a while... sounds like I need to do a Pilsner too!

 

[GilaMinumBeer]

Sorry Kaiser, I have only had time to glean over your blog on the subject but, I am curious if you have seen any correlation to claims that open fermentation results in a cleaner end product?

Given that many, if not most, open fermentation vessle geometries allow for a level of krauesen loss due to overflows.

 

[menschmaschine]

I recall reading this in New Brewing Lager Beer, but IIRC, Noonan sort of did a -you can, but you don't have to- scenario. But reading that made me wonder if it would really make a difference and I admittely chose not to out of convenience. So, thanks for posting this, Kai. 50% of my brews are German beers, so I'm always interested in tips to take them one step better.

If I were to do this, I'm thinking I would do it in 5 gallon Better Bottles with a blow-off tube. How much blow-off is expected? Would a gallon jug for the blow-off hold everything from 5 gallons of beer?

Would a 3-piece air-lock with 1/2" OD (3/8" ID) tubing work on a 5 gallon better bottle with a drilled rubber stopper be adequate, or would that be a risk of clogging the tubing and blowing the stopper off?

 

[SpanishCastleAle]

mensch,
You should be able to select a volume in a carboy that allows the gunk to stick to the inside cone/neck of the carboy. It doesn't have to blow-off, just choose a volume that straddles the fine line between blowing off and not blowing off. That way if it does blow-off it's just a tiny volume and even if it doesn't you still get the benefit of no gunk falling back in.

Also, I use a carboy cap and attach 3/8" ID tubing for blow-offs. The restriction in the carboy cap port is way smaller than 3/8" and it's never clogged. But I put fairly clear wort into the carboy, maybe a little cold break but that's about it.

 

[ForRealBeer]

I always plan my batches to account for blowoff in the primary, and that seems to work well. What krausen isn't expelled seems to stick to the top part of a glass carboy and little if any makes it into the secondary fermentation.

Really, it seems a no-brainer to me to eliminate this problem early on because it is a relatively easy thing to do.

 

[wildwest450]

If I were to do this, I'm thinking I would do it in 5 gallon Better Bottles with a blow-off tube. How much blow-off is expected? Would a gallon jug for the blow-off hold everything from 5 gallons of beer?

I just use the 6 gallon one and put 5.5 gallons in it or 6 gallons in a 6.5 carboy, it blows off every time. I use a gallon jug for blowoff with no problems.

 

[menschmaschine]

mensch,
You should be able to select a volume in a carboy that allows the gunk to stick to the inside cone/neck of the carboy. It doesn't have to blow-off, just choose a volume that straddles the fine line between blowing off and not blowing off. That way if it does blow-off it's just a tiny volume and even if it doesn't you still get the benefit of no gunk falling back in.

Also, I use a carboy cap and attach 3/8" ID tubing for blow-offs. The restriction in the carboy cap port is way smaller than 3/8" and it's never clogged. But I put fairly clear wort into the carboy, maybe a little cold break but that's about it.

Thanks, SCA. I just don't know how well that would work for me. With my system (Sanke boil kettle) and a 90 min. boil, I can only end up with so much volume in my 6 gallon Better Bottles. It seemed to have a better chance of consistency using 5 gallon BBs and trying to blow it off and still getting roughly 5 gallons out of each fermenter.

You're right about the wort clarity though. I probably wouldn't think of using a 3/8" ID tubing as blow-off if I used plug hops and got a few pedals in there. Having a little pellet hops in there would hopefully be alright to get through the blow-off tubing OK.

 

[bob1852]

Good write-up as always Kai.

I brew mostly PA and IPAs, so I'm looking for bitterness - but I will anecdotally note that I brewed a brown ale recently and had a huge blow off (my boil off rate was lower than planned). The resulting beer was much less bitter and cleaner than the same brown I had brewed before without a blow-off (and dropped krausen). Of course there could be lots more variables in this case, but interesting to note none-the-less....

 

[SpanishCastleAle]

I just don't know how well that would work for me. With my system (Sanke boil kettle) and a 90 min. boil, I can only end up with so much volume in my 6 gallon Better Bottles. It seemed to have a better chance of consistency using 5 gallon BBs and trying to blow it off and still getting roughly 5 gallons out of each fermenter.

LOL, it wasn't but a month after I purchased my second 6 gal carboy that I went back to using the 5 gal carboys for this very reason!

One time I had a naturally carbing lager expand in the keg and get all up into my spunding/gage assembly. I decided that very moment that I didn't need to be using a 6 gal carboys for 5 gal batches.

 

[menschmaschine]

LOL, it wasn't but a month after I purchased my second 6 gal carboy that I went back to using the 5 gal carboys for this very reason!

One time I had a naturally carbing lager expand in the keg and get all up into my spunding/gage assembly. I decided that very moment that I didn't need to be using a 6 gal carboys for 5 gal batches.

Good to know! I have 4 ported/valved BBs... two 6-gallon and two 5-gallon. Until now, I've only used the 5 gallons for secondary/lagering. Looks like I just got 2 more primary fermenters for free!

 

[beesy]

good write up and good insight. well put together report. please don't take offense, but it appears you did not conduct a scientific experiement and you can't say for sure the krausen had any affect on flavor. you're a smart guy so i;m assuming you recognized this when you started. There are tons of things here that would negate this being an experiement in which you could confidentally say the krausen caused off flavors. Two seperate batches, the many small differences in things such as ph's, hop amounts, yeast and pitching rates, lengths of time: all these things could, and will, affect the outcome. i think we need to challenge you to do it again with a split batch, treating each sample exactly like the same and see what the results are.

 

[ChrisS68]

good write up and good insight. well put together report. please don't take offense, but it appears you did not conduct a scientific experiement and you can't say for sure the krausen had any affect on flavor. you're a smart guy so i;m assuming you recognized this when you started. There are tons of things here that would negate this being an experiement in which you could confidentally say the krausen caused off flavors. Two seperate batches, the many small differences in things such as ph's, hop amounts, yeast and pitching rates, lengths of time: all these things could, and will, affect the outcome. i think we need to challenge you to do it again with a split batch, treating each sample exactly like the same and see what the results are.

Who the heck is "we"? This is HomeBrewTalk, not the New England Journal of Medicine.

 

[BuzzCraft]

Al Korzonas did some relevant experiments documented in:
"When fermentation rears its dirty head", Brewing Techniques; 1996; 4(3), 50-54

He split a single batch into 4 fermenters, fermented with 2 different yeasts and used a blow off one one fermenter of each yeast batch while the krausen was allowed to drop back into the fermenter in the other.

The only significant finding in double blind taste testing by BJCP judges was a reduction in perceived bitterness. Samples sent to the Siebel Institute of Technology confirmed a reduction in bitterness ranging from 13-17%.

His suggestion was to increase bittering to compensate for this loss.

 

[dstar26t]

I thought I read this before...
Second paragraph under astringent

 

[Hermit]

Al Korzonas did some relevant experiments documented in:
"When fermentation rears its dirty head", Brewing Techniques; 1996; 4(3), 50-54

He split a single batch into 4 fermenters, fermented with 2 different yeasts and used a blow off one one fermenter of each yeast batch while the krausen was allowed to drop back into the fermenter in the other.

The only significant finding in double blind taste testing by BJCP judges was a reduction in perceived bitterness. Samples sent to the Siebel Institute of Technology confirmed a reduction in bitterness ranging from 13-17%.

His suggestion was to increase bittering to compensate for this loss.

So the 'gunk' might be the hop oil?

 

[LVBen]

Doh! I bought a 6 gallon plastic carboy because of all of the people posting "get the 6-gallon for 5-gallon batches so you don't get blowoff", but I guess it shouldn't matter too much since I picked up a 5-gallon glass carboy for $5, so I have a 5 and a 6, and also I plan on doing lots of bitter beers, so maybe the krausen in the 6-gallon carboy will get me a boost of that good bitterness...

 

[beesy]

Who the heck is "we"? This is HomeBrewTalk, not the New England Journal of Medicine.

This isn't the New England Journal of Medicine? I guess I'm on the wrong site.

 

[BuzzCraft]

So the 'gunk' might be the hop oil?

at least part of the "gunk" is hop residue.

if there truly is a difference in the quality of the perceived bitterness when comparing these methods and since a fair amount of the polyphenols in the wort comes from hops, one could surmise that the difference in bittering quality might be due to hop polyphenols being preferentially accumulated in the krausen and carried away in the blow off.

since the polyphenols in hops come from the woody part of the hop cone, i can imagine the brown residue in the krausen containing these undesireables.

 

[ChrisS68]

This isn't the New England Journal of Medicine? I guess I'm on the wrong site.

Touche!

 

[Kaiser]

There are tons of things here that would negate this being an experiement in which you could confidentally say the krausen caused off flavors.

I do understand that this experiment is fairly easily challenged. It's two batches and even though I do have fairly good control on the process parameters they were not exactly constant. Even the tasting turned out inconclusive for most.

But that is as good as I can do and I find it sufficient. In the end I'm just a home brewer and this is just a hobby. I also don't claim that I can for sure say that it must have been the fallen Kraeusen that made one beer worse than the other. However, based on my experience with previous experiments it takes more than the differences in pH and yeast propagation to cause significant taste differences. I'm convinced that the Kraeusen is to blame and many literature sources agree with me.

So, if you don't feel that letting the Kraeusen drop makes a difference in the quality of the beer you don't have to follow that advice. But I guess that a few brewers may get out of their way and give this a try which should give us a bit more data.

Kai

 

[remilard]

I was going to point out that skimming may reduce the bitterness but was beat to it.

I don't know how to control for that without isomerized alpha acid extract (accessible to the) and a lab (notsomuch).

I've tasted krausen and it mostly tastes bitter to me so I think the argument that if I tasted it I wouldn't want it in there makes as much sense as the argument that if I tasted a hop pellet I wouldn't want it in there.

That said, assuming you adjust for the potential loss in bitterness, I can't see how it hurts and a lot of people who have done more controlled experiences than kaiser have come to the same conclusion.

With some co2, a carboy cap and a racking cane you can get the brown krausen out of the carboy pretty quickly, while you are in there you can collect some white stuff (top cropping).

 

[pjj2ba]

Kai, how old were the beers when served? I'd be very curious to hear if the flavor of the one where the krausen was allowed to fall back in mellows with time. If this is the case, then this might suggest that if you want a brew to drink quickly, remove the krausen, but if you are going to age it longer, then it might not be an issue.

I typically do not "remove" the krausen any more, but I do use Fermcap and ferment in 5 gal. carboys, usually filled quite full. I typically end up with a lot of gunk stuck to the top of the carboy, more than one who uses a bucket would get. I haven't had a harsh bitterness in a beer in quite some time. I used to have problems with harsh bitterness and it would take a fair bit of aging to smooth them out (hence my question). Then I begain treating my water to reduce the high carbonates it has and the harshness went away. At the same time however is when I switched from using a blow-off to using the fermcap (and filling higher). But in my case, since I do get a ton of crap stuck on the top of my carboy, there might not be much of a difference between the two methods.

 

[BuzzCraft]

I like the approach the SpanishCastleAle and pjj2ba have alluded to. Having this stuff stick to the top of the carboy sounds similar to what some open fermentation breweries achieve when they have a lid over the fermenter that the krausen comes into contact with.

 

[ChrisS68]

A (non) update...
I intended to remove the kraeusen from a batch currently in primary. Had a pretty active fermentation for a couple of days before slowing down. Yesterday, airlock activity had ceased, so I removed the airlock/stopper and took a peek. From what I could see the kraeusen had already fallen. Guess I'll have to catch it earlier next time.

 

[Beernip]

Interesting experiment Kaiser. I wonder if there is any correlation between this and the statements by fermcap that it increases your hop utilization by 10%. Since with the fermcap your are not removing the hop oil/gunk/bits that float to the surface with the kraeusen . Also if BuzzCraft's article is correct that letting the kraeusen fall increased bitterness by 13% we may have something.

Do you think that if you produced to batches again and use 10% less hops on the initial hops addition that you would come out with a closer match? Does the kraeusen leave an undesirable aftertaste or just a more bitter beer that could be accounted for in your recipe?

 

[Kaiser]

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

 

[gmtech825]

Kai, how old were the beers when served? I'd be very curious to hear if the flavor of the one where the krausen was allowed to fall back in mellows with time. If this is the case, then this might suggest that if you want a brew to drink quickly, remove the krausen, but if you are going to age it longer, then it might not be an issue.
QUOTE]


i was actually wondering the same thing.

 

[SC_Ryan]

I have two halves of a 11 gallon batch fermenting in two 7 gallon carboys right now. They've been going for three days now and the krausens are still up. I'm tempted to rack one of the halves from under the krausen to another vessel as an experiment. It's a low gravity low ibu (balanced) beer too so it may be a good one to experiment with. Anyone have a better idea for separating fermenting beer and krausen?

 

[Kaiser]

No, racking should work. You may also rack only a 3/4 gallons into a growler if you don't want to rack all the beer in the carboy.

Kai

 

[SC_Ryan]

Unfortunately the krausen had dropped in both fermenters before I got to them this evening. I'll have to try this with my next batch.