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General Category => General Homebrew Discussion => Topic started by: elipsis on November 27, 2009, 04:01:40 PM

Title: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: elipsis on November 27, 2009, 04:01:40 PM
I've started top cropping yeast from my ales using a blow-off tube to move the krausen into a sterile jar. After two or three days, I've collected around 200ml of pure yeast, which is sitting under a liter of beer. My procedure has been to pour the beer off the yeast, add some distilled water, swirl and transfer to a clear jar.

This is all working fine, but I've noticed that when I taste the beer that was sitting on top of the yeast, it's insanely bitter. I'd guess that along with the yeast and beer, hop residue is being pushed through the blow off tube.

My question is this: if the blow-off tube is removing bitterness from the beer, isn't it obvious that the beer left in the fermenter is less bitter? If I were to use an airlock instead of a blow-off tube all all that hop residue would settle back into the beer, increasing the overall bitterness. Has anyone ever quantified the effect of removing krausen on the overall bitterness of the beer?
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: tom on November 27, 2009, 05:01:57 PM
Yes, it's the "bitter kraeusen". It used to be the thing to do. How does your beer taste?
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: denny on November 27, 2009, 05:19:30 PM
I actually did some testing on this years back.  I found that removing the krausen had no effect on the perceived bitterness of the beer.  Nor did it have any effect on beer quality.  This was years ago in one of my earliest experiments.  I should probably try it again with a little more rigorous procedure.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: elipsis on November 27, 2009, 06:19:33 PM
I've made three beers this way. The two I've tasted so far, a dry stout and an IPA, are some of my best beers yet. There's a Scottish 80/- just about ready to keg that I've not tasted yet, but I have high hopes.

The interesting thing about the IPA is that I brewed it to 50 IBUs, which to my palette is very bitter, but the taste is much less assertive than I'd expected. I attributed this to the fact that I did FWH for the first time with this beer, but now I'm wondering if the bitter krausen removal had something to do with it.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: rep on November 27, 2009, 07:09:14 PM
I've made three beers this way. The two I've tasted so far, a dry stout and an IPA, are some of my best beers yet. There's a Scottish 80/- just about ready to keg that I've not tasted yet, but I have high hopes.

The interesting thing about the IPA is that I brewed it to 50 IBUs, which to my palette is very bitter, but the taste is much less assertive than I'd expected. I attributed this to the fact that I did FWH for the first time with this beer, but now I'm wondering if the bitter krausen removal had something to do with it.

Interesting process you bring up.  Be careful in making this conclusion though.  It is my understanding that when you use the FWH process, what you found is what is supposed to happen.

Therefore, I would be a bit careful in expounding that to the krausen process.  Maybe isolate the factors?
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: denny on November 27, 2009, 07:11:45 PM
I've made three beers this way. The two I've tasted so far, a dry stout and an IPA, are some of my best beers yet. There's a Scottish 80/- just about ready to keg that I've not tasted yet, but I have high hopes.

The interesting thing about the IPA is that I brewed it to 50 IBUs, which to my palette is very bitter, but the taste is much less assertive than I'd expected. I attributed this to the fact that I did FWH for the first time with this beer, but now I'm wondering if the bitter krausen removal had something to do with it.

Interesting process you bring up.  Be careful in making this conclusion though.  It is my understanding that when you use the FWH process, what you found is what is supposed to happen.

Therefore, I would be a bit careful in expounding that to the krausen process.  Maybe isolate the factors?

Took the words right out of my fingers, rep!
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: babalu87 on November 27, 2009, 07:28:12 PM
I plan on doing this with a German Pils in the near future.

One is getting fermented in a 5 gallon corney and the blow off is goin out the keg in the air-lock jug
The other is going in a 6 gallon carboy fermented as usual letting the krausen fall prior to racking.

I've been speaking with someone about this (my bet he'll chime in here soon) and he is leaning towards it making a difference on the smoothness of the bitterness.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: elipsis on November 27, 2009, 07:40:39 PM
I've made three beers this way. The two I've tasted so far, a dry stout and an IPA, are some of my best beers yet. There's a Scottish 80/- just about ready to keg that I've not tasted yet, but I have high hopes.

The interesting thing about the IPA is that I brewed it to 50 IBUs, which to my palette is very bitter, but the taste is much less assertive than I'd expected. I attributed this to the fact that I did FWH for the first time with this beer, but now I'm wondering if the bitter krausen removal had something to do with it.

Interesting process you bring up.  Be careful in making this conclusion though.  It is my understanding that when you use the FWH process, what you found is what is supposed to happen.

Therefore, I would be a bit careful in expounding that to the krausen process.  Maybe isolate the factors?

If I had the dedication to the craft of someone like Kai, I'd be in my garage right now preparing 6 one gallon batches, each of which varied from the others on a single parameters. In three weeks I'd be comparing the results, creating excel spreadsheets and performing regression analysis on the results.

But I'm me, so I'll just keep making beer and wondering why some is good and some is not.

:)
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: denny on November 27, 2009, 07:45:50 PM
I've been speaking with someone about this (my bet he'll chime in here soon) and he is leaning towards it making a difference on the smoothness of the bitterness.

Just make sure to do a fair tasting, like a blind triangle test.  Otherwise, a foregone conclusion like that could skew the results.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: babalu87 on November 27, 2009, 07:52:23 PM
I've been speaking with someone about this (my bet he'll chime in here soon) and he is leaning towards it making a difference on the smoothness of the bitterness.

Just make sure to do a fair tasting, like a blind triangle test.  Otherwise, a foregone conclusion like that could skew the results.

All my testing is blind  ;D
I'll ship him the bottles 
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: Kaiser on November 27, 2009, 08:52:27 PM
I'm always aiming to blow off the kraeusen. Most of the German authors I have been reading are very ademate (spelling) about that. They say that Kraeusen that falls back into the beet  can give it a harsh bitterness. But I haven't found the opportunity to make a side by side yet. I may end up doing this as a small scale batch. Until
I can evaluate this process parameter more closely I stick with blowing off the gunk.

This is one of the cases where I want to have data to justify my process but there are other things that I'm interested in more and which I'd like to test first. Hence the lack of experimentation with this on my side. 

Kai
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: beerocd on November 28, 2009, 03:29:29 AM
I thought I was gonna be real cool and link to a Zymurgy story about this. THE IOWA BEER TINKERERS by Paul Ogg. Seems to be the type of experiment being discussed here. Dec 2004 Vol 27.

Maybe one of the Mods here can dig it up?

Bottom line was, blowing off the Krausen made a more enjoyable beer when tested side by side - but when drinking the retained krausen beer by itself it was also acceptable beer.

-OCD
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: denny on November 28, 2009, 04:53:36 PM
Maybe one of the Mods here can dig it up?

I just shot off an email to see if we can add it to the downloadable Zymurgy articles.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: Kaiser on November 28, 2009, 05:06:29 PM
Maybe one of the Mods here can dig it up?

I just shot off an email to see if we can add it to the downloadable Zymurgy articles.

cool. Thanks.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: corkybstewart on December 12, 2009, 03:20:39 PM


[/quote]

If I had the dedication to the craft of someone like Kai, I'd be in my garage right now preparing 6 one gallon batches, each of which varied from the others on a single parameters. In three weeks I'd be comparing the results, creating excel spreadsheets and performing regression analysis on the results.

But I'm me, so I'll just keep making beer and wondering why some is good and some is not.:)
[/quote]
I'm right there beside you.  I'll experiment with using different yeasts for the same batch of wort, but that's as scientific as I get.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: beerocd on December 13, 2009, 05:32:48 AM
still not in the archives.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: dhacker on December 13, 2009, 01:36:38 PM
Great thread . .one that I hope continues for awhile as data points are added. I too am anxiously awaiting the link to the aforementioned article.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: denny on December 13, 2009, 04:50:42 PM
still not in the archives.

I'll try again.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: MDixon on December 13, 2009, 10:05:56 PM
Based upon the data presented in Hombrewing Vol. 1 and a Brewing Techniques article where the IBU were measured bitterness is reduced when blowoff occurs.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: beerocd on December 15, 2009, 05:56:04 PM
Denny,
Can I just scan it and post it? Can't see how it violates copyright if I take from AHA and post it on AHA.
I gotta say it's not going to be a mind blowing experience to read this article, but it's relevant.

-OCD
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: denny on December 15, 2009, 06:29:32 PM
Denny,
Can I just scan it and post it? Can't see how it violates copyright if I take from AHA and post it on AHA.
I gotta say it's not going to be a mind blowing experience to read this article, but it's relevant.

-OCD

Go ahead....if I hear there's a problem, we'll deal with it then.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: beerocd on December 15, 2009, 10:20:09 PM
OK, there's gonna be some errors - just pretend a drunk guy posted it and use your imagination wherever you see a creative word that you've never heard before. I tried to clean up the OCR scan as well as I can. There may still be some interesting words along the way. If you PM me something that totally doesn't make sense I can go back and compare against the article to fix it.

Vol 27 No. 6 November/December 2004
The Iowa Beer Tinkerers
_________________________________________________________________________________________________
Have you ever wondered, while enjoying a homebrew, how different the beer would taste if you could change just one ingredient in the recipe? This kind of mind- set stokes the natural curiosity of many homebrewers. Some experienced home- brewers possess a vivid “taste for the imagined,” such that they can be induced to drool when asked about their next recipe. This is similar, I suppose, to the bliss felt by Pavlov’s dogs.

To hone this taste, many brewers tinker with a favorite recipe, returning again and again to brew the same beer with minor modifications. For an ideal comparison, a brewer should change only one ingredient at a time. Any difference in the beer can then be attributed to the substitution in the recipe.

Or can it?
Unfortunately, natural variability exists in crops from year to year and from place to place. In fact, the amount of alpha acids found in hops harvested from a single plant can vary by several percentage points between two different years. This leads to a perplexing question: is the noticed change in a beer due to the controlled change in the recipe or a natural variation in the grain. hops or extract?

Another factor that confounds comparisons between “tinkered” beers is that taste comparisons are often made between two beers of different ages. Comparing a relatively green one-month youngster to a detect able four-month old-timer gives the aged beer a monster advantage. To get around this conundrum, some meticulous brewers keep detailed notes so they can compare a “beer in hand” to a “beer on paper.” More often, however, such notes are not available and a brewer will compare a beer in hand to a beer that resides in the cushy recesses of fond memories. With aging differences and natural variations in the ingredients working against a brewer, it’s important to take the lessons learned with a grain of salt (which, ideally, is found on a pretzel).

One way to avoid these confounding influences is to brew 10 batches of beer, all in the same day, using ingredients that came from the same harvest. What a busy brew day that would be. Another way is for a group of brewers to cooperate. Each brewer could make one batch of beer and compare it to the nine other batches made by the other brewers. This is exactly the arrangement set up by a group of brewers in Iowa in late

Two friends discussed the idea and cont acted their homebrewing buddies to see if others would be interested. This kind of proj ect had been on the mind of everyone cont acted, At an initial meeting, the brewers chose a style and formulated the standard recipe. Distinct beer styles characterized by a particular potent flavor (such as IPA or rauchbier) were excluded, because subtle flavor differences in the experimental beers might be hidden under the distinct style. On the other hand, recipes for nondescript beer were undesirable, because we were making 50 gallons of the stuff. The beer would need to be pleasant to consume in its own right. Finally, because all-grain and lagering were not an option for some brewers, we decided to brew a simple porter from extract and specialty grains.


With the standard recipe defined, we moved on to discuss how the recipe could be changed. Dozens of variables were considered and each brewer provided unique insights as to possible effects each variable could have on the final product (see Table 2). In the end, the list of interesting variables exceeded the number of brewers involved in the project. Different variables inspired different brewers and, because there was no duplication of interest, each brewer was able to test the variable he or she found most interesting (see Table 3). As a last order of business, a firm schedule of activities was agreed upon, a detailed protocol was outlined (see Supplement 1) and bulk supplies were ordered.

On a cold November evening, we divvied up the grains, hop pellets and bulk extract and drew our brew water from the appropriate sources. Brew day was just a couple of days later and bottling day couldn’t come soon enough. Busy holiday schedules kept us from meeting to compare the beers until mid-February. Upon tasting, we were pleased
to discover that the beer had aged quite well during the two months since bottling.

The resuIts
By itself, the beer tasted pleasant, but plain. While sweet, it would have benefited from additional malt and a stronger hop profile. The steeped chocolate malt provided an interesting nutty hint that saved the beer from being completely artless. For the purpose of the experiment, the beer completely fulfilled our designs. The flavor was simple enough on the palate that subtle flavor
differences would be detected, but was interesting enough for the brewers to desire to consume the beers. The color was a bit tamer than we would have liked. The beer was too light for a porter and would be better classified as a brown ale. Unless otherwise stated, the physical characteristics such as head and color of the beers were identical to the characteristics of Standard A.
         Sweet Porter Recipe
         3.3 lb (1.5 kg) Munton Dark Malt Extract
         3.3 lb (1.5 kg) Munton Amber Malt Extract
         0.5 lb (227 g) Chocolate Malt
         2.0 oz (56 g) Fuggles hops, 4.4% alpha acid,
         60 mm
         0.5 01(14 g) Tetnanger hops, 4.0% alpha acid, 5 mm
         I tsp. Irish Moss
         White Labs Ready to Pitch Burton Ale Yeast 5 gal Iowa City well water
         0.75 cup corn sugar (to prime)
         Desired 06: 1.045
         Actual 06: varied greatly, from 1.048
         
Standard
The beer poured a one-finger head, which lapsed to a ring around the edges by the end of the glass. A few bubble streams raced to the surface and cloudiness was glaringly evident in the brown liquid. The scent was sweet with the flat grassy hop tone that can come with Fuggles.
Sweet malt predominated the palate to start. Darker grains then appeared in the form of mild hazelnut and a gentle grain bitter that quickly blended into a grassy hop finish. Once down the throat, the tongue quickly lost all memory of the beer, including the light to medium-light body.
All in all, it was a pleasant beer probably tasted during its prime. It was safe, not unique, the kind of beer used to turn a commercial beer drinker onto homebrew.

Variations
6.5-gallon ferment (instead of 5-gall on ferment): The recipe used to make this beer was identical to the recipe used to make Standard A. The beer was fermented in a 6.5- gallon carboy in order to retain the krausen in the fermenter, whereas Standard A was fermented in a 5-gallon carboy and lost about a quart of krausen out of the blow-off tube.
When consumed alone, the 6.5-gallon fermented beer was a satisfactory home- brew. A bitter bite at the end of each sip left a memory of the beverage in a way that Standard A lacked. When compared side by side with Standard A, however, the bitter bite made the 6.5-gallon fermented beer distinctly less desirable. Delightful fruity flavors tasted in Standard A were overwhelmed by an astringency that conflicted with the sweet malt and disarmed any nuttiness that may have been present. The grassy hop finish took on a sharp edge that made some tasters wonder if dandelions had grown on their tongues.
Despite the weak finish to Standard A, the tasters unanimously preferred the delicate play of flavors found in Standard A over the bitter punch of the 6.5-gallon fermented beer.
Irish Ale Yeast WLPOO4 (instead of Burton Ale Yeast WLPO23): The physical characteristics were identical to Standard A and the flavor was very similar. The sweet malt was a bit softer than Standard A, perhaps because of an interesting hint of silky cream like that found in an oatmeal stout. It wasn’t clear if the beer had a heavier body or if the creamy taste tricked the mouth into that perception.
Cascades (instead of Fuggles):
While the physical characteristics were identical to Standard A, the hops made the beer an entirely different experience. Most notably, this beer was too hoppy to be a porter. The West Coast hop profile changed this beer into an American Brown that was enjoyed by all the tasters. The citrus floral “C” hop profile worked well in the sweet malt, perhaps even standing strong because the gentle beer had been designed to allow subtle flavor differences to be detected.
Kent Goldings (instead of Fuggles):
The physical characteristics were identical to Standard A, but the hop profile dramatic ally changed the character of the beer. While not bitter, there was a refreshing spiciness, a tan’, earthy flavor that worked quite well with the nutty flavor from the chocolate malt. Hop level was appropriate for the sweetness of the beer. Perhaps the most pleasant of the beers tasted that
evening. John Bull (instead of Munton & Fison): Unfortunately, this brew became infected. It turned to sour vinegar in the primary.

Standard B
Standard B was identical to Standard A, except the water came from a different well (the same aquifer, but some 25 miles away). The two beers shared physical characteristics and were indistinguishable by taste.
Variations
Tettnanger (instead of Fuggles):
Physical characteristics were similar to Standard B, but the flavor was quite different. The Tettnanger hops bit earlier and were more pronounced and aromatic than the Fuggles used in Standard B. Hop level was appropriate to the intensity of other flavors and played well with the sweet malt. Additionally, the hop experience pushed the flavor of the beer beyond the swallow, whereas the flavor of Standard B ended abruptly when the beer left the mouth.
Plus Dextrine Malt: As dextrine malt had been suggested to affect the head of the beer, we were disappointed to see no difference in the size or retention of the head when compared to Standard B. The color was barely darker than Standard B, but the flavor of the two beers was indistinguishable.
Standard C
This recipe was identical to Standard A, except the water was obtained from a ‘ell located near the Mississippi River, some 50 miles away. The easily generated head was foamy and enormous, like a bubble bath in a beer glass. About half of the head subsided while the beer was consumed, and only because some of the foam stuck to our lips and tips of our noses.
This beer was lighter in color, lighter in body, had a gentler sweet-malt flavor, and was perhaps a bit hoppier. Upon discuss ion, we discovered that the brewer had diluted this beer in a way that none of the other brewers had. After racking to the secondary, the brewer had topped off the carboy with tap water. While this can’t explain the differences in the head, this dilution may explain the lighter color, body and gentler sweetness. The increased perception of hops may simply be the result of other flavors having been diluted.
Variation
Wyeast British Ale Yeast (instead of Burton Ale Yeast): This beer was identical to Standard C in regards to physical characteristics and flavor, except for a hint of cream that persisted through the quaff. Like Standard C, this beer had also been diluted after racking to secondary.

ConcIusion
Not surprisingly, the flavor of the beer was most dramatically influenced by the hops. Our simple porter was transformed into a German ale by Tettnanger hops, an American brown by Cascade hops and an English ale by Goldings hops. The brewers who chose to use different hops were interested in learning the distinctive qualities of the hops. By comparing the beer, each brewer obtained firsthand experience with the flavor of each hop used. A second experimental beer is being planned and,

in order to further expand our experience base, some brewers will vary the hops.
Size of the fermentation vessel, the variable we considered least likely to affect the flavor of the beer, was actually the second most influential factor. As the two beers were prepared by the same brewer and the two fermentation vessels sat side by side, there can be little doubting the results. Perhaps the urban legend of foul- tasting fusel alcohols being blown out with the krausen is true. We are now interested

Variables tested

in comparing the quality of brew fermented in glass to brew fermented in plastic.
We were surprised that the different yeasts had barely detectable effects on the beers. This may be that the yeasts used in this experiment were chosen because they arc all known to have relatively neutral effects on flavor. More notable differences may have been apparent if our choices of yeast had been bolder.
Perhaps most surprising was that the source of water had no effect on flavor despite having an enormous impact on head and head retention. How could the physical characteristics change so much without having a notable effect on taste? This question will be explored further in our next experimental brew session. Interestingly, we found that dextrine malt did not affect head or head retention, contrary to numerous sources we consulted. It’s possible that dextrine malt needs to be mashed in order to increase head retention.

final Conclusions
For the experienced brewers, some of the changes in the recipe had predictable effects on the beers, a confirmation of their “taste for the imagined.” For newer brewers, this experiment will play a pivotal role in their development of this taste. The unexpected results intrigued new and experienced brewe rs alike. Some brew lore was called into question. What other information, which we assume to be correct, is actually inaccurate? This fresh perspective has encouraged the experienced brewers out of brew ruts and to start thinking outside the box again.

Another rewarding aspect of the experiment was meeting and exchanging ideas with other homebrewers. Each person came to the initial meeting with a different background and a different level of brew experience. The exchange of ideas and opinions was wonderfully engaging and has sparked even more “beer-tinkering” thoughts in our restless minds. I can’t wait for our next experiment.
____________________________________________________________________
Paul Ogg drank macro-swill until a friend finally submitted to his begging and taught him how to brew. His professional actMties include laboratory instruction and research in cancer and virology. By the time this issue is at the press, Paul will have earned his Ph.D. in Molecular Biology from the University of Iowa. Hes eager to begin his post-doctoral position at the University of Colorado, Boulder.



Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: blatz on December 15, 2009, 10:31:11 PM
very interesting stuff - I'd be really interested to hear how babalu's experiment turns out especially.  I make some great pils, but I always get dinged for the bittering being too harsh relative to commercial examples - perhaps this is it?

while Kai pointed out that many german brewers do this, how many american craft brewers do?  Is it a common thing?  I'll ask our local brewer, but am curious what other folks have heard?
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: Kaiser on December 16, 2009, 01:41:30 AM
I plan to do this as my next side-by-side for an Alt. I actually have a pretty strong opinion for removing the Kräusen and wonder if I'm right with that.

Clean non-lingering bitteness is a hallmark of German beers.

I once read an ad in an issue of Brauwelt International where foam control was advertised as limiting the loss of bitterness. Obviously this was targeted at non German brewers since foam control is not allowed in German brewing. 

Kai
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: bluesman on December 16, 2009, 02:45:40 AM
I plan to do this as my next side-by-side for an Alt. I actually have a pretty strong opinion for removing the Kräusen and wonder if I'm right with that.

Clean non-lingering bitteness is a hallmark of German beers.

I once read an ad in an issue of Brauwelt International where foam control was advertised as limiting the loss of bitterness. Obviously this was targeted at non German brewers since foam control is not allowed in German brewing.  

Kai

May be...but I have found through blind tastings a clear distinction between Authentic German beer and American examples of German style beers in the hop character and hop flavor profile...particularly in the fest beer examples.

There seems to be a refined bitterness and a spicy flavor attributed to the German style fest beers as opposed to a more pronounced bitterness but yet cleaner hop flavor profile attributed with American examples of German Fest beer.

I really believe the clean but yet spicy hoppiness in German beers is primarily attributed to the regionally grown German hops that are used ...Hallertau Hersbrucker, Spalt, Tettnager and Saaz as opposed to the American grown examples of German seed hops.

The following link outlines the real differences in the regionally grown hops and how they affect the bitterness and flavor of beer.

The alpha-acids content of the German variety Perle, for example, is 3-4% higher in Oregon than in Bavaria where the hop was developed. The U.S.-bred Nugget regularly has alpha-acids levels of 11-15% by weight in Oregon and Washington but only 10-12% in Germany, despite good cone production in both locations. Cascade, selected in Oregon, generally contains more alpha than beta acids when grown in Oregon but slightly more beta than alpha acids when grown in the Yakima Valley of Washington. Although the total level of alpha acids may fluctuate somewhat between seasons and locations, the alpha-acids composition of most varieties, as indicated by the relative proportion of major alpha-acids components such as humulone and cohumulone, changes relatively little, regardless of area of production or season .

http://brewingtechniques.com/library/backissues/issue1.1/haunold.html

Kai...I am interested to learn the findings of your Krausening experiment.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: dhacker on December 16, 2009, 01:18:04 PM
Thanks OCD for posting it and Denny for allowing it. I'd be surprised if a lot of people don't at least give it a try. I know I will.

6.5 gallon carboys could become an endangered species!  :D
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: blatz on December 16, 2009, 02:32:50 PM
6.5 gallon carboys could become an endangered species!  :D

I would think that buckets are much more useful to removing the braun hefe than hoping the krausen is pushed out, no?
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: denny on December 16, 2009, 04:40:47 PM
while Kai pointed out that many german brewers do this, how many american craft brewers do?  Is it a common thing?  I'll ask our local brewer, but am curious what other folks have heard?

None that I'm aware of.  Which is not to say none at all, but I've never seen or heard of it being done with the craft brewers I know.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: Thirsty_Monk on December 16, 2009, 06:11:55 PM
I visited multiple Czech breweries.
They use open tubs (like Anchor Steam) to do primary ferment.
I do not think that they remove the krausen.
As a matter of fact they had their own lingo as far as krausen stage was concern.
Czech Pilsner has "firm" bitterns but there is not harsh bitterns to it.

I think hop additions (FWH, 85min, 60min, 20min ...) has more to do with harsh bitterness (of course hop variety).
There are brewers who like late hopping with more hops to reduce this harsh bitterness.
Jamil Evil Twin is prime example.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: dhacker on December 16, 2009, 06:35:21 PM
6.5 gallon carboys could become an endangered species!  :D

I would think that buckets are much more useful to removing the braun hefe than hoping the krausen is pushed out, no?

Perhaps . . but according to Ogg's article, they used carboys. Either way should work to some degree.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: Kaiser on December 16, 2009, 08:16:33 PM
I visited multiple Czech breweries.
They use open tubs (like Anchor Steam) to do primary ferment.
I do not think that they remove the krausen. 

they may not remove the Kräusen but they also tranfer the beer to the lagering tanks before it is completely done fermenting and the Kräusen falls.

At the AB brewery that I visited the gunk sticks to the top of the fermenter.

Kai
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: Thirsty_Monk on December 16, 2009, 08:28:45 PM
I visited multiple Czech breweries.
They use open tubs (like Anchor Steam) to do primary ferment.
I do not think that they remove the krausen. 

they may not remove the Kräusen but they also tranfer the beer to the lagering tanks before it is completely done fermenting and the Kräusen falls.

At the AB brewery that I visited the gunk sticks to the top of the fermenter.

Kai
They transfer to the cellar when they are 75% done with fermentation.
I did not see this but would not almost all the krausen be down?

I see another reason to start fermenting in SS sink :)
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: beerocd on December 16, 2009, 10:26:08 PM
6.5 gallon carboys could become an endangered species!  :D

5 gallon batches may become a thing of the past. ;)
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: dhacker on December 17, 2009, 03:22:41 AM
 :D :D
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: blatz on December 18, 2009, 03:13:44 PM
I was thinking about this thread at about 7am this morning when I was doing the second blowoff jar exchange this week from my Old Ale (that ironically was overfilled *yes*, no conical this time  :D )

If you purposefully overfill a carboy to induce blowoff, won't the yeast loss potentially be detrimental?  Judging by the slurry I have dumped out of the blowoff jars on this old ale, I've lost at least a cup to 1.5 cups of medium density slurry. 

That's why I wonder if a bucket or conical where you can just skim the braun hefe off is a better vehicle for this practice? 
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: ndcube on December 18, 2009, 03:19:00 PM
I wonder if you had a piece of plastic with holes drilled in it suspended above the beer if it would provide more surface area for the bittering substance to cling to rather than just the sidewalls.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: beerocd on December 18, 2009, 03:30:13 PM
Judging by the slurry I have dumped out of the blowoff jars on this old ale, I've lost at least a cup to 1.5 cups of medium density slurry. 

Why aren't you keeping the yeast for future batches?
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: blatz on December 18, 2009, 03:36:43 PM
Judging by the slurry I have dumped out of the blowoff jars on this old ale, I've lost at least a cup to 1.5 cups of medium density slurry.  

Why aren't you keeping the yeast for future batches?

I would but I don't know how to do that and still be sanitary.  

FWIW - I rarely use carboys at all anymore, and when I do its for big beers where if I don't save the yeast, but I still would like to learn your process.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: Kaiser on December 18, 2009, 04:44:33 PM
If you purposefully overfill a carboy to induce blowoff, won't the yeast loss potentially be detrimental?  Judging by the slurry I have dumped out of the blowoff jars on this old ale, I've lost at least a cup to 1.5 cups of medium density slurry. 

I have been wondering about this as well: How much does the yeast in the Kraeusen contribute to the attenuation of the beer later? Is there enough yeast in the beer to finish the job or does it need some of the yeast to fall back and help out.

What I have read about the brewing of Weissbier indicated that the yeast should not fall back and should be removed but this summer I made a Weissbier where I blew off the yeast and the fermentation slowed down significantly after going string and having  reached about 1.035. I’m not sure of that had anything to do with the blown off yeast.

Kai
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: dhacker on December 19, 2009, 01:45:49 AM
Is it just the braun hefe that has the propensity for sticking /clinging to whatever it contacts? If so, and yeast loss is a concern, why not an appropriately long, sanitized length of tubing, big enough in diameter to be "bunged" into the carboy neck, stretched vertically with some sort of airlock at the end making a braun hefe collecting chimney of sorts? The braun stuff sticks, and the desirable yeast fall back into the fermenter.

I did this a number of years ago . . Kind of a cheesy Burton Union when I was gonna have an explosion. I drilled some holes in the bucket's bottom, sanitized them, pushed the stoppers and airlocks in, and pinned them to the carboy. Worked pretty well for a panic fix!  ;)

(http://i1013.photobucket.com/albums/af255/dhacker50/EC1-1.jpg)

(http://i1013.photobucket.com/albums/af255/dhacker50/EC2.jpg)
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: dhacker on December 19, 2009, 02:20:54 AM
Stumbled across this as I was doing some more perusing. Nice history on British brewery practices of old . . .

http://zythophile.wordpress.com/2008/09/24/a-tasty-drop-the-history-of-an-almost-vanished-fermentation-system/
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: denny on December 19, 2009, 04:13:35 PM
I have been wondering about this as well: How much does the yeast in the Kraeusen contribute to the attenuation of the beer later? Is there enough yeast in the beer to finish the job or does it need some of the yeast to fall back and help out.

Being the pragmatic type, let me answer this question with a question....have you ever had trouble getting a beer to attenuate after it has had a blowoff?  I know I haven't had any trouble that could be directly related to blowoff.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: Kaiser on January 30, 2010, 05:25:10 AM
I gave the two batches, which I dedicated to this topic, a quick taste tonight. It is an Alt and still rather cloudy after 4 and 2 weeks at 4 C. But judging from samples under the microscope it seems to be chill haze. So I added gelatin to both.

But I tastes the hydrometer samples and I'm convinced that the batch where I allowed the Kraeusen to fall back in the beer has a harsher and more lingering finish than the batch where I skimmed the Kraeusen. The difference is not very prominent though.

Unfortunately the Alt did not come out as expected. Attenuation is rather poor due to the Munich malt I used. I used Franco Belges and this is likely the last time I use this malt. In addition to that I also used Hallertau Tradition since I have a lot of those and they must have lost quite a bit of alpha acid. But I don't think that this will invalidate the experiment.

I'll have a better idea once the beer is on tap.

Kai
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: denny on January 30, 2010, 04:46:52 PM
Kai, did you do this as a blind tasting?  I look forward to the results of that kind of test.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: dhacker on January 31, 2010, 12:07:43 AM
Denny . . I know you are pragmatic!  ;) (Maybe I an too . .)  

So, let me ask a question in response to your question . . Is it not possible to make an objective judgement of flavor without doing a blind test?

 
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: MDixon on January 31, 2010, 02:37:47 AM
Attenuation is rather poor due to the Munich malt I used. I used Franco Belges and this is likely the last time I use this malt.

This seems like and odd statement from you. A single usage and you discount this at the issue?

I don't have in my inventory who my base Munich malt is from, but I suspect it may be MFB and if so have never had an issue with it.
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: Kaiser on January 31, 2010, 03:23:15 AM
Kai, did you do this as a blind tasting?  I look forward to the results of that kind of test.

I did 3 sets of two and was able to get the first one right. On the second one I noticed that the lingering bitterness is not easily erased by the next beer which does make distinction on this characteristic difficult.

I also didn't draw enough beer for large enough samples for more thorough tasting.

Kai
Title: Re: Blowoff tube vs. airlock. Does it affect bitterness?
Post by: denny on January 31, 2010, 04:42:48 PM
Denny . . I know you are pragmatic!  ;) (Maybe I an too . .)  

So, let me ask a question in response to your question . . Is it not possible to make an objective judgement of flavor without doing a blind test?

 

Maybe, but my experience is that as long as you know which beer is which, you will always have a bias on a subconscious level.  For instance, in my FWH experiment, when I poured the 2 different beers for myself, I was sure that I could tell which was which and what the attributes were.  When my wife poured 2 of one and one of the other, it took me 3 tries to pick out the different one, and even then I was wrong about which one it was!