This question arises as the result of my recent reading of several different threads on different forums which individually treated the various methods listed in the subject line; I am therefore cross posting this to several homebrew forums.
First, I understand that Dan Listermann has been working on a prototype of a Burton Union for use by homebrewers. I read as much info as I could find about Burton Unions through Google, and as best I can tell -- and someone please correct me if I'm wrong -- the liquid which settles from the krausen is simply recycled back into the beer (I surmise that that would be the krausen that would normally be lost via a blow off tube). One article spoke of recycling the _yeast_ in this way, and the only thing I could figure from that is that some top-fermenting ale yeast is probably carried away with the krausen, but I can't believe that the benefits of this method is simply about yeast, especially if the amount of yeast pitched was adequate. Also, I understand that in using the Burton Union, some of the undesirable nasties in the krausen cling to the equipment and never make it back into the wort; how much of the nasties are eliminated is a question that I will get back to. Anyway, I pretty much look at this method as a way to rescue good beer that would otherwise be wasted when a blow-tube is used, but this method is certainly reputed to do something good for beer flavor or body or whatever -- at least for some types of beer.
Second, there was some recent discussion of the advantages of skimming the krausen, with some gurus feeling that it is definitely beneficial for beer flavor. Now, common sense tells us that skimming can only occur if the primary is done in a bucket or other container with a large enough of an opening for access to skim; however, it also seems to me that when folks ferment 5 gallon batches in a 5-gallon carboy with a blow-tube, "blow-off" of the krausen essentially accomplishes almost the same thing as skimming. Of course, with a bucket you can be sure to remove _all_ of the krausen, whereas with a carboy you will always still have part of it which remains in the headspace. Folks who use the larger 6.5 or 7 gallon carboys for a 5-gallon batch no doubt lose a _lot_ less of the krausen, if any, so in the carboy-world, large versus small carboys is roughly equivalent to skimming or not skimming, at least for volatile fermentations.
Of course, with both carboys and buckets, some of the krausen sticks to the sides and never settles back into the beer; I have read that this helps rid the brew of nasties, but unless there is some particular molecular attraction taking place that would draw the nasties over to the sides where they can stick, I wouldn't think that more than a _very_ small percentage of them end up clinging to the sides, with the rest just settling back down into the beer -- unless they have been blown-off or skimmed.
Third, there has been some discussion about using anti-foaming agents to reduce or eliminate the krausen during fermentation without having any appreciable effect on head retention, and that raises two logical possibilities in my mind: first, that the anti-foam causes some chemical reaction that interferes with foaming (e.g., perhaps reducing surface tension) without actually affecting the stuff that krausen consists of, or second, the anti-foam somehow binds with the stuff that causes or ends up in the krausen. If it is the second, the question then arises whether the bound substances settle out of the beer into the trub, and if so, are just the 'nasties' settling or does some good stuff settle, too. Also, if no krausen forms when anti-foam is used, there will be nothing clinging to the sides of the fermenter, with whatever consequences that has. The chemical effects of anti-foam are apparently temporary, since head retention is supposed to be unaffected; I presume this means that the anti-foam breaks down or is perhaps metabolized by yeast by the time the beer is consumed, or perhaps carbonation reacts with it to neutralize it.
Now, there will always be diverging opinions among folks when it comes to a matter of taste; that will explain why some folks skim and others don't (and not just because they're too lazy to do it). This is perhaps further reinforced by the notion that a Burton Union is tantamount to _NOT_ skimming (unless there is some processing of the krausen before it is returned) and is supposed to be beneficial to beer, while certain gurus insist that skimming _IS_ beneficial. On the other hand, my interest in anti-foaming agents has more to do with advantages other than beer flavor, so long as it is not detrimental to it -- but insofar as flavor goes, if B.U./non-skimming _really_is_ the way to go, and if anti-foam essentially accomplishes the same thing, then it will be an added bonus. Any thoughts about this will be appreciated.
Now I'll conclude with a few questions:
- Is it likely that a Burton Union is better for use with only a limited number of beer styles, such as those ales which were brewed in Burton, rather than an across-the-board application? If so, that might account for why skimming is deemed better, at least for those other styles of beer.
- Does anyone know if anti-foam has essentially the same effect on beer characteristics as a Burton Union? (Sorry, Dan, if I seem to be undermining any future marketing of your device; will it be a 'Phil-Burt' Union? ;-)
I would very much like to see replies from folks who use anti-foam, especially beginning with the boil (I understand from some posts that anti-foam in the boil is effective in preventing boil-overs).
Thanks, and good brewing to all.
Bill Velek