Republished from BrewingTechniques' November/December 1996.

Hydrogen Peroxide for Sanitation or Aeration

A: To answer your first question: If what you are describing is putting a bottle of hydrogen peroxide (H₂O₂) in the air line between the pump and the aerating stone, then, yes, I think that would work acceptably as a substitute for a sterile air filter. It would probably be more expensive than a filter over the long haul because you would have to use fresh peroxide for every batch.

I am not sure, however, if your peroxide bath would be adequate to deodorize the air. (Air from an aquarium pump has a strong rubber smell that you definitely don't want in your wort.) Most brewers use an activated carbon filter to deodorize the air. You should at least check it out by sniffing the air coming through the stone before using it for the first time. If the peroxide doesn't do the job, an activated carbon filter is not hard to make.

To answer your second question, I consulted my friend Dr. George Fix, author of The Principles of Brewing Science (1). Based on his answer, I would not even try to use peroxide as a substitute for an aerating stone. Here's why.

Hydrogen peroxide is basically a water molecule with a second oxygen atom loosely attached. That loose oxygen is highly reactive and makes peroxide a powerful sanitizer. As you might expect, adding a dose of sanitizer to a freshly pitched wort clashes with the mission of your yeast. When Dr. Fix tried using peroxide to oxygenate wort, he managed to kill most of the yeast rather than make it grow. The resulting fermentation was typically problematic - long lag period, slow and incomplete attenuation, high levels of by-products, and so forth. Based on Dr. Fix's findings, I do not recommend peroxide as a substitute for air or oxygen in cold wort, and I see no point in calculating the volume of H2O2 required.

Lipids and Wort Recirculation Revisited

I am curious about this writer's references. I'd like to figure out which is right: Are lipids foam-negative or foam-positive, and are they "beer-negative" or "beer-positive" in general? You poked a few holes in the author's arguments, but I don't think you fully addressed this lipid issue. It is well known among U.S. home brewers that you are the king of recirculation and long sparges (these are the reasons that you get 34 pts/lb/gal in your homebrew recipes). Because not recirculating seems to go against your basic brewing philosophy, it's not surprising that you would hesitate to entertain the thought of reconsidering this step of the brewing process.

A: Before we get into lipids, let's clear away a couple of misunderstandings. First of all, a long recirculation, as far as I can tell, has nothing to do with extract yield. A long sparge (not outrageously long, but at least 45 minutes and preferably an hour, which is well within the norms of commercial brewery practice) does yield more extract than the very short sparges (half an hour or less) that many home brewers do. A second factor that seems to make a difference is adequate mash rest times. This is especially important to brewers who are using a single-infusion mash and coarsely milled grist. To brewers who use such a regimen, as I do, I strongly recommend at least a one-hour stand in the conversion range (150-156°F [66-69°C]), regardless of what the iodine test may tell you. I have explained my reasoning before (3) and in the interest of space will not repeat that here.

The second misconception is that a vorlauf (recirculation) is part of my basic brewing philosophy. I don't have a brewing philosophy beyond the general precept to make the best beer I can. Anything worth doing is worth doing well. Past that, brewing is not a religion, and I have no interest in turning it into an arcane elaborate ritual. I'd much rather keep it simple. If I recommend certain lengthy and/or troublesome procedures, such as all-grain brewing or using pure yeast cultures, it is only because I am convinced that they will make better beer than a simpler, shorter method. The fact is that I am as lazy as anybody I've ever met and find brewing tedious enough without adding complications to it - unless, of course, those complications improve the final product.

As to those references, unfortunately I cannot retrieve them from the original correspondent at this date. According to Malting and Brewing Science (4), however, the mechanism for the formation of trans-2-nonenal to which I referred has been suggested by a number of brewing scientists and is generally accepted, but it has yet to be conclusively proved in a laboratory. So far the original correspondent is quite correct.

On the other hand, the statement that North American-grown barley has an inadequate amount of lipids is clearly an exaggeration - lower lipid contents than European barleys, yes, but there is a big difference between "less" and "inadequate." If they were inadequate, almost all American breweries - small and large alike - would be having chronic problems. This is not the case, as both my personal contacts and the dearth of attention to this issue in the professional literature attest.

In any case, it is a whale of a jump from saying that a particular mechanism for the formation of a particular staling compound has not been conclusively proved, to saying that therefore there are no known or demonstrable deleterious effects to omitting a certain step in the brewing process. And that is what the argument implied, though my correspondent never said that in so many words.

The basic issue is simply this: Should the brewer make any attempt to clarify the wort before running it off from the lauter tun into the kettle? And if so, how much clarity is required?

My answer is based primarily on my own experience. My first batches of all-grain homebrew were made using primitive lautering equipment. The result was very hazy wort in the kettle and finished beer with what I later learned to identify as typical starchy and astringent/grainy off-flavors.

When you argue about clarifying wort, the first thing to keep in mind is that more than one component of the mash is being carried into the kettle. First, in the case of an infusion mash at least, the mash will always contain some unconverted starch, and clarifying the wort will minimize the amount of starch that finds its way into the kettle and, ultimately, the beer. On this point there is little debate. Except for some extraordinary beers such as lambics, which are made using mixed or wild fermentations, starch is not desirable in wort or beer. It is of no use to brewer's yeast and imparts a starchy off-flavor.

Second, cloudy runoff always contains grain husk fragments. They are particularly prevalent in small brewery mashes because of our simple malt mills. Husks that are carried over into the kettle will be boiled, which extracts tannin from the husks. Again, not much argument in the brewing literature about this. Tannic astringency is not desirable in beer.

So far, we've got two components in cloudy wort that are on the Not Wanted list. If that were the whole story, we would all be trying to make our wort as clear as our finished beer. The case would be as clear as we want that beer to be.

But then there are lipids, which are complex fatty substances derived from the malt. Their case is not as simple. On the one hand, they are widely suspected of being the precursors of some notorious staling compounds (aldehydes, of which trans-2-nonenal is one) that are well known to be the source of undesirable aromas and flavors in old beer. On the other hand, they are also beneficial to yeast nutrition. They seem to be essential for good yeast growth and a healthy fermentation.

Other arguments about lipids remain - for instance, the one you mentioned, about whether they help or hurt foam stability. Various researchers have reported different results. I suspect it depends on which lipids you're talking about. Obviously, the wort for a premium American lager will have a very different lipid profile from the wort for a microbrewed oatmeal stout (to take extreme cases), owing to the differences in grist composition.

The one thing I know for sure is that at least one large American brewery found it got better fermentations by cutting back the vorlauf so as to leave the first runnings slightly hazy rather than "as bright as the finished beer," as one of the brewers put it to me. The brewers attributed the improved fermentation to the higher lipid content of the wort.

Based on all the evidence, including my own experience, I have concluded that clarifying the wort before boiling is a good practice, one that has helped my own beer substantially. I also have to admit, however, that it may be possible for some brewers to clarify their wort too much, to the detriment of fermentation. While I doubt that it's possible for home or microbrewers to clarify their wort as much as the "big guys" can (at least, I know I have never been able to), I can't say so for sure in every case.

So my recommendation is: If you encounter persistent difficulties with fermentation, and those difficulties are not resolved by addressing the usual causes (underpitching, underaerating, and so forth), it is simple to make the experiment of cutting back on the vorlauf to get more lipids into the kettle. But to anyone who is not having problems with yeast nutrition, I say that the benefits of clarifying wort make it well worth the effort. That's what I've found in my own brewing.

References

(2) Dave Miller, "Ask the Troubleshooter," BrewingTechniques 2 (2), pp. 14-16 (March/April 1994).

(3) Dave Miller, Dave Miller's Homebrewing Guide (Storey Communications, Inc., Pownal, Vermont, 1995), p. 106.

(4) J.S. Hough, D.E. Briggs, R. Stevens, and T.W. Young, Eds., Malting and Brewing Science (Chapman & Hall, London, 1982).