Republished from BrewingTechniques' January/February 1997.

The Use of Raw Barley

A: It's hard to argue with Guinness about anything connected with the making of stout. About the best I can say for my published statements is that they err on the side of caution, which is what I generally try to do when handing out advice to neophyte all-grain brewers.

The brewing textbooks I have consulted agree that barley starch gelatinizes at around 150° F (66° C), compared with 180-190° F (82-88° C) for rice and corn starch. It would seem, then, that plain unmalted barley could be milled and used in a mash without cooking. Furthermore, in Northern Germany some Pilsener brewers evade the spirit-- but not the letter--of the Reinheitsgebot by deliberately making a pale malt that is so undermodified as to be, for all intents and purposes, raw barley. They use this grain in their Pilseners for the same reason Guinness uses barley in its stout: as a "body builder" to increase the palate fullness and foam retention of the beer.

I shy away from advising the use of raw barley for two reasons. First, the quality of raw barley available to home brewers in the United States is highly variable. Much of it is six-row feed barley whose high tannin content and other properties, including poor uniformity of kernel size, make it unsuitable for use in brewing.

That brings us to the problem of millability, if I may coin such a word. Have you ever tried to chew raw barley? The stuff is as hard as BBs. To get a reasonable extract from it, the interior of the grain must be reduced to flour so that it can disperse in the hot mash water; unlike well-modified malt, you can't get away with a coarse crush that merely breaks open the kernel and leaves much of the interior in large pieces (grits). You either need a six-roller mill or you need to first mill the grain coarse, then separate the husks from the grits with a sifter and remill at a tighter, harder-to-crank setting (this is basically what a six-roller mill does).

If you try to get away with a single, tight milling, you will have powdered husks and a tight bed in the lauter tun. In fact, even a six-roller milling will give you a mash that is much tighter than home brewers and most microbrewers are accustomed to. This may be OK for large breweries with motorized rakes that can continuously cut the bed to keep the wort flowing, but for a home or pub brewer, the lautering operation will be tedious to say the least.

I don't know how much trouble you would have with a mash that was, say, 10% fine-milled raw barley and 90% coarse-milled barley malt. It might not be too bad. The only way to find out would be to try it. If you do, write back and let us know how it worked out. But my advice remains the same: Avoid a lot of hazards and pony up for the pregelatinized flakes. On the scale at which we are working, the added cost is not that great.

I might add as a general observation that this question pinpoints the problem with trying to apply brewing lore garnered from the large commercial breweries to our smaller ones--whether home or micro. The "big guys" are quite correct in their brewing science, but their sophisticated equipment is what makes it possible for them to exploit their hard-won knowledge. For them, the payoff is saving significant money on raw materials and labor. But we are in a different situation.

Melanoidins and pH

A: I am surprised by your experience with melanoidins. The general notion is that high mash pH leads to a darker wort, not because of melanoidin formation, but because of the extraction of tannins from the malt husks. That is one of several reasons why the pH of the mash and of the runoff need to be controlled.

As you know, decoction mashing will always give more color than other mashing methods for the same grist or grain bill. But the relationship between melanoidin formation and the pH of the mash in the decoction kettle--if there is such a relationship--is a mystery to me. I have been unable to find anything about it in my brewing science text books. Even Greg Noonan, a noted expert on decoction mashing, tells me he can't recall seeing anything about it in print. This may be unexplored territory.

I would love to see some data from a series of experiments on this. I suggest making three batches of beer using identical recipes, changing only the mash pH in each. pH can be adjusted with various calcium salts (2) to pH of 5.0 (considered the low end of normal), 5.3 (about average), and 5.7 (the high end of normal). Compare the color of the worts collected in the kettle as well as the color of the finished beers. We would be happy to publish the results of any such experiment.

Esters in High-Gravity Beers

A: It sounds like you have an ester problem with your dark, heavy beers. The first thing to try is a different yeast strain. Although Wyeast #2206 is very popular in German breweries, it is well known as an ester producer and for this reason is not favored for high-gravity beers. I have had good success making Bock beers with Weihenstephan 3470. Wyeast sells this strain as #2124 (Bohemian Lager). It gives a wonderful malty aroma.

I doubt that the Durst Munich malt is the source of the aroma you are getting; try changing your yeast strain first. If that doesn't work, however, you could try a different brand of continental Munich malt, such as Weyermann or DeWolf-Cosyns.

If you are referring to George Fix's comments about Munich malt in his book on the Vienna/Marzen/Oktober fest styles (4), I suspect his comments were based on the quality of domestic Munich malts available at that time. From my own brewing experience, I do not think his remarks are applicable to the continental Munich malts that are available today.

Hoses, Pumps, Diacetyl, and Foam

First, because of our nonexistent budget, we use some ancient hosing that collapses on the intake side of the centrifugal pump, causing the beer to flow in a very convoluted and tumultuous manner. Would this result in what winemakers term "bruising" or in any structural damage to the chemical bonds within the beer? Second, can diacetyl levels be affected by mash temperature or time? And third, every time we mash in, a foamlike head appears during the stirring process. What causes this?

A: First, I am sorry to hear about your nonexistent budget, because I would strongly recommend that you replace that hose as soon as possible. I say this for several reasons. I don't think that the agitation will damage the beer in the way you are thinking. I don't think you need to worry about "bruising" the beer. It is likely, however, that the beer is being aerated. But either way, the hose presents another problem. The collapsing hose will form creases on its liner surface--the white rubber layer that actually touches the beer. Those creases will make it much more difficult to clean; they are not much different than scratches. Sooner or later, they will become places for scum to build up and then for bacteria to grow--reason enough to get rid of that hose.

Now, to explain why I think you are aerating your beer, we have to look at what is happening to your centrifugal pump. The pump body has to be filled with beer at all times when it is running. If not, the pump will "cavitate," and when a pump cavitates bad things happen. Any pump has an intake side where it creates suction, and an output side where it creates pressure. Remember also that the boiling point of a liquid depends on the pressure it is under--if the pressure is low enough, room temperature water will boil. So if you restrict the intake side of a pump, that is exactly what can happen--the suction created by the pump can lower the pressure inside it enough to the point that the liquid boils. When a centrifugal pump cavitates, the liquid inside it is boiling. The machine is trying to move a gas (water vapor) instead of a liquid. That is not what it is designed to do, so the poor thing chatters and howls in protest. Cavitation will quickly ruin the mechanical seal of the pump, and eventually the vibration will wreck the bearings of the pump motor as well. The bearings are very difficult to replace, but they are not the biggest problem. The biggest problem is the mechanical seal.

A pump with a bad mechanical seal will leak, but remember, leaks can go both ways. Instead of liquid leaking out, you may have air leaking in. So the next time you pump beer using your collapsed intake hose, take a look at the centrifugal pump. If you don't see dripping, you can be pretty sure the pump is aerating the beer. In any case, you have two items to take care of. First, replace the hose that is causing the problem. Second, replace the mechanical seal in your centrifugal pump.

I know brewer's hose is expensive, but compare it to the cost of dumping even one bad batch of beer. A cost-effective replacement would be spiral-reinforced transparent food-grade PVC hose, which is somewhat less expensive than regular brewer's hose. It can be cleaned at temperatures up to 150° F (66° C) using strong caustic solutions. (Check the McMaster-Carr [Chicago, Illinois] catalog no. 5544K12 for hose with a 1-in. inside diameter.) I like using it for the intake hose of our diatomaceous earth filter, which has a two-stage centrifugal pump capable of developing 90 psi of pressure and, of course, comparable suction. Some brewer's hoses--even when new--will collapse under the suction of these high-powered filter pumps. The only hassle with the spiral-reinforced hose is that the band clamps that hold the hose ends in place are difficult to tighten.

As to your second question on diacetyl formation: I don't think there is any relationship between mashing schedules and diacetyl. As I understand it, diacetyl originates from pyruvic acid and acetaldehyde, which are both intermediate compounds formed by yeast during the aerobic phase of its fermentation cycle (5). The yeast combine the two into alpha-acetolactate, which then is expelled or leaked out of the yeast cell and oxidized into diacetyl.

There may be an indirect relationship between diacetyl formation and mashing in that worts with low levels of valine (an amino acid) tend to lead to high levels of diacetyl, but, frankly, with well-modified modern malts, even worts created by single-infusion mashing have plenty of amino acids, including valine. The only way to get such low valine levels is to alter the beer recipe by substituting a lot of low-protein adjuncts or sugars for the malt (if this were the source of the problem, it would really be more a matter of grist composition than mashing technique).

Finally, the foam on the surface of your infusion mash: Some of it, I am sure, is air that was carried into the water by the malt husks as the mash was mixed, and then released by stirring. But much of this foam is carbon dioxide, which is the end product of a series of reactions between malt phosphates and calcium ions in the water. This reaction yields calcium salts (which precipitate) and hydrogen ions (which affect acidity).The hydrogen ions then react with bicarbonate (the ion responsible for water alkalinity) to form water and carbon dioxide. The carbon dioxide is not soluble at mash temperatures, so it rises to the surface as foam. The net result of this reaction is a drop in mash pH, which is important for starch conversion. When I see foam on the surface of a freshly mixed mash, I always feel comforted; I know the mash is starting to work.

If, by any chance, you are using the same pump and hose to move your hot mash liquor as your finished beer, then it could be that you are getting a lot of air in your mash from that source (see above). In this case, instead of 1-2 inches of foam on the surface of the freshly mixed mash I would expect to see a thick layer, perhaps 4 inches or more, and I would expect it to diminish once you replace the hose and pump seal.

References

(2) Dave Miller, The Complete Handbook of Home Brewing (Storey Communications, Inc., Pownal, Vermont, 1996).

(3) Charles Papazian, The New Complete Joy of Home Brewing (Avon Books, New York, 1991).

(4) George and Laurie Fix, Vienna, Maerzen, Oktoberfest (Brewers Publications Boulder, Colorado, 1992).

(5) George Fix, Principles of Brewing Science (Brewers Publications, Boulder, Colorado, 1989).