Dear Mr. Wizard:

I have a keg of wheat beer that I overcarbonated. When I decant a glass, I get 99 percent foam. I think I know what I did wrong to produce this, but is there anything I can do to salvage this batch?

David Wilhelms
Aberdeen, Washington

Mr. Wizard replies:

I prefer to package beer in kegs for several reasons. Besides being convenient, perhaps the best thing about a keg is that it's very easy to change the carbonation level in a beer. In your case, you either added too much priming sugar or went overboard with your carbon dioxide pressure during the carbonation step. Whatever the reason, the problem can be solved simply by releasing the top pressure on the keg. This method works to drop the carbonation level, but unfortunately, it's not a real sexy technique.

If you drop the head pressure in the keg, it will slowly return as the carbon dioxide in the beer re-equilibrates with the headspace in the keg. If you have a Cornelius keg, make sure the lid re-seals properly, or you could lose a lot more carbon dioxide than planned.

After a few hours, you can hook your gas supply back up to the keg at your normal dispense pressure and check the level of carbonation. You may need to repeat this method a time or two, depending on how badly you over-carbonated your wheat beer! Although this is a nuisance, it is definitely a solvable problem. That's the beauty of kegged beer. If the beer were bottled instead of kegged, then you would be out of luck.

Dear Mr. Wizard:

Help! My last two batches of all-grain beer turned out to be non-alcoholic ... obviously, by mistake! I used a step-infusion method as usual, boiled for an hour and had the prettiest colors, but my specific gravities are less than 1.020. Needless to say, there isn't any sugar for the yeast to feed on. I can't figure it out.

The only difference is that I am cracking the grains a little larger instead of grinding them into smaller pieces. Could this be the problem? Are the moons out of phase? Do I have to make a deal with the devil? Grains aren't that expensive, but it's frustrating enough that I'm considering a return to extract brewing.

Terry Stewart
Highlands Ranch, Colorado

Mr. Wizard replies:

Before you head to a psychic to have your charts done or make any deals you might later regret, here are a few things you should consider. Low yields can be tracked to three general areas: milling, mashing technique and wort separation method. Typically, decoction mashing gives the highest yield, followed by temperature profile and infusion mashing methods. The difference in yield among these mashing styles may be about five percent - really not a huge difference. Wort separation method is also an important consideration, but this is mainly a commercial brewery issue because homebrewers don't have too many options with respect to lauter tun design. This leaves milling.

There is no doubt in my mind that your problem is a direct result of coarse grist. In order for malt starch to be converted to sugar by amylase enzymes, it first needs to dissolve. Generally, most malts have a laboratory extract yield of about 80 percent. This means that, under laboratory conditions, 80 percent of the weight of the malt will end up in the wort as extract. Laboratory conditions are quite different from brewery conditions because wort clarity and ease of wort recovery are not important - the laboratory yield is simply the maximum yield possible. Most systems can easily yield about 90 percent of the laboratory number. This number is most commonly referred to among brewers as the "brewhouse yield."

Using a more finely milled grist can increase brewhouse yield. I like to use the finest grist possible without creating cloudy wort or slowing wort collection. This is simply a matter of gradually reducing the gap on your mill until you get to the point where the grist is too fine and then backing up a step. This is where your problem could get a bit more complicated.
You may have found that the only way to produce clear, easy- flowing wort is by using a very coarse grist. If this is the case, your mill may be chewing up the malt husk or the design of your false bottom may be inadequate.

Experiment by milling samples while using different mill gaps and visually examining the grist. Ideally, you should see chunks of white endosperm (malt starch) and nice, big, fluffy pieces of husk. If you don't see nice pieces of husk you may have an inadequate mill. If that's the case, I suggest finding a homebrew supply store that has a good mill and buying milled malt or, if you like milling your own grain, then you should buy a different mill.

Your mill, however, may not be the problem. If you have a false bottom with large holes or slits, you will be forced to use a very coarse grist to produce a clear wort. Changing your false bottom will address this problem. I have always liked the copper manifold wort collection device that can be assembled in the bottom of a cooler. The width of a hacksaw blade produces a narrow gap that works well with relatively fine grist. This system produces very bright wort, gives a good flow rate and has an excellent brewhouse yield.

I don't think your problem has any supernatural cause and am confident that you will be able to get your yields back on track after making these adjustments.

Dear Mr. Wizard:

Could you please explain Carapils to me? What does this brand-name malt do in a mash, and how does it work? One of my homebrewing pals and I had a recent disagreement about this. He seems to believe Carapils works by leaving behind unconverted starches that the yeast cannot ferment, leading to greater body, mouthfeel and foam stability. I remember reading from various sources that starches are bad in beer, because yeast can't eat them but bacteria can, and so this leads to infections. I believe there should be no starches in finished beer and that starch is not what contributes to improved body, mouthfeel and foam.

Carapils is also called "dextrin malt." I know there are also other "cara" malts, such as cara-Munich, cara-Vienne and carastan. Can you sort out this whole cara-issue? Thanks for your sagely advice, Sir Wizard. It is always much appreciated.

Bill Wible
Philadelphia, Pennsylvania

Mr. Wizard replies:

Caramel, cara or crystal malts are synonymous terms describing a large family of malts that are made by changing the kilning process. All malts are kiln-dried to arrest germination. To make caramel malts, the maltster adds a key step, known as "stewing" or saccharification, before drying. The "stewing" step heats moist, unkilned malt (or re-hydrated kilned malt) to about 158° F. The malt is held at this temperature for 1 to 2 hours with minimal ventilation to minimize drying.

Most caramel malts are made in roasting drums where ventilation and temperature are easily controlled. Stewing allows the starch inside of the malt kernel to convert to sugar, just like mashing. After the stewing step, the malt is then dried and roasted at various temperatures and times.

Caramel malts contain high concentrations of Maillard reaction products ("MRPs"). The Maillard reaction is a complex series of chemical reactions initiated when "reducing sugars" react with free amino nitrogen. This occurs in hot, moist environments. Reducing sugars include sugars like glucose and maltose that are formed when starch is broken down by amylase enzymes. The stewing step drastically increases the concentration of reducing sugars inside of the malt kernel. Free amino nitrogen refers to the nitrogen end of a protein or polypeptide not chemically tied up in a peptide bond (the bond between two amino acids in a protein or polypeptide chain).

The concentration of free amino nitrogen increases when barley is converted to malt. Well-modified malts have a higher concentration of free amino nitrogen (frequently called FAN) than poorly modified malts. When sugars participate in the Maillard reaction they become unfermentable; that's why using a high proportion of crystal malt increases the final gravity of beer.

The Maillard reaction is responsible for the formation of a wide array of aromas including toffee, caramel, toasty, nutty, raisin-like and sherry. The reaction is also responsible for an increase in color.

Toasted bread is a classic example of the Maillard reaction and can be used to illustrate how the reaction can progress from subtle to very pronounced colors and flavors. Some crystal malts are very light in color and flavor and are made using kilning regimens (after stewing) similar to pale malts. Darker crystal malts are kilned at higher temperatures for longer periods of time after stewing. Maillard reaction products are also widely believed to improve mouthfeel as well as beer foam stability.

All the malts you name in your questions are different types of crystal malt. Carapils is produced by Briess in Chilton, Wisconsin and is a very pale crystal malt. Other maltsters make similar products and sometimes use names like dextrin, dextrin or cara-pils to describe their products.

A dextrin is an unfermentable carbohydrate chain that is not large enough to be considered starch because it does not turn iodine black in the iodine reaction. This can be confusing because dextrins don't have much to do with why these malts react the way they do! Cara-Vienne and Cara-Munich are darker in color than these lightly colored caramel malts.

As far as your friendly debate is concerned, you and your pal are both correct! You are correct in saying that starch is unwanted in beer and that caramel malts do not leave starch in the finished beer. And your friend is correct when he says that caramel malts do improve mouthfeel, body and foam stability! I hope this settles your homebrewing disagreement.

Mr. Wizard, BYO's resident expert, is a leading authority in homebrewing whose identity, like the identity of all superheroes, must be kept confidential. To see more of Mr. Wizard, check out the latest issue of Brew Your Own at better homebrew shops and newsstand locations.

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