Make your own free website on





I know, I know. DECOCTION MASHING? What the heck is this? Even Tech Guy starts to sniff when anyone suggests anything more complicated than good old reliable single temperature infusion mashing. But when JUDGE Tech Guy evaluates styles calling for malt flavor and aroma, and gets nothing but hops, he suggests that perhaps a modification of mashing technique is in order. So listen up. If you really want to add malt flavor and aroma to your beers, you gotta try Decoction Mashing.

WARNING: If you don't grain brew, skip this tip. It's REALLY scary, and you will never want to even think about grain brewing. So look at a different page. I mean it. Right now. Get outta here. Beat it. Scram.

Take off. Your Mom's calling you.

Ok. Traditional German brewers didn't have highly modified malts to work with. Frank Zappa being the Mother of Invention, they had to figure out a way to get full starch conversion. The only way they could do that was to raise the temperature of their mashes, taking the malt through each of the optimal enzyme temperature ranges. They didn't have steam-jacketed equipment, and in fact were using firewood to heat water for brewing. Adding boiling water to the mash led to thin mashes, and thus poor conversion, hazy bier, and lousy shelf life. So, some

enterprising fellow said:

"Liszen up, you schweinhunds! If ve remove zome of zis mash, und raize ze temperature through ze converzion rangez to a boil, zen return it to ze mash, ve vill get ze dezired rezult!"

The desired result (full starch conversion) brought with it some unexpected benefits, namely full flavored, malty beers. Think about Bock/Doppelbock. Think about Vienna and Maerzen/Oktoberfest. Ditto all the other German Biers. Like Weizen. Malty aroma, malty flavor.


First, the very basic theory. Decoction means "To extract by boiling."

If you think in terms of the Centigrade thermometer, the numbers are easy. Protein rest occurs at 50&degC (122&degF). Saccharification rest occurs at 60&degC (140&degF). Dextrinization rest occurs at70&degC (158&degF). Thus, you are looking for a 50-60-70&degC series of mash temperatures.

The Protein Rest is essential when the malt is poorly modified, and serves to decompose heavy, gummy, insufficiently modified malt particles. The stability of beer is largely established during this rest. When using well modified American 2-Row malts, the Protein Rest is probably unnecessary.

The Saccharification Rest is where Beta-amylase enzymes break starch into sugars. At 60&degC, Beta-amylase breaks glucose molecules from the ends of starch chains, then rejoins them in pairs with a water molecule to create maltose. Beta-amylase can only go so far as the "B-limit dextrin." (The B-limit dextrin is the one that gives the intense blue reaction with iodine.)

In the Dextrinization Rest, Alpha-amylase splits soluble starch into smaller fractions, including glucose, maltose, maltotriose and dextrins. It can only go so far as the "A-limit dextrin." The glucose and maltose

production is nominal. Primary sugars formed during this rest are unfermentable, but will leave a rich sweetness in the finished beer.

The Final Decoction involves boiling about 40% of the liquid part of the mash for 20 minutes and very slowly returning it to the main mash. The boil itself deactivates (kills) the enzymes in the liquid, and then raises the temperature of the main mash out of the enzymes' active temperature range, thus stopping conversion. Care should be taken to not raise the temperature of the main mash above 75&degC (167&degF), because this could cause unconverted starch particles to burst, with no enzymes left to convert them. It also serves to further put sugars into solution for sparging. Finally, the last mixing of the mash will permit it to settle slowly and to form a well-stratified filter bed.

A few other things happen in decoction mashing, besides starch conversion. During boiling, sugars and amino acids combine (Maillard reactions), producing brown colored pigments called melanoidins. These compounds darken the beer, and produce the great flavor and aroma of the malt. You may get the color, but you won't get these flavors and aromas from Crystal, or Chocolate or CaraPils malt in an infusion mash. But if you use those malts in your decoction mash....Ka-zowie! Those are full of melanoidins already, and decoction mashing will further intensify their flavors and aromas.

Additionally, when raising the temperature of thedecoction, particles of unconverted starch are burst and absorbed into the liquid at temperatures above 75&degC (167&degF). This makes them accessible to enzyme activity when they are returned to the main mash. Thisotherwise lost extract increases both the quality and quantity of the extract yield. In other words, you should see higher starting gravities from the same amount of grain than you would get from an infusion mash.

Now the procedure. Heat your strike water to the temperature where your mash will come to rest at the first desired temperature. (Whether you want a protein rest is up to you. If not, shoot for a 1st rest at 60 C.) Mash in as usual, and allow to rest for 15 minutes. Ready to decoct? Using a strainer, scoop out about 30% of the grain, leaving the liquid behind, and cover the mash vessel. (The liquid contains most of the enzymes, and decoction will kill them. It's OK to take some liquid, but try to get mostly grain.) Put the decoction grain into another kettle, and add just enough water to show liquid near the top of the grain. Heat the decoction, stirring regularly, and raise the temperature of the decoction slowly to the next rest temperature. Remember: "An unwatched decoction always scorches." The temperature of the decoction should increase no more than 1’C per minute. Hold the decoction at the next rest for 15 minutes. Then again raise the temperature of the decoction to the next rest and hold for 15 minutes. Finally bring the decoction to a boil, and boil for 20 to 40 minutes; with the darker beers boil longer than the lighter ones. Stir frequently, and add small amounts of water as necessary to keep the decoction from scorching.

Add the decoction carefully back into the main mash by degrees. You will have to stir like crazy to keep from scalding the main mash. You want to raise the temperature of the main mash evenly, and you should stop adding the decoction when you reach your next rest temperature. If you have any decoction left, force cool it to the rest temperature, and add back in to the main mash. Let the main mash rest for 20 minutes, then pull off the next decoction, and repeat the process, until the main mash has gone through the Dextrinization rest. Then perform the final decoction. Sparge and brew as usual.

Question: Whaddya mean "boil the grains," Tech Guy??? Doesn't that leach harsh, astringent tannins into the beer??

Answer: No, Billy, it won't. The pH of thedecoction is acidic enough that the tannins won't fall out of the husks. The only real time you should concern yourself with boiling grains is when the pH of the decoction is above 5.5, which it shouldn't be in a proper mash. If you are worried, get some pH papers and test your mash during the 1st 15 minutes of the rest.

Question: But Tech Guy, this sounds hard. Is it really worth it?

Answer: Yes. It's harder to describe than it is to do. We're talking World Class beers here. Next question.


Question: But Tech Guy, it takes a long time to do all this stuff. there an easier way?

Answer: Yes. You can do a single decoction by starting with a mash in at 60&degC. Then pull about 40% of the mash out, raise to 70&degC for 15 minutes, then boil for 30 minutes, and recombine with the main mash, to a temperature of about 70&degC (158&degF), followed by the final decoction. Sparge and brew as usual.

Question: But Tech Guy....

Answer: Enough buts. The ends justify the means. Now quit your whining and get brewing.


First Timers:

Kettle Mashing

****** Note: There were some REAL controversial procedures taking place in the original article, involving boiling the whole mash! I have edited Dave's brewing process to a more conventional technique. If anyone is interested in his original Mashing Procedure, copies can be reproduced.

~Mike WInslow

I have been kettle mashing for some time and have come up with a good method that eliminates the tedium usually involved with the simpler mashing systems. You don't need expensive equipment to make good beer -the benefit of expensive equipment is a more controlled process that hopefully involves less labor.

Keep in mind that the more equipment that you use, the more items you have to clean, maintain, and store. Complex brewing setups often contain hard-to-clean areas that threaten the quality of your beer - even mashing is subject to infections, according to Noonan.

When the only equipment involved is a plastic bucket, a slotted copper manifold, and a stainless steel brew pot, the complex process of all grain brewing is greatly simplified allowing the brewer to concentrate on details that make better beer instead of the usual barrage of mechanical details and refinements.

Kettle mashing can produce beer of equal quality to any other method of mashing when one is willing to adapt to it - as opposed to insist in that the method adapt to one's particular brewing ideology and style.

The often repeated concern that kettle mashing is labor intensive is not necessarily true when properly implemented. While it is not an automated process that allows one to flip a switch and come back 3 hours later to cast the yeast, it does not require your constant attention either. I usually check in on the process every 15 or 20 minutes while doing something more entertaining in the meantime.

The key to kettle mashing is a proper manifold that will fit into your brew pot and allow it to act as a mash and lauter tun. I use a device made from half inch copper pipe that is conceptually a racking cane attached to a slotted octagon manifold. This device fits into the brew pot and the racking cane portion allows the wort to be siphoned from the grain bed. I chose this device over the more common false bottom/drain valve arrangement because I don't like to mess up a good brew pot with shutoff valve appendages.

To kettle mash, start with 2 gallons of hot water and add grain and additional water as needed. The goal is to create a mash that is as stiff as practical yet can be easily stirred (No less than 1 qt. per lb. of Grain. MW). The ideal mash will have perhaps a half inch of liquid on top of the grain when you let it settle.

Put the brew pot on the stove and heat it to 152F, stirring frequently so as not to scorch the kettle. Then let the mash rest for an hour, stirring occasionally. If the temperature drops more than a couple of degrees, apply heat as needed.

After an hour or so, insert the manifold, start the siphon (careful not to burn your mouth) and drain the wort into the plastic bucket. Depending on your malted grain, you may want to restrict the flow sothat the suction does not cause the grain bed to compress. When the liquid begins to flow crystal clear, dump the cloudy wort back into the brew pot so that the final liquid you collect is clear.

While it is draining, go do something more interesting. After all theliquid has drained from the brew pot, add 170F water to the grain so that it can be easily stirred. (Subtract your first runnings amount from your total pitching amount and add that volume to the kettle; i.e. Total Volume 5.5 - 6 Gals, subtracted by your run off (2.5 Gals) = 3 - 3.5 Gals. MW) Allow to rest for 15 -20 minutes. Restart the siphon, but recycle the siphoned liquid back to the brew pot until it is brilliantly clear before collecting it in the plastic bucket with the original runnings.

Sparge with additional hot water if necessary.

Now, dump the spent grain from your brew pot, wash it out, dump your fresh wort into it, and put it back on the stove to begin the boiling/hopping process which I won't bother describing..

Dave Hopf