Decoction Mashing Video - Transcript

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This page serves as the script and then later as the transcript for the decoction mashing video.


[Me talking]

Welcome to this instructional video for decoction mashing. This video is not intended to show all the steps necessary for a deoction mashing all grain brewday. Only the the mash itself is shown. We will start at dough-in and end with the start of the lauter.

[show slides of olden day brewers decoction mashing]

The original deoction mash is the triple decoction, which is called Dreimaischverfahren in German brewing. When it was first used it revolutionized brewing. The repeated pulling, boiling and returning of a part of the mash allowed 2 things. The temperature of the protein rest, saccrification rest and mash-out became consistent without the use of a thermometer which brought consistency to the beer without even knowning why this was important. And the repeated boiling of the mash helped to break down the cell walls and therefore make up for insufficient or inconsistent malting of the grain.

[show the triple decoction diagram]

Mash diagram tripple decoction.gif

A triple decoction starts with a dough-in at the acid rest. This rest is held around 35 *C or 97 *F and primarily allows the enzyme phytase to create phytic acid which serves to acidify the mash beyond the acidification that is already happening from a reaction between the water's calcium and magnesium iones and malt's phosphates. This rest also serves to dissolve the malt enzymes into solution and provides a no-rush opportunity for mash pH correction since no significant conversion processes are happening at this temperature.

About a third of the mash is then pulled as decoction and slowly heated to a rest around 70 *C or 158 *F where it is allowed to convert. After that it is brought to a boil and boiled for 10 to 40 min. The shorter times for lighter beers and the longer times for darker beers. After returning to the main mash the main mash rests at 50 *C or 122 *F before another decoction is pulled. When this decoction is returned the main mash will be at saccrification rest temperatures. A final decoction is pulled and boiled to reach mash-out.

As malts became better and more consistently modified, the need for such an intensive and time consuming mashing procedure diminished. As a result of this double and single decoctions masches were introduced.

[Me talking]

Even today's European malts are so well modified that they don't need a decoction mash anymore. But many brewers still use them to impart a more robust flavor to their beers. This flavor which comes from compounds extracted from the husks as well as maillard reactions during the boil is well suited for German Bocks, Dunkels, Maerzen and Bohemian Pilsners. But the long protein rest of the classic triple or double decoction provides a problem when using highly modified malts.

[show enhanced double decoction diagram]

Mash diagram double decoction enhanced.gif

When reading a technical brewing textbook I came across this double decoction which boils as much of the mash as a triple decoction but is shorter and allows for a much shorter protein rest which can also be skipped. I'm now using this exclusively as a replacement for triple decoction mashes. This is also the mash that I will be demonstrating today.

After doughing-in at the acid rest a decoction of about 60 % of the mash is pulled, converted and boiled, After an boil time of 10 - 30 min a part of it is returned to the mash to reach the protein rest while the remainder keeps boiling. Once the protein rest, which can also be skipped is complete, the remainder of the decoction is added to reach the saccrification rest. A second decoction is used to reach mash-out

[show Hochkurz decoction diagram]

Mash diagram double decoction hochkurz.gif

Another double decoction mash that allows for a shortened or skipped protein rest is the Hochkurz mash. In this mash a 2 stage saccrification is used where the decoction is used to move the mash from the Maltose rest to the dextrinization rest. The 2nd decoction is used to reach mash-out. This mashing schedule is still fairly popular in commercial German brewing.

[Me talking]

As mentioned earlier I will be brewing with the enhanced double decoction and for this we need to calculate the size of the 2 decoctions.

[show mash volume equation]

In Palmer's How To Brew book, we find this equation for the mash volume. The recipe uses 4.5 kg (10 lb) of grain and targets a mash thickness of 3.5 l/kg (1.58 qts/lb). According to this formula the mash volume will be 19 l or about the same in qts. This almost as much as will fit into a 5 gal cooler.

[show decoction volume equation ] decoction volume = total mash volume * (target temp - start temp) / (boil temp - start temp)

To calculate the decoction volume we will be using this simplified equation. It is simplified since it does not take into account the different thermal masses of tick and thin decoctions. But since we will be adding a buffer anyway, there is no need to do that. With a starting temperature of 35 C or 97 *F and a target temperature of 66.5 *C the 1st decoction needs to be 9.2 L. To that we add a buffer of 20 % which brings the first decoction to about 11 L. This buffer serves to cover inaccuracies in the equation, temperature loss of the main mash and some evaporation losses in the decoction. For the second decoction, which serves to raise the mash temp from 66.5 C to 76 C we need about 9 L including the 20% buffer.


[show set-up with strike water heating and MLT]

Here are we and almost ready to dough-in.

[show the dough-in process once the strike water temp has been reached]

When douging in below the gelatinization temperature of barley starch, which happens between 64-67 C or 147-153 F, you can dump the water onto the grain w/o the risk of getting dough-balls.

[show measuring temperature]

The temperature has nicely settled to ? *C or ? *F and we will now wait a little and measure pH

[show pH measurement]

I took a sample of the wort in this clean bowl and let it cool down. Measuring cold samples extends the life of the pH meter's probe. The ph is now 5.? . Most of the time however, I don't break out the pH meter anymore since it needs to be calibrated before use. These pH measurement strips

[show ph strips]

are perfectly fine. You can make the package go further if you cut them in half or thirds. Oddly enough, the ones I have seem to be reading 0.3 pH units lower than the actual pH. But once I figured this out I started accounting for it.

[show me with beer]

Now I'll have another beer and be back in 10 min to check on the pH of the mash again and maybe do some adjustments if still necessary.

[back measuring pH]'

Over the last 10 min the pH nicely dropped to 5.?. This is fine for me. During that time the enzymes had a chance to get hydrated and dissolved into the mash water.

pulling decoction

[wide angle, show me pulling the 1st decoction]

In order to pull the first decoction I use a strainer and a large measuring cup. With the strainer I scoop out most of the grain and place it into the pot. Then I add mash water until I reach the desired decoction volume

[close-up, the pot with the grain]

To make measuring the volume easier, I notched my mash paddle every 2 liter to be used with this pot. And now I have the targeted 11 L of decoction. You want to target a decoction mash thickness of about 2 - 2.5 L/kg or 1-1.25 qt/lb. If the mash is to thick, put some of the grain back. Some instructions say that you want the water to barely cover the grain. But I believe that this is way to thick and makes the decoction is difficult to manage while requiring constant stiring to prevent it from scorching.

[close-up, adjusting the flame]

Now to the flame. Keep it low and heat the decoction gently. German breweries target a rise time of about 1 C or 2 F per minute. This is to give various enzymes in the mash a chance to work on the malt. But this malt is well modified and doesn't need that much enzymatic work. That's why I'm fine with going a little faster since I want to be done before dark.

[wide-angle, me and stiring decoction]

While heating you you want to stir the decoction occasionally to even out the temperature. Check the temperature and pay more attention when it comes close to 60 C or 140 F.

[close-up, back stiring the decoction]

While heating the decoction through the starch geletanization range of 60 - 70 *C or 140 to 160 F you will notice a few things. First it starts turning from a milky color to a gooy brown color. This is the starch that is gelatenizing. With time, the mash will get less vicous again. These are the amylase enzymes at work that convert the starch into sugars. That's also why it is called starch liquification.

Now that the mash is somewhere between 70 and 73 *C or 158 and 164 *C I will move it from the burner and wrap it into blankets to keep the rest temperature

[wide angle, pot on card-board and blankets being wrapped around]'

The bottom of the pot can get hot enough to melt synthetic fibers, that's why I either let it cool a little or place a piece of cardboard underneath. The mash is now kept at a high saccrification rest temp until it is completely or almost completely converted. Near the optimimum of the alpha amylase this should only take 15-20 min. Though this rest can be skipped when working with enzymatic strong malts it is a must for mashes with a large percentage of Munich malt in order to get the most out of the enzymes that will not be available anymore after the boil. There is no need to match the saccrification rest temp that the main mash will be held at later since we are just loking for the starch to be broken into smaller dextrines. The bulk of the maltose can be produced later.

[close-up, temperature check and starch test]

We are back now after 15 min to check the temperature and the conversion of the mash. The temperature fell only by ? C which is nice. To check for conversion I found that testing on chalk works best for me. I got that from a techical brewing book and tried it one day with my daughter's sidewalk chalk. Simply apply one drop of mash liquid from the end of the thermometer onto the chalk and add a drop of test solution. You can very nicely see the starch reaction w/o the interference of grain husks or endosperm. This one is not quite there yet, so I'll give it another 5 min.

[wide angle, back to heating the decoction]

The decoction is now sufficiently converted and I'm now heating it to a boil. The heat should be applied gently to prevent scorching and excessive thermal loading of the mash. Target 10 - 20 min to get to a boil. You only need to stir occasionally when the mash starts to bulge up

[close-up, bulging mash being stired]

[close-up, mash nears the boil and hot break starts to form]

Having used only a small pot for this mash I now have to watch out for the boil-over

[close-up, managing break until there is a bubbly boil]

Now that we are past the protein break I will pull a sample of the wort to compare pre and post boil color.

[close-up, taking a sample]

[wide angle, stiring the pot]

Now the decoction is going to boil for a while at a moderate intensity. Stiring should not be necessary though I will give it an occasional stir to make sure that nothing starts to scorch on the bottom of the pot and the mash is boiled evenly. You can also place a lid on the pot to save energy and control the boil-off. Any DMS that is formed in the decoction and trapped by the lid will be boiled off during the boiling of the wort later.

returning decoction

[wide angle, me stirring decoction]

Now that the decoction has been boiling for the last 30 min it's time to return a portion of it to the main mash to hold a protein rest. But before we do that let's check the pH and temperature of the main mash.

[close-up, pot and mash-tun]

Let me first check that the decoction size is still what it was supposed to be or of the boil-off was larger than expected. If it's to little you can add some water after using part of the decoction to reach the protein rest.

You can nicely see the difference in color between the main mash and the decoction. But most of this color difference actually comes from the fact that the main mash still has the milky white color of ungelatinized starch and not from boiling the decoction.

Add a few liters of deoction and mix the mash well. It works best if you keep the thermometer in the mash while you switch between cup and mash paddle with the other hand. Aim for the high temperature of the protein rest which is 55 *C or 133 F. At this temperature the enzymes that create longer chaines proteins are favored. Such proteins are important for mouthfeel and head retention. With most modern malts, including malts from Germany, this rest can easily be skipped dur to their high modification. When you plan to hold a protein rest, do it at the higher and and for a shorter time. A to extensive protein rest with modern malts can lead to a significant degradation of longer chained proteins which results in a loss of head retention and body. That's why I favor this type of decoction mash over the triple decoction since I can keep the protein rest much shorter or even skip it altogether.

[close-up, mash-tun]

Now we hit the 55 C or 133 F protein rest temperature and we will let it rest there for about 10 min. During this time there will already bee some beta amylase activity which will create maltose from the dextrines that were formed in the decoction.

[close-up, pot]

The remaining decoction will keep boiling. It's volume should be sufficient to reach the saccrification rest temperature later. If you think it's going to be to little, add some water and let it come to a boil again.

[wide angle]

Before I return the decoction to the main mash, I'm taking another sample to compare the pre- and post boil colors later.

[close-up, kettle and MLT]

As with reaching the previous rest, the decoction is under stirring slowly added back to the main mash, This ensures that we don't overshoot the target temperature of 67 *C or 153 *F and that the enzymes are not damaged by the hot decoction infusion.

[wide angle]

once the saccrification rest temp has been reached there might still be a little bit of decoction left in the pot. Simply wait until this is cooled down to roughly the temperature of the mash and add it to the main mash. Now that I am able to use the burner for the next 45 min, I can heat my sparge water.

[wide angle, place sparge water onto pot, and drink beer]

Time for more beer. See you in 45 min.

mash-out decoction

[close-up, measuring mash temp and taking a sample for starch test]

Now 45 min later I moved the hot sparge water to a cooler for temporary storage and check the mash for conversion. Looks like we achieved sufficient conversion are are now ready to pull the 2nd decoction.

[wide angle]

Since we don't need to preserve the enzymes or make more starch accessible, this decoction can be pulled thin. I like the idea of simply draining the desired volume of first wort into the kettle. But you can also use a cup to transfer thin mash from the top of the mash into the kettle. This mash will be brought to a boil within 10 to 15 min.

[wide angle, 2nd decoction is boiling, start adding decoction back to mash]

After boiling this mash for 5 to 10 min it is returned to the main mash to achieve a mash-out temperature of about 76 *C or 169 *F. The mash-out serves to stop the beta amylase activity which will basically set the limit of attenuation of the produced wort. Though alpha amylase can also create fermentable sugars, it does that much less efficiently. Alpha amylase activity is still desired during mash out. It is needed to convert any additional starches that have been made accessible during the last decoction and needs to convert any additional starches that are freed during lautering.

[close-up, MLT]

I added the complete decoction at once since the actual mash out temperature doesn't matter as much as the saccrification rest temperature mattered. Here we achieved ?? C or ??? F. Now let's make sure that the starch conversion is complete.

[wide angle]'

Now that the mash is converted and we have reached mash-out it's time to start the lauter. I generally recirculate until the wort runs clear. At this point you are free to use whatever lautering method best suits your need.

[close-up, lautering hose]


[back in the basement]

Let's recap what is necessary for a hassle free decoction procedure:

[show slides]

  • make decoction mashes thin mashes (3 - 4 l/kg or 1.5 - 2 qt/lb) as long as your equipment allows you to.
  • allow for a buffer (10 - 20 % in the size of the decoction)
  • don't make the decoctions to thick
  • heat them gently
  • rest them for conversion
  • return the decoctions in small steps to avoid overshooting the target temp and damaging the enzymes
  • allow any left over decoction to cool and add later
  • check for conversion since enzymes are damaged during this process.

[basement, prost to camera]

Brew-on and Prost.