Please note that this is an advanced tutorial and assumes a working knowledge of the Mash Designer (or Complex Mash Schedules in Recipes and Brewing Sessions) and Decoction mashing. If you have not become familiar with the Mash Designer or Complex Schedule type, we strongly recommend starting with the step-by-step tutorial - "Mash Designer - Step By Step Tutorial".

The Mash schedule used in this tutorial is included with ProMash and the filename is "German Mash Double Decoction.msh". You may load it within the Mash Designer to follow along with the tutorial. Please note the amounts and temperatures may be slightly different, depending on your default system settings such as Thermal Mass and Grain Temp.

In this tutorial, we will develop a “Double Decoction” Mash. Here is a graph of what we will develop followed by its steps as seen in the mash designer dialog (or complex mash schedules in recipes and brewing sessions).

Strike and the Protein Rest steps in the above mash (see the Mash Designer Step by Step Tutorial for complete instructions for the infusion and direct heat steps). The First decoction is actually pulled or removed from the main mash during the Protein Rest step. We will start here. In ProMash, the decoction is entered in the step where we use the boiling (or near boiling) decoction to raise the temperature of the main mash, in this example the Low Mash step. Therefore in ProMash we make no changes to accommodate the decoction in the Protein Rest step.

First Decoction Step

In this example we will remove the first decoction at the 60 minute mark in the mash process (see chart below).

We will use the decoction to raise the temperature of the Low Mash step. To provide the time needed to heat and process the decoction we must start or pull the first decoction 95 minutes prior to starting the Low Mash step. This 95 minutes represents the required Decoction Processing Time, Decoction Step Time or Pull Time required and is entered into the Pull Time field of the Mash Designer, of the step the processed decoction will be added to. In this case, the Low Mash Step.

So, we “Pull” the first decoction from the main mash 95 minutes prior to starting the Low Mash step. The decocted mash will be added back to the main mash to raise its temperature from 122F (previous infusion step) to the desired Start Temp for the Low Mash rest of 152F.

The Low Mash will Rest or hold for 65 minutes at a temperature of 152F. We will also enter the Decoction Thickness so that ProMash will properly calculate decoction sizes (see the Mash Designer Step by Step Tutorial regarding the decoction thickness).

Second Decoction Step

In the next example, we will remove the second decoction at the 185 minute mark in the mash process (see chart below).

Again the decoction timing is based on the decoction steps processing or Pull Time. We will use the decoction to raise the temperature of the High Mash step. To provide the time needed to heat and process the decoction we must start or pull the first decoction 40 minutes prior to starting the High Mash step. This 40 minutes represents the required Decoction Processing Time, Decoction Step Time or Pull Time required and is entered into the Pull Time field of the Mash Designer of the step the processed decoction will be added to, in this case the High Mash Step.

So, we “Pull” the second decoction from the main mash 40 minutes prior to starting the High Mash step. The decocted mash will be added back to the main mash to raise its temperature from 152F (previous step) to the desired Start Temp for the High Mash rest of 166F.

All that remains in our example is to add the Sparge step in the same manner as we added the Strike and Protein Rest steps.

Limitations, Notes

Rests Within The Decoction Pull

Frequently the first decoction step contains a saccharification rest of the decoction itself. This is illustrated in the picture below:

However, at this time ProMash does not record or plot multiple steps within the decoction itself, but only accurately calculates the size of the decoction to pull to raise the main mash temperature to the target temperature in the targeted step, along with recording the total time the pulled decoction was removed from the main mash.

Stop Temperatures:

The examples above assume a perfect world for mashing, in that the brewer was able to maintain the start temperatures throughout the length of each rest, and that no temperature loss occurred in the main mash when pulling the decoctions. However, this may not always be the case, depending on your mash system. Knowing the correct stop temperatures (what the temperature is at the end of each rest) can be crucial in properly determining decoction amounts and temperatures. For a discussion on how important the stop temperature can be, please see "Mash Designer, Know Your Stop Temperature".

Decoction Temperatures:

It is important to note that while water has a boiling point of 212 F (at sea level), a decoction pull contains grain as well as water and the boiling point may well be over 212 F. It is important to know where your boiling point for the decoction actually is (if your intention is to bring the pull to a boiling state) to accurately predict decoction amounts needed, and this may take some trial and error. If possible, use a thermometer rated for over 212 F and measure the actual temp of your decoctions, until you know the exact boiling temperature.