Hitting the right temperatures for your mash

 

Malt was discussed in a previous post, here we will dive into what to do with the malt to get the most out of it for your brew.  The next step after selecting your malt is to convert its starches into fermentable, and non-fermentable, sugars. That process is called “mashing”. 

There are several methods to the madness of mashing: Single infusion, step infusion, and decoction. Let’s first discuss what the mash is all about. Then we can go into how these methods differ, and why one would be used over another.

What is the reason for mashing in the first place?

• Mashing is the process brewers use to convert starches into fermentable and non-fermentable sugars.
• Enzymes within the grains, developed during malting, are activated at specific temperatures.
• These enzymes break long carbohydrate molecules into shorter sugar molecules. Holding (resting) the wet grains (mash) at temperature promotes this process.

The different mashing methods

• Single infusion
  • Stepping and resting through the different ranges will enhance your brew considerably more than resting at a middle ground. A single infusion mash brings the grist (ground grains) to a temperature ~155/68, where alpha amylase and beta amylase enzymes both can work on the carbohydrate molecules. Single Infusion denatures other enzymes, so their benefits are lost.
• Step infusion
  • By stepping the grist temperature through low to high ranges, specific enzymes are activated.
    • Optional Acid Rest – Dough in a thick mix of grain at 100 ‡ 5 °F (38 ‡ 2 °C) for an optional acid rest of 15 to 30 minutes.
    • Protein Rest – If you start with an acid rest, raise the mash temperature to about 122 °F (50 °C) for a protein rest of about 30 minutes, using a small quantity of hot water and external heat. If you skip the optional acid rest, dough in directly at the protein rest temperature.
    • Beta Saccharification Rest – Increase the mash temperature, using a combination of hot-water infusion and direct heat, to 146 ‡ 2 °F (63 ‡ 1 °C) for a beta saccharification rest of about 15 minutes. Again, you can accomplish this temperature increase by decocting one-third of the main mash.
    • Alpha Saccharification Rest – Next raise the temperature in the same manner to 156 ‡ 2 °F (69 ‡ 1 °C) for an alpha saccharification rest of about 15 minutes.
    • Mash Out – Finally raise the temperature to 170 °F (77 °C) for the mash out and start sparging.
• Decoction Mash
  • Decoction mashing is a traditional mashing technique used in the brewing of certain traditional European beer styles. 
  • It involves removing a portion of the mash, boiling it, and then returning it to the main mash tun to raise the overall temperature. 
  • This process is performed multiple times during the mash to achieve specific temperature steps.
  • Since each step involves boiling a volume of liquid to hit specific temperatures, no thermometers are necessary!
  • Pros and Cons
    • Pros
      • Temperature measurement is replaced by volume measurement
      • More process-driven than time-driven
      • No accidental overshooting of temperatures
      • Undermodified malts are broken up better
      • More intense in time, work and energy
      • Suitable for direct firing with solid fuel
      • Stronger coloration through Maillard reaction
      • More robust beer flavor
      • Greater extraction
      • Specialty malts mostly unnecessary
    • Cons
      • Labor intensive
      • Time intensive
      • Additional equipment required
      • Stronger coloration through Maillard reaction
      • More robust beer flavor
      • Lessens the ability to tune the beer through the use of specialty malts.

Helles Mash Schedule

As we now know, mashing involves steeping grains at a target temperature for a specific period of time to allow enzymes to convert starches to sugars. We saw in the Helles Mash Schedule chart that different enzymes activate and denature at different temperatures. Single infusion mashing aims for the sweet spot where alpha amylase and beta amylase are both sort of active concurrently. Step mashing refines this by progressing through the target ranges for each enzyme we want to utilize. 

One question though – how hot should that water be?

Another look at the Helles Mash Schedule shows how we step through for a 5 gallon batch. The desired temperature is the target. We start with 12 pounds of room temperature grains (72℉) in this example. You should notice that the strike temperature is above the target temperature to start, then boiling at every additional step.

Rest	Desired Temperature	Strike Temperature	Water Volume	Grain Weight
Protein Rest	112	119.6 °F	3.72 gallons	12 lbs
β Saccharification Rest	146	212 ℉	2.2 gallons	12 lbs
α Saccharification Rest	156	212 ℉	1.2 gallons	12 lbs
Mash Out (optional)	170	212 ℉	2.6 gallons	12 lbs

At the end of this process we will have close to 10 gallons of water, The 12 lbs of grain is about 12 quarts or 3 gallons of volume. That’s over 12 gallons of volume! Your mash tun probably isn’t that big. I omit the mash out step and let the boil do the final denaturing of the enzymes. That would give me just under 10 gallons of volume, which my mash tun can handle. Be prepared! (voice of experience here)

Here’s a link to the mash temperature calculator I use. https://www.brewersfriend.com/mash/  This is based on Palmer’s equation for brewing mash, formally known as the mash infusion equation. Since we know the temperature boiling water, the grain weight, the amount of water in the mash at any given step, and the target temperature, we just need to know how much boiling water to add at each step. Easy peasy!

Palmers Equation for Step Mash Conversion Temperatures

The formula is: 

        (T₂−T₁)(0.2G+Wm)
Wa = —————————
        (Tw-T₂)

where

Wa is the infusion water amount,
T₂ is the target temperature,
T₁ is the initial mash temperature,
Wm is the total mash water,
Tw is the infusion water temperature, and
G is the grain weight.

Equation breakdown

Wa: The amount of hot infusion water to add.
T₂: The desired target mash temperature (in °F). Following the Helles schedule: 112°F, 143°F, and 153°F
T₁: The initial temperature of the mash (in °F). This is the ambient temperature of your brewhouse/backyard.
Wm: The total amount of water already in the mash (in quarts).
Tw: The actual temperature of the hot infusion water (in °F). 212°F at sea level.
G: The weight of the grain in the mash (in pounds). This is recipe dependent, include all grains that will be mashed. Do not include any specialty grains that will be only steeped in the brewpot.

So the real variables are the target temperatures and the weight of the grain bill.

How long to steep the grains at each rest?

The idea is to give the enzymes enough time to convert the starches for the results we want to see in our final beverage. As stated before,  the protein rest will break down the proteins in the malt, resulting in a clearer brew. The beta amylase enzymes break down the starches into fermentable sugars, so the longer the rest at 144-148℉ the dryer your beer will be (more sugars to ferment out). The alpha amylase rest will produce unfermentable sugars. The longer this rest lasts, the sweeter your beer. Keep in mind that it’s the same starches being converted, so it’s a balance between sweet/heavy and dry/crisp beer.

Typically, allowing 15-20 minutes for each rest will result in a well balanced brew. Start there and experiment over time and batches to dial in your preferences.

 

Happy Brewing!