How To Brew: The Complete Guide To Mashing

Having a successful mash is essential to brewing a delicious beer. Mashing is what converts the unfermentable starches into fermentable sugars. Along with converting the starches into sugars, mashing also needs to produce the right nutrients for the yeast, produce wort with the right flavor and color, and set you up for the next step – sparging. This article has everything you need to know about what mashing is, as well as how to maximize your own.

Mashing

Broadly speaking, mashing is mixing the grist with hot brewing water and holding it at a set temperature for a set amount of time. So, the main things we must control are:

  • The temperature of the mash
  • The time we mash for
  • The ratio of grain to water
  • The brewing water we use

We discuss all of these in greater detail below, but before that, let’s quickly talk about the sugar we produce.

Sugars

Before we jump into the process, we first want to talk about the types of sugar we produce in the mashing process. These include glucose, maltose, maltotriose, and dextrins. Maltose is the most common sugar found in wort and is made up of two units of glucose. Maltotriose is made up of three units of glucose. Glucose, maltose, and maltotriose are all fermentable by yeast. The fourth type, dextrin, which is discussed in the enzyme temperature subsection, is not fermentable by the yeast.

In addition to sugars, the enzymes also break down proteins into amino acids, which are essential to yeast health.

Temperature

The temperature control must be precise in order to achieve the goals mentioned above. The two temperatures we discuss here are the gelatinization temperature of the malt and the optimal enzyme temperatures. If you are not in these temperature ranges, you will not produce the product you are expecting.

Gelatinization Temperature

Barley holds starch as granules, and these granules do not let water in. If the water cannot reach the starch, then the enzymes cannot access and convert the starches. To fix this, these granules must be gelatinized. Gelatinization is the rupturing of these granules on a microscopic level. For barley, the gelatinization temperature is around 142 degrees Fahrenheit. Once we have considered the gelatinization temperature of the starch granules, we must set the optimal environment for the enzymes to work.

Enzyme Temperatures

There are two main enzymes that work above gelatinization temperatures – alpha-amylase and beta-amylase. Both of their optimal temperatures are listed below.

  • Alpha-amylase has an optimal temperature of 161 degrees Fahrenheit
  • Beta-Amylase has an optimal temperature of 145 degrees Fahrenheit

Alpha-amylase works by randomly chopping up the starch chains. Beta-amylase attacks the ends of these starch chains, producing maltose. Alpha-amylase occasionally produces chains that are too long for beta-amylase to attack. These are called dextrins and are unfermentable by the yeast. These dextrins add fullness to the beer.

There are two other enzymes, beta-glucanase and protease, that are useful in less-modified malts. If you have heard of a step mash, these are the enzymes utilized in the first couple of steps. Beta-glucanase is optimal between 104 – 122 degrees Fahrenheit and breaks down beta-glucans. Beta-glucans are gums and can cause a stuck mash. Protease is optimal between 122 – 129 degrees Fahrenheit, and they break down proteins into polypeptides, peptides, and amino acids. Well-modified malts do not need these rests. Using a protein rest on well-modified malts can cause the enzymes to break down too much protein, leading to poor foam quality and a thin beer.

Time

We need the time to be long enough to convert the starches to sugars, but not so long that we break down more than we’d like. Mashing for too long can cause the enzymes to break down too many proteins and dextrins, which results in a thin beer. A good rule of thumb is 60 minutes.

Grist To Water Ratio

Next, we have the ratio of water to grains. If the mash is too thin, the enzymes become diluted, which slows the conversion. A good baseline is 1.25 quarts of water to 1 pound of grain. So, if you have a grain bill that is 10 pounds, you want:

(10 lbs)(1.25 qts/lb) = 12.5 quarts or 3.125 gallons

Water Profile

You can find a complete guide to designing the perfect water profile here. You want to maximize the ions of calcium, sodium, sulfate, and chloride. In addition to these ions, you need to have your mash pH at an appropriate level. Mash pH is ideally between 5.2 and 5.4. To lower the mash pH, you can add a small amount of phosphoric acid. You can also add calcium, which removes phosphate and lowers pH. To raise mash pH, which can be necessary for beers with large amounts of roasted grains, add bicarbonates in the form of pickling lime or baking soda.

Performing a Successful Mash

Now that we know the key parameters that make up the mashing process, let’s move on to how to design your own mashing profile. The two parameters we customize here are temperature and time. The grist-to-water ratio stays relatively constant, and developing a perfect water profile is beyond the scope of this article, but you can find our brewing water profile guide here.

Choosing Your Mashing Temperature

The temperature has major implications on the characteristics of your beer. As mentioned above, the different enzymes play different roles. We can adjust the temperature to optimize these enzymes. For example, we can hold the mash at lower temperatures to optimize beta-amylase. This produces more fermentable sugars, resulting in a drier beer. We can likewise hold the mash at higher temperatures to optimize the alpha-amylase. This produces more dextrins, or unfermentable sugars, resulting in a fuller-boded beer. Most beers, however, have a mash temperature right in the middle to produce a mix of both fermentable and unfermentable sugars, resulting in a balanced beer. These temperatures and their characteristics are below.

  • Mash at 148 degrees for a drier beer
  • Mash at 152 degrees for a neutral beer
  • Mash at 156 degrees for a fuller-bodied beer

Choosing Your Mashing Time

As mentioned above, you want to mash for just long enough to get the sufficient conversion, but not so long that you start to break the sugars down too much. We can similarly manipulate the time to optimize our wort’s profile. For drier beers that are light in body, we can mash for longer. This allows the enzymes to work longer, converting more starches into fermentable sugars. We can have shorter mashing times for beers that are fuller in body. This prevents the enzymes from breaking down those dextrins. For neutral beers, we split the difference. We have common mashing times with the above mashing temperatures listed below.

  • Mash at 148 degrees for 75 minutes for a drier beer
  • Mash at 152 degrees for 60 minutes for a neutral beer
  • Mash at 156 degrees for 40 minutes for a fuller beer

Example Mash

When mashing in, you must stir the grains in as you add them to the water. If you do not stir, the grist may clump together and form dough balls. This prevents water from reaching the grains on the inside of the dough ball, reducing the amount of sugar you can extract. Once the grain is stirred in, the wort is commonly pumped from the bottom of the mash tun through a false bottom and recirculated to the top of the grain bed. If you do not have a pump, you can use gravity to pull off small amounts of wort at a time and then gently pour the wort back onto the grain bed. The false bottom allows the wort to pass through but keeps the grains from recirculating along with it. This recirculation sets up your grain bed, which will filter the wort and clarify it, which you can see below.

Now that we know everything we need to about the mashing process, let’s do a walkthrough of a real mash, courtesy of our sweet stout.

Sweet Stout Mash

The sweet stout is a full-bodied beer, so we mashed it at 156 degrees for 40 minutes. We took samples every 10 minutes and measured the pH and brix (sugar content). We recirculate our mash continuously to set up our mash bed and filter the wort. You can see the color development and clarifying effects of the mashing process through these pictures.

Mash at 10 Minutes

Mash at 10 minutes
Wort at 10 Minutes Into the Mash

Here you can see that there is already some color and sugar development, but hardly any clarity. The 8.8 brix converts into a 1.035 gravity. The pH has not dropped yet but will continue to do so as the roasted malts work their magic.

Mash at 20 Minutes

The mash at 20 minutes.
Wort at 20 Minutes Into the Mash

There are significant color development and clarity improvements. We have also continued to convert starches to sugars with our Brix raising to 10.6 from 8.8 (1.043 from 1.035). The pH has dropped into the prime mashing pH range.

Mash at 30 Minutes

The mash at 30 minutes
Wort at 30 Minutes Into the Mash

There are, again, noticeable color development and clarity improvements. We also achieved additional conversion, as the Brix increased to 12.6 from 10.6 (1.051 from 1.043). The pH has remained constant thanks to our added bicarbonates.

Mash at 40 Minutes

The mash at 40 minutes.

There are not many changes between the 30 and 40-minute mark. The color is the same, and the Brix only increased slightly to 13 from 12.6 (1.053 from 1.051). This is because the majority of mash conversion takes place by around the 30-minute mark.

Wort at All Stages

The wort at all stages of the mashing process.
Wort at Different Stages of the Mash

As you can see, the wort changes drastically throughout the mashing process. We included two additional samples in the above picture that we will cover in later posts – pre-boil and post-boil samples. The pre-boil lightens in color and sugar concentration due to the sparge water, and the post-boil is darkened by the Maillard effect in the boil. All of these work together to create the beer we want.

Closing

You now know everything you need to perform a successful mash. You know the optimal temperatures to utilize the different enzymes, the time it takes to achieve conversion, and the results you hope to attain from the mashing process. To see what mashing profiles we use with different styles of beer, check out our beer recipes page. As always, please feel free to reach out to us at brady@thebeerjunkies.com with any questions or comments. Cheers!

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