Controlling Mash Temperature – An Essential How-To Guide

by Dane Wilson | Last Updated: August 8, 2022

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Calling all-grain home brewers! Regardless of how much experience you have with all grain brewing, you can always delight in more tips to make the mashing part easier, right? After all, the best beer begins with the best mash; to get the best mash, controlling mash temperature is key. Understanding how the mash temperature changes the very nature of the wort is a good beginning, but this essential guide on controlling mash temperature will cover even more than that.

If you want a tastier beer, you have come to the right place. Let’s dive right in!

Table of Contents

• Why Does Mashing Temperature Matter?
  • Beer Body
  • Beer Mouthfeel
• Mashing Enzymes and Temperature Ranges
• More On Your Friendly Enzymatic Partners
• Proteins and Mash Temperature
• How to Control Mash Temperature
• When Your Mash Temperature is Low
• When Your Mash is Too Hot
• Ready, Set, Mash!

Why Does Mashing Temperature Matter?

Did you ever take a taste of a home-brewed beer and think to yourself, “Eh, it could be better”? Yeah, that is completely avoidable. You can add or subtract bitterness by choosing hop varieties for homebrewing. Flavors can also be imbued with more aromatic hops and later additions (adjuncts) during conditioning. But what about mouthfeel and body?

That stems from controlling mash temperature.

Beer Body

No, we’re not talking about beer bellies here. Body is another word for the thickness or weight of the brew. When a beer has body, it usually has a higher final gravity than one without much body. Lighter brews do not have the same consistency as a thick stout, for example.

Fuller bodied beers also have far more alcohol in them. However, you could brew up a full-bodied beer with a lower amount of alcohol just by controlling the temperature of the mash. Yep, it is that important.

Beer Mouthfeel

If you love beer, you love the experience of sipping on a variety of beer styles. One thing that you might talk about without even realizing it is the mouthfeel—the texture, taste, and serving temperature of the beer.

Is the beer creamy? Thick? Crisp? Thin? When you take a sip of Budweiser, you might describe the mouthfeel as light and watery. For a craft stout, the mouthfeel is most likely deep, rich, and heavy. Swap those mouthfeels for either beer style, and the beer would not be the same, would it?

Of course, the mash temperature plays a role, but so do the sugars, proteins, additives, and adjuncts added. The fun part is knowing that the mash temperature can release some of those necessary sugars and proteins.

If you want to know more about how mash temperature will affect your beer, check out this entertaining video:

Mashing Enzymes and Temperature Ranges

Why is mashing important? You need this significant step to assist with conversion, as in pulling the starches out of the grain and transforming them into fermentable sugars. Without fermentable sugars, you cannot have alcohol. Sugar also influences the body and mouthfeel of your beer.

Most styles of beer can be brewed with a single-step infusion mash, meaning that the conversion happens in a single step, without any acid or protein rests involved. If you want to do a decoction mash, then the temperature is increased and maintained at intervals. Doing so gives you the maximum amount of sugars for your brew.

Whichever you decide to use, the temperature of the mash is carefully maintained at around 146-156°F (63-69°C).

However, sugars are not the only thing you should be thinking about when controlling mash temperature. You also have enzymes and proteins to consider.

More On Your Friendly Enzymatic Partners

Enzymes are a special kind of protein that breaks down complex sugars, making them more readily available to the yeast. The temperature at which you mash your grains will release a variety of enzymes, which can affect your wort in a number of ways. Check out this nifty chart:

As you may already know, the most common temperature for mashing is 152°F (67°C). This temperature ensures that the grains release the fullest amount of alpha- and beta-amylase to give you the best amount of fermentable sugars.

Beta-amylase is useful, as it breaks down long chains of sugar into maltose. Alpha-amylase does the same thing, but it is faster at the job, processing the entire chain. Beta-amylase can only handle the ends. However, alpha-amylase creates some by-products. Finding the temperature sweet spot (around 153°F or 67°C) means you can balance these two enzymes.

In short, controlling mash temperature means balancing out enzymatic activity. The end result is better tasting beer!

Want to know more about enzymes in brewing? This video is great:

Proteins and Mash Temperature

Beta-amylase and alpha-amylase are the powerhouses during mashing, but they are not the only players. There are other proteins that you can utilize to add more complexity to your home-brewed beer. The proteins in question? Medium-sized proteins. These guys form a net, so to speak, adding to the mouthfeel of your beer and increase head retention. The technical term for this net is colloidal sol, and it is kind of like a gelatin but far less solid and wiggly.

No, you cannot turn your beer into jelly with just medium-sized proteins. The proteins are ideal for giving your beer a clear body without making the mouthfeel too thin.

If you want to create haze, you choose large-sized proteins.

So how do you use mash temperature to work in those proteins? By utilizing something called a “protein rest.” During the protein rest, peptidase—an enzyme—works on the medium-sized proteins, turning them into smaller proteins. This happens around 113-138°F (44-59°C).

However, you often won’t need to do a protein rest. Most grains used in brewing today have been modified to release starches ASAP. If you do a protein rest with modified grains, you could actually ruin the beer. That said, if you are brewing with unprocessed and unmodified oats, malt, or wheat, then a protein rest is just what you need to achieve a great mouthfeel.

How to Control Mash Temperature

With all variables removed, controlling mash temperature comes down to the science of checking the temperature consistently and using the right implements. Insulated mash tuns and containers are excellent tools to keep your mash from returning to room temperature too quickly.

One DIY-friendly method is to use a cooler—particularly for those making smaller batches of beer. Here is how you can use a cooler to maintain mash temperature:

1. Heat the water to strike temperature (check your recipe)
2. Pour the water into the cooler
3. Add grains to the brew bag and mix them with water
4. Take the temperature
5. Add the lid to the cooler and close it
6. Leave the mash alone for the right amount of time (again, check the recipe)
7. Stir the mash every 15 minutes

If you have a decent cooler, the insulating qualities will keep the mash from losing all of its heat. You can expect about a 2°F temperature drop in an hour.

Another way to keep your mash temperature from dropping or increasing too rapidly is to increase your batch’s mass. Heat-loss diminishes when you are working with larger amounts. Since the volume of the batch is greater than surface area in the mash tun or a brewing kettle, most of the heat remains locked within the wort.

When Your Mash Temperature is Low

Never fear, you can rescue your mash before it is unsalvageable. Heating your mash on the lower end of the 146-156°F (63-69°C) scale does have its advantages. For example, beta-amylase starts breaking down sugars into maltose. But if you descend too low, the starch conversion is going to halt, leaving you with bitter water instead of beer.

Sad!

So you need to increase the mash temperature, but how? Well, the easiest method is to add hot water. Boil some water then add it to the mash, stirring in the hot water until the temperature increases to the right temperature for starch conversion.

However, this can be problematic. First, you are increasing the volume of the wort, which may affect the final gravity. You could potentially subtract some of the water and use it for strike water later on, though.

The better option is to make your mash in a brew kettle, since you can heat the kettle directly. By keeping the heat low and stirring the mash consistently, you avoid scorching while maintaining mash temperature.

The last option is pulling off a decoction mash. You will need to separate the thickest part of the mash from the kettle and put it in another pot (make sure said pot has been cleaned and sanitized). Heat the decoction to a boil then return it to the rest of the mash. Watch the temperature increase. If the temperature does not reach your desired point, repeat the decoction process.

When Your Mash is Too Hot

You need a little heat to get those starches breaking down into sugars. Go too fiery, though, and your beer runs the risk of being bloated, having too high of a final gravity, and tasting bitter.

Fortunately, you can cool down your mash rapidly by adding cold water or ice cubes directly to the mash. Stir in the cold water until the target temperature is achieved. Just remember that this is going to affect your volume.

Option number two is a wort chiller. Pop your wort into the chiller and watch the temperature drop. Just don’t let the mash get too cold.

Ready, Set, Mash!

cnKnowing how to control mash temperature can ultimately change the nature of your beer. Whether you go with a hotter or cooler mash, knowing how to keep that temperature level will deliver unto you delicious beer. Use this guide the next time you make a batch of homebrewed beer. Whether you are aiming for something light and crisp or thick and foamy, controlling mash temperature is how you get there. Did we miss any tips? Let us know in the comments!