How Warm Should You Keep Your Mash? Facts and Info

While homebrewing can be a fun and rewarding experience, it can sometimes seem like rocket science. Among the most challenging yet crucial steps of the homebrewing process is ensuring the correct temperature of your mash.

You should keep your mash somewhere between 145°F and 158°F (63°C and 70°C). The average optimum for most brews is 152°F (67°C). Dry beers with higher alcohol content require lower temperatures, while full-bodied beers are mashed at higher temperatures.

Mash temperature is crucial when it comes to developing the qualities required for the beer you’re brewing. The right temperature level ensures comfortable conditions for all ingredients. In this article, you’ll learn more about the optimal mash temperature and how to achieve it.

Optimal Mash Temperature

While each beer style requires a slightly different mash temperature, there are specific general rules regarding a temperature range that ensures optimal enzyme activity levels.

Do not panic about messing up your mash temperature if you’re just starting. While it is important to follow the recommendations to create authentic, excellent-tasting beers, close is usually good enough. 

You will have enough time to study all nuances, but to start, keep in mind these general tips and stay in the optimal temperature range.

The Temperature Range for Proper Enzyme Activity

Enzymes are essential in a homebrewing process: they optimize mash pH and break down the proteins, but above all, they convert starches to simple sugars so that later on, the yeast would be able to convert the sugar to alcohol.

That is why we have to provide the most comfortable conditions for enzyme activity. Your mash is likely to contain multiple enzymes, all able to contribute to the quality of finished beer, and each enzyme type enjoys different temperatures for the best result.

Enzyme TypeOptimum TemperatureEffects
α-amylase154-162°F (68-72°C)Breaks complex sugars into more simple sugar chains.
β-amylase130-150°F (54-66°C)Breaks longer sugar chains into single maltose units, starting from the end of the chain.
Protease122-131°F (50-55°C)Breaks up proteins, reducing the haze and resulting in clearer beer.
Peptidase122-131°F (50-55°C)Further breaks up the amino acids released by protease, producing Free Amino Nitrogen (FAN). FAN is great for yeast health but can negatively impact beer flavor if present in excess.
Beta Glucanase95-126°F (35-52°C)Enhances sugar extraction and helps dissolve the starches.

As you can see, the temperature recommendations do vary. Your goal is to reach the average point comfortable for most enzymes. However, the task can get tricky with such a diversity of recommended conditions.

That is why most brewers concentrate on the two most important enzymes: alpha and beta amylase. You can see that I put them at the top of the table, emphasizing their crucial value. 

While you can also keep other enzymes in mind and reference their optimal temperatures, your goal would be to maximize alpha and beta amylase activity.

It is evident from the table that the average comfortable temperature for both alpha and beta amylase is between 150°F and 154°F (66°C and 68°C). That is the range most brewers go for, with a median value of 152°F (67°C).

Staying in that range or keeping as close to it as possible will ensure your mashing doesn’t go wrong. However, as I’ve mentioned in the beginning, the optimum range can extend wider, between 145°F and 158°F (63°C and 70°C).

That is because, with some beers, you want to stimulate certain enzymes more than others to achieve desired results in flavor, clarity, body, and aroma. Let’s clarify this point more and talk about when it can be beneficial to step to the lower or higher end of that broader range.

The Differences in Enzyme Activity

There are two factors that determine the most suitable temperature for your mash. First, you have to ensure the enzyme activity will be properly stimulated. 

And second, you need to analyze the desired qualities of your beer style, as mash temperature has a significant impact on the flavor and body of the finished beer. Let’s talk about how it happens.

As you can see from the table I provided earlier, the two main enzymes break complex sugars into simple ones. 

Beta amylase can start only from one end and slowly go through the sugar chain, creating single maltose sugar units that are very convenient for yeast to work with.

Alpha amylase, on the other hand, can start almost anywhere and works faster, but it leaves longer sugar chains that are less fermentable.

If you keep your mash at the optimum of 150°F-154°F (66°C-68°C), the enzymes will cooperate. Alpha amylase, which works more quickly, will break complex sugars into smaller chains.

These smaller chains are easier for beta amylase to break down further, as it has to start from one end and go through the entire chain one step at a time. 

In short, the work done by alpha amylase will help beta amylase break smaller chains into fermentable single units more quickly.

Such an approach produces medium-bodied beers with pronounced but moderately complex flavors. For instance, it works great for ales. However, if you’re going for another specific beer style, you might want to emphasize certain beer qualities and minimize the others.

Here’s why you might want to aim for lower or higher temperatures for your mash depending on the result you’re trying to achieve. 

These differences will change the flavor balance and emphasize the work of one enzyme more than another, impacting the taste and body. Let’s discuss these impacts in more detail.

Temperatures at the Lower End of the Range

The temperatures between 145°F and 150°F (63°C and 66°C) are considered the lower end of the optimum range. 

Enzymes will still work, but the activity of beta amylase will be stimulated more, while alpha amylase will feel less comfortable and thus will contribute less to the process.

Consequently, the highly fermentable single maltose units will be maximized in your mash. The process takes longer but results in exceptionally high fermentability. Once yeast enters the game, it will actively use the simple sugars to produce alcohol. 

As a result, you will get a very clear beer with a high alcohol content. On the other hand, it will also have a less pronounced taste, body, and mouthfeel.

This strategy is excellent for making dry beers. For instance, if you’d like to make a light and crispy lager, you’ll want to go for lower temperatures to achieve its neutral flavor, dry finish, and light body.

Temperatures at the Higher End of the Range

On the other hand, temperatures between 154°F and 158°F (68°C and 70°C) lie at the higher end of the optimum range.

Here, the activity of alpha amylase is emphasized, while other enzymes take a slight step back. As alpha amylase leaves longer and less fermentable sugar chains, the finished beer will have less alcohol content but be richer in flavor and body.

This approach is often used to brew stouts and strong British ales. They have intense aromas and complex flavors, usually a mix of fruit, caramel, toffee, nut, and malty undertones, depending on the recipe. 

Overall, higher temperatures result in full-bodied, rich, and complex beers. Take note if you’d like to experiment with designing your own beer. Slightly increasing the temperature is a great way to make your beer less thinned out and dry.

The Importance of Mash Temperature

We’ve discussed how differences in just a few degrees can impact beer flavor and enzyme activity. Still, the effects of mash temp on the finished beer are not limited to style adjustments. 

If you miss the target temperature completely, you risk ruining the beer or losing it at the very mashing stage.

So, what happens if you step out of the recommended temperature range? What effects on the finished beer can you expect? Let’s look at the research data to answer these questions.

Fermentability and Attenuation

Fermentation is what we call the process of yeast converting sugars to alcohol and producing CO2 and heat along the way.

The extent to which the sugars in your wort are converted to alcohol is a parameter referred to as attenuation. For instance, if you have 85% attenuation, it means yeast turns 85% of the sugars into alcohol content.

The temperature of your mash influences both fermentability and attenuation. The goal of reaching recommended temperatures is to create wort with these two qualities optimized.

While you can adjust temperatures to the limits of the optimum range, stepping beyond them can result in a rapid decrease in these two parameters.

What Happens When Mash Temperature Is Too Low

The critical point is going below 140°F (60°C). Extending the effects of lowering the mash temp to an extreme, you will get a very light-bodied, extremely watery beer with little to no flavor.

Alpha amylase will not show significant activity at this point, so mashing will take much longer and result in highly fermentable wort. You can expect the alcohol content to increase; however, the liquid you’ll end up with won’t taste good and won’t resemble beer much.

What Happens When Mash Temperature Is Too High

Temperatures about 167°F (75°C) and higher are considered too high. Beta amylase is less stable at high temperatures, so you can expect a significant decrease in its activity. A temperature of 176°F (80°C) and higher will deactivate beta amylase completely.

Alpha amylase, on the other hand, has a higher comfortable temperature range, which is why it will have to do most of the starch conversion. 

The result will be an almost 30% decrease in fermentability of the finished wort, as alpha amylase produces less fermentable sugars. Attenuation will also drop to about 45%, making the alcohol content significantly lower.

At about 185°F (85°C) and higher, both alpha and beta amylase won’t stand a chance. After 10 to 20 minutes, enzymes will be destroyed, which means a significant amount of starch will end up in the wort.

Tips for Adjusting the Temperature of Your Mash

It can be challenging to achieve the goal temperature for your mash and keep it stable throughout the mashing process, especially for less experienced brewers. 

However, now that I’ve explained how important the process is, I encourage you to try these simple and useful tips to achieve the best results and bring your homebrew as close to perfection as possible.

Raising Mash Temperature

The most straightforward method is to add some boiled hot water to the mash. Determining how much you need is rather intuitive, so add water in small portions, stir the mash between additions and check the temperature. Repeat until you reach the desired numbers.

Another way is to heat the mash directly. You can go for this method if you’re mashing in a kettle or using a RIMS or HERMS setup. Basically, you need a mash tun that can be directly heated, so this method won’t work for everyone.

Decreasing Mash Temperature

Similarly, you can lower the temperature of your mash by adding ice cubes. Drop them one at a time, stir well, and measure the temperature. Alternatively, you could go for some cold water, but I recommend using ice for a better end result.

If you would like to avoid adding volume and reperforming all calculations for possible additions, you can use an ice container. Put it into the mash and stir, then get it out once you reach your goal temperature.

You can also get a handy tool called a wort chiller. It has coiled copper tubing, which you put into your mashing tun to decrease the temperature. Similar to an ice container, it cools the wort down by running cold water through the tubing and doesn’t add any extra volume.

Conclusion

Mash temperature significantly impacts the quality of finished beer, so it is important to stick as close to the recommended values for your beer style as possible. 

Typically, the desired temperature falls somewhere in the range between 145°F and 158°F (63°C and 70°C). If you’re struggling to achieve your desired temperature, you can adjust it by adding some hot water or ice or by getting a professional mashing setup.

About HomeBrewAdvice

Hello, my name is Simon. Together with a group of writers I write about brewing beer and making wine. We all share a passion for the great things in life, such as making stuff from scratch.

The business of HomeBrewAdvice is to bring you great information, stories and product reviews from brewing at home, and making wine


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