(Last Updated On: December 4, 2018)

What is Step Mashing?

Short Answer: Step mashing is a part of traditional all-grain brewing, using multiple mash rests to help enzymes in the malted grains to convert starches into fermentable sugars.

Step mashing is far less prevalent today than in days past, but that doesn't mean it has no benefits for modern all-grain brewers! Click To Tweet

Even though today’s maltsters are producing highly modified malts (which don’t need nearly as much help in the conversion process) step mashing can still be an important tool to help you dial in specific characteristics in your beer.

To understand the process of step mashing and why it may (or may not) be beneficial to you, we should talk a bit about malt modification.

What Is Malt Modification?

Malt Modification is a general term that describes some of the processes maltsters use to make modern malts easier to use for brewers.

Malting is a critical process when it comes to brewing beer, and modification is the primary goal of the malting process.

Maltsters take raw grains (most commonly barley) and allow them to begin germination. Prior to sprouting, the grains are kilned lightly to stop the germination process.

Most of today’s malted grains are considered ‘highly modified’.

This benefits brewers in a number of ways.

Glucans and proteins in the cell walls of the barley (or other grain) begin to break down

Amino Acids are created which are beneficial to yeast health

Enzymes are made available which perform the magic of mashing: converting starches in the grains into fermentable sugars

Taken together, all of these malting processes contribute to modification.

Modern malts are so highly modified that the proteins and glucans are almost completely broken down before the malt ever makes it into the brewer’s hands. This eliminates some hurdles brewers of old had to deal with.

Modern brewers are primarily concerned with and responsible for the final step: converting available starches into sugar during the mash process.

What Is a Mash Rest?

A mash rest is simply a period of time where the mash is held (“rested”) at a specific temperature to allow a specific chemical reaction to occur.

Each of the various enzymes found in the malted grain performs best in a specific temperature range.

And each one also has a specific ‘skill’ it is best at, such as breaking down a certain protein or starch compound.

By holding (or resting) the mash at these specific temperatures, these enzymes get a chance to do their work, which can change the characteristics of the wort that is produced.

Does Step Mashing Really Matter Anymore?

Like many things in homebrewing, it really depends.

I suppose we are really comparing the pros and cons of step mashing vs the most common mash technique used by homebrewers: the single infusion mash.

A single infusion mash is one where (you guessed it) a single infusion of mash water is combined with the grist, and the entire mash is completed at roughly the same temperature.

So for starters let’s look at a VERY basic rundown of the trade-offs between Step Mashing and Single Infusion Mashing.

Step Mashing Vs Infusion Mashing

Complexity

Single Infusion mashing is certainly more simple than step mashing.

This is because you can simply heat your strike water to the desired temperature and let it be.

With step mashing, you need to be able to periodically raise and hold the mash temp.

This can be done either via direct heat, or by using multiple infusions of hot water. Each has pros and cons, and the mash-tun design you use may force your hand on this one.

If you have a mash tun that can be safely heated on the stove or a propane burner, you have the option to use either direct-heat or multi-infusion for your step mashing.

More on that later.

Time

Single Infusion mashing gets the nod for being quick and easy as it’s just a single rest.

Step mashing typically results in a longer overall mash time due to the length and management of the various rests.

Fermentability

Step mashing can arguably produce a more fermentable wort, as more time and care has been given to breaking down all of the compounds in your grains.

This is much less of a factor with today’s highly modified malts. In the past, step mashing was almost a necessity.

But that doesn’t mean that step mashing can’t provide some benefit to modern brewers. Controlling the mash is one of the biggest ‘dials’ all-grain brewers have when it comes to having absolute control over the finished product.

Beer Quality

This is almost 100% subjective.

An Exbeeriment done by the Brülosophy crew in collaboration with House of Pendragon had some interesting results. They compared a single infusion mash to a step mash on an otherwise identical recipe.

In a blind triangle test, a statistically significant number of tasters were able to tell that the beers were different, but the preference between the two was very very close.

There was also a small but present difference in the OG of the beers, with the step mashed batch ending up .003 higher than the infusion batch.

They finished at the same FG, indicating that the step mash process did provide a more fermentable wort.

How Does Step Mashing Work?

Step mashing is all about giving various enzymes time at their optimal temperature range to work on the mash before becoming denatured.

This allows each compound to be more effectively broken down by a specific enzyme and converted into sugars and helpful amino acids, resulting in a more fermentable wort.

How Enzymes Work In The Mash

Let’s use a simple analogy and pretend that enzymes are like little robots.

When water is present at a given temperature, our little buddies get to work. What kind of work? They break stuff.

Stuff like starches. When an enzyme binding two molecules of sugar on a starch strand is exposed to water at the right temperature, it breaks the bond between the sugars and the starch.

This keeps happening and breaking that starch strand into sugars.

Various enzymes have different active ranges, meaning they work most efficiently around a given temperature. There is some wiggle room here.

Our friendly enzyme robot can get a little bit of work done if the temperature is cooler than its “preferred” range, but it won’t be as efficient. It will take longer to do the same work.

Warm it up some, and work gets done quicker, as with most chemical reactions.

If the temperature gets too high, our poor little enzyme-bot breaks down and stops working completely! When this happens, we say that the enzyme has become “denatured”. Many enzymes will eventually denature even in their optimal temperature range.

Hey, nothing lasts forever!

Mash Temperature Chart

Enzyme Name Optimal pH Range Optimal Temp (F) Optimal Temp (C) Job Phytase 5.0-5.5 86-126 30-52 Acid Rest used to lower mash pH. Not typically used these days. Debranching 5.0-5.8 85-113 30-45 Used to make starches water soluble Beta Glucanase 4.5-5.5 95-113 35-45 Breaks up glucans (gummy substances), help prevent stuck sparge Peptidase 5.6-5.3 113-131 45-55 Releases Free Amino Nitrogen – Good for yeast health Protease 4.6-5.3 113-131 45-55 Destroy larger, gaze-forming proteins Beta Amylase 5.0-5.5 131-150 55-66 Create Maltose (fermentable sugar)

from available starches Alpha Amylase 5.3-5.7 154-162 67-72 Produce additional fermentable sugars, including Maltose

This table shows a list of the major enzyme categories that are typically active in a mash, along with their optimal temperature range and the compounds they work with.

CREDIT: The information in this table comes from the fantastic ‘How To Brew‘ by John Palmer. That book has everything you might ever think to ask about mashing!

There is an online version of the 1st edition, but I own and prefer the latest paperback edition.

Observations

By looking at this table, we can deduce a number of things.

Mash pH

Mash pH has an effect on enzymatic activity. While each rest has a slightly different active pH range, there is a lot of overlap.

This is why you typically see recommendations to keep mash pH around 5.2-5.5. Closer to 5.2 will be more effective across mast rests.

You can check your mash pH with an electronic meter or with test strips to make sure you are in the desired range.

Mash Rest Overlap

As you can see, a number of the enzymes in the table share the same preferred temperature.

For example, a mash rest between 95 and 113F at a pH of 5.2 will be in the optimal range for Phytase, Debranching, and Beta Glucanase enzymes. If you stay closer to 113F, that same rest will also be at the lower end of the range for both Peptidase and Protease.

Beta Amylase and Alpha Amylase don’t appear to directly overlap, but a fairly common mash temp for single infusion brewers is 152. This is right smack between the optimal ranges of both beta- and alpha-amylase.

That rest will produce a quite fermentable wort, as both enzymes will be active, though slightly outside of their optimal range.

Taken together, we can accomplish an effective step mash program with 3 or even just two rests, but you can break it down as far as you are willing. The important thing to understand is that enzymatic activity is not like a light switch.

It can take place below or above the optimal temperature range, though a given enzyme will work more slowly at lower temperatures, and eventually become denatured (deactivated) at higher temperatures. The higher the temperature, the more quickly the enzyme will denature.

Example- A 3 Step Mash Program

Step 1 – The Dough-In

Temperature – 100-105F, Time: 20 Minutes

This first step could be argued to be unnecessary with today’s highly modified malts, as the majority of debranching has already occurred during the malting process.

That said, it’s not uncommon to dough-in (combine your strike water with your grist) at a lower temperature (100-105F) for a short rest to allow any leftover debranching to occur, as well as allow the Beta Glucanase some time to work.

This step can potentially yield a lower viscosity wort (less likely to gum up the works when sparging/lautering) as well as add a couple of gravity points.

Step 2 – Protein Rest

Temperature – 120-130F, Time: 20 Minutes

Again, there is some debate as to the necessity of a protein rest for modern brewers, as most of this work will have been done by the maltster.

As a matter of fact, it should really only be performed if the grist contains a decent amount of under-modified malts, or flaked grains with high protein content. And only then if you are not looking for the head- and body- increasing properties these malts and grains can provide.

Executing a Protein Rest on a recipe with mostly highly modified malts should usually be avoided, unless you are specifically going after a very light body and mouthfeel.

That said, a 20 minute rest at about 125F is appropriate if you are trying to avoid haze caused by high protein content in the grist, keeping the previously mentioned caveats in mind.

Step 3 – Conversion Rest

Temperature – 145-162F, Time: 40 Minutes (or longer)

Also known as the Saccharification Rest, this is where the bulk of starches will be converted into maltose and other fermentable sugars. This is also the step where you can potentially have a significant impact on the fermentability of your wort.

A mash temperature of about 152 is very often recommended, as it provides a good compromise for both beta- and alpha- amylase to activate.

You can use this rest as a “dial” to affect fermentability of your wort.

Leaning towards the high end of this range (closer to 160-162F) will produce a less fermentable wort, which in turn leads to residual sugars in the finished beer, and (as many believe) a fuller, potentially sweeter mouthfeel.

Conversely, if you stay closer to that 145F mark, you can potentially end up with more fermentable sugars, which lead to a lower final gravity, and a drier more crisp mouthfeel.

An extended rest right around 152F will most likely give you the best of both worlds, so to speak, which is why it is such a commonly quoted mash temperature.

How To Step Mash

Multiple Infusion vs Direct Heat

To accomplish a step mash, you need a method to increase the temperature of the mash for each step.

If your mash tun can be heated directly, this isn’t too difficult, but there are some potential gotchas to be aware of.

Owners of plastic beverage-cooler style mash tuns will need to add calculated amounts of near boiling water to bring up the mash temp for each rest.

The infusion calculations can be tricky, but you only have to stir when adding the water, as opposed to the constant stirring required when raising the temp via direct heat.

Direct Heat Step Mashing

If you are using a kettle or other direct-heatable vessel as a mash tun, it’s easy to simply apply heat until you hit your next mash rest.

It’s very important to stir the mash while applying heat. This is for two reasons:

To prevent scorching

To maintain an even temperature throughout the mash.

Without stirring or some form of recirculation (such as a RIMS system), the bottom of your mash will be much hotter than the top, and you may even burn or scorch the grains at the bottom.

Stirring also allows you to accurately measure the temperature of the mash. It’s typically a good idea to cut the flame a couple of degrees before your target, and let the residual heat bring you the rest of the way.

Multiple Infusion Step Mashing

Brewers can accomplish a step mash by adding multiple infusions of boiling water to the mash at each rest.

The boiling water is combined with the existing mash, and brings up the mash temp to the next rest target.

It can be tricky to calculate the correct volumes to add to hit a target mash rest temperature. Luckily, Brewer’s Friend has a handy Mash Infusion Calculator to help you out.

Recommended Reading

John Palmer’s ubiquitous ‘How To Brew’ has a fantastic section on Mashing in general, including specific information about typical rests and all of the enzymes at play. One my most highly recommended homebrewing books.

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