Step Mashing...Why & When & How

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Well-Known Member
Jan 21, 2010
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I have been researching step mashes and came across an excellent set of blog posts from Chris Colby (Editor of BYO Magazine) on the website Beer and Wine Journal where he and James Spencer (Basic Brewing Radio) collaborate, post experiments & their results, as well as other helpful information. It's a great supplement to BYO Magazine. Anyway, I went through and put all the posts from the series together into one 11-page Word file to keep for myself. I thought I'd make a post with all the info here for those that might have missed this or perhaps (like me) never heard of the site. Here's the site for reference:

Choosing a Mash Method I - Single Infusion Mashes

When brewing an all-grain beer, you need to decide on a mash method. If you are following a recipe, the mash details are likely spelled out for you. However, if you’ve drawn up your own recipe--or are using an existing recipe and want to pick the best mash method for it — you should know how to choose a mash method.

Many homebrewers will choose their mash method based on the style of beer they are brewing — a single infusion mash for an English ale, a decoction mash for a German lager, or one of the slew of different mash methods used in traditional Belgian brewing for brewing a Belgian beer. (You will also need to decide on a lautering method — of which continuous sparging, batch sparging, and the no-sparge, brew-in-a-bag (BIAB) method are three popular choices for homebrewers.

Practical homebrewers should understand that mashing is an extension of malting and the vast majority of malts produced today are intended to be single infusion mashed. These malts are called fully-modified. Unless your malt is labelled otherwise, any base malt you buy is overwhelmingly likely to be fully modified.

Single Infusion Mashing
Most decoction or other step mashes have rests designed to degrade gums or proteins. In modern fully-modified malt, the grains are malted such that single infusion mashing will yield wort with an acceptable level of gums and proteins (and anything else you would change in a step mash). Putting a fully-modified malt through a step mash with a beta-glucan rest (or what used to be called a protein rest) is at best a waste of time and at worst it could have negative effects on your beer. For example, even fairly short rests (15 minutes) in the protein rest range can lead to less foam. As such, unless you have a good reason to do so, choose a single infusion mash as your mash method. It is likely to be your best choice.

If you know for certain that your malt has excessive gums or proteins, then a step mash may be just the thing. However, don’t perform a multi-step mash simply because you can do it. In most cases with fully-modified malt, a more complex mash schedule will not yield a better beer. Everything you would want to accomplish in that mash will have been done by the maltster. It can be fun to try traditional mash methods (decoction mashes, turbid mashes, etc.), but the malt you use will not be the same as the malt brewers historically used and won’t yield the same results.

If you want to brew something using a traditional method, go ahead, even if you are using a fully-modified malt. The beer will likely turn out fine (although perhaps not as good as it could have been). But be aware that — without the appropriate malt — you will not actually be fully mimicking the old school method.

Mashing Out
When performing a single infusion mash, you have the option of mashing out. For a mash out, the brewer raises the temperature of the mash to 168F–170F to decrease the viscosity of the mash, which leads to easier lautering and perhaps higher yields. This step can be skipped without causing too many problems, and indeed many homebrewers do omit it. However, if you expect lautering problems, are shooting for high extract efficiency, or trying to limit the fermentability of your wort (to make a sweeter, more full bodied beer), it’s best to mash out. Mashing out hastens the denaturation of the amylase enzymes and keeps them from continuing to work on the remaining carbohydrates in the mash.

Dry Beers
When brewing with fully-modified malt, there is one case in which a step mash will help you — when brewing a dry beer. To make a highly fermentable wort, which will yield a dry beer, mash in at 140F–145F and rest there before heating the mash into the low end of the regular single infusion mash range. The full range is often stated as 148F–162F, so ramping from the low temperature rest to 148F–152F works well. (I like ramping up to 152F, but that’s just a personal preference.)

You can hold the lower rest for up to a couple hours for a very dry beer, although 15 minutes should do it for a moderately dry beer. You can hold the higher rest so that the full mash time equals at least 60 minutes. The low temperature (140F–145F) rest should not have any negative impact on your beer.

By The Numbers
A single infusion mash is usually carried out at 148F–162F. The lower end of the temperature range yields a more fermentable wort, suitable for brewing a fairly dry beer, while the higher end results in less fermentable wort, which results in a sweeter beer. Temperature is the variable that influences fermentability the most.

The mash thickness of a single infusion mash typically varies from 1.0–2.4 qt. of brewing liquor per pound of malt, and the pH hopefully falls somewhere in the 5.2–5.6 range. (If it doesn’t, you should adjust the mineral content of your brewing liquor.) Thinner mashes, within the given range, produce slightly more fermentable worts.

Infusion mashes are frequently held for 60 minutes, especially at the homebrew scale. However, for sweet beers, you should perform an iodine test periodically and mash out immediately after getting a negative result. In contrast, if you want to brew a dry beer, extending the mash time (in the low end of the temperature range) will give the enzymes more time to work. For a “regular,” full-bodied beer, 45–60 minutes mash time will work well.

If you’re trying to brew a sweet beer, a mash out will help. It will also help if you are shooting for high extract efficiency. If you’re brewing a dry beer, you can skip the mash out and hold the wort in your kettle around 148F–152F while you are collecting it to give the enzymes time to continue working. If you do mash out, and you use continuous sparging, your sparge water should be heated such that it holds the grain bed at 168F–170F.

With most modern, fully-modified malts, a single infusion is your best bet. This should be your default choice, and you should have to talk yourself out of it to switch to a step or decoction mash.

The Steps in a Step Mash Part 1

Single infusion mashes work well when brewing with fully-modified malts. However, there are times when a step mash is more appropriate. In a step mash, the mash is initially rested at a temperature below the usual saccharification range, then raised through one or more rests at progressively higher temperatures. To raise the temperature, the mash may be directly heated, infused with hot water, or decoctions may be pulled, heated, and returned to the main mash. (Additionally, in a cereal mash, a mash that was initiatally separately from the main mash may be stirred in to raise the overall temperature of the combined mash.)

Performing a step mash is beneficial when using undermodified malt or home malted grains. In home malted grains — for which the degree of modification is likely to be uneven, compared to commercial standards — a decoction mash is likely your best bet.

There are historically relevant step mashes, such as the “standard” triple decoction mash, in which a specific set of rests is called for. On the other hand, any brewer can come up with his or her own step mash by choosing to rest or not at various temperatures. Here’s a quick rundown on the common steps found in a step mash, with some final thoughts on the overall mash program.

Doughing In/Hydration Rest (Ambient Temperature)
Some historical decoction mashes call for mashing in with unheated water for a short (roughly 15 minute) rest. Sometimes called a hydration rest, the idea is to give the mash solids some extra time to dissolve completely. Of course, solids dissolve into liquids more slowly at cooler temperatures and this is far below the gelatinization range of barley starch. Most homebrewers see this rest — correctly, in my opinion — as a waste of time. Stirring well at your initial rest temperature and letting the mash stand for an adequate amount of time overall should obviate any practical need for this rest. If you’re trying to mimic a historical triple decoction mash, then go right ahead. (Note that the term “doughing in” simply means to mix brewing liquor with malt — it is not associated solely with this rest.)

Acid Rest/Phytase Rest (95F)
Acids rests are most closely associated with triple decoction mashes. The mash is rested, frequently for as long as 2 hours, at around 95F. During this time, the enzyme phytase catalyses a reaction that slowly lowers the mash pH. The enzyme itself is active from around 86F to perhaps over 140F. Sources differ on that last point, and sometimes an acid rest might be conducted at temperatures up to 113F.

The key word in the previous paragraph is “slowly.” If you want any significant drop in your mash pH, you’re going to have to wait an hour or two. And, unless you are using undermodified or very lightly kilned base malt, the enzyme itself may not be present in sufficient quantities to bring about any change in pH. In more highly-kilned malts, the enzyme is destroyed by the heat during kilning. From a practical standpoint, you are far better off adjusting your water chemistry with the appropriate minerals, or adding acid, or adding some sauermalz (sour malt) or acidulated malt to your grist, or stirring in a small sour mash to adjust your mash pH.

Protein Rest/Beta Glucanase Rest (113F-122F)
Rests in this range degrade both proteins and glucans (gums). Proteins are acted on by proteinases that cut large proteins into smaller peptide strands. In turn, peptides are degraded by peptidases that reduce peptide to their constituent amino acids. Beta-glucan is a polysaccharide that can gum up your mash. A rest in this range allows the enzyme beta glucanase to degrade the glucan and help with lautering. These enzymes all have slightly different optimal ranges — the optimal temperature for a beta glucanase rest is sometimes given as 95F–113F, a peptidase rest is given as 113F–128F, and a proteinase rest is given as 122F–138F. However, these enzymes are all active over a broad temperature range and any rest in the vicinity of the temperature range given above will yield high levels of activity from all three. (Recall that enzymes are not turned on and off when they enter or exit their optimal temperature range; they are simply most active in that range. They may still retain significant levels of activity outside of the range.)

Generally, a 15–20 minute rest will give the correct amount of activity in an undermodified malt. In a fully-modifed malt, the level of proteins and glucans should be acceptable after a single infusion mash. In fact, a rest in this range can reduce protein levels to the point that head retention is affected. Some malts, such as wheat and rye malt, have higher levels of glucans (and also proteins), and may cause problems with lautering. In this case, a glucan rest may be beneficial, although generally just lautering slowly enough will usually do the trick. (The risks of a stuck mash from wheat or rye have been overstated by some sources.) These days, if a brewery is resting in this range, it is most likely to degrade glucans.

In the beta glucanase rest range, phytase is still active. However, given the short time frame, its activity (if it is even present) won’t amount to much. In this range, the amylase enzymes are also active. However, due to the temperature, their level of activity is low compared to what it will be later in the step mash. In addition, as this rest occurs below the gelatinization temperature of starch, the enzymes can only work on starch molecules on the outside of their granules. Still, a long (two hour) mash at 131F can yield over 90% of the potential extract of the grain. So, the amylase enzymes are working at these temperatures, just more slowly (and only for 15–20 minutes).

Starch does not need to be completely gelatinized for significant amylase enzyme activity to occur. (In living barley plants, gelatinization temperature is never achieved, but the amylase enzymes still work — albeit orders of magnitude slower than they do in the mash. If a seed converted all it’s starch to sugar in 60 minutes, it would die.) However, above gelatinization temperature, the increased activity of the enzymes and increased accessibility of the starch substrate make starch conversion go much faster.

With fully-modified malts, all of these rests can be skipped. The biggest exception would be if your malts were gummy (for example, if you were using a lot of rye malt). When using undermodified malt, a rest in the 113F–122F range is recommended. This should bring the level of gums down to reasonable range. With undermodified malt, you could try an acid rest, but there are quicker ways to achieve the proper mash pH.

The Steps in a Step Mash Part 2

The lower temperature rests in a step mash deal with hydration, mash pH, proteins, and beta glucans. They are not needed with most fully-modified malts, but work well with undermodified malts or home malted barley. Two of the three remaining rests deal with the degradation of carbohydrates — how starch is broken down into a mixture of fermentable sugars and unfermentable carbohydrates. These rests can be performed regardless of the type of malt you are mashing.

Beta-amylase Rest (140F–147F)
If you are looking to brew a dry beer, a rest in this range — in which beta-amylase is at its optimum — will help. A rest in this range produces a more highly-fermentable wort, with more of the short-chained carbohydrates (“dextrins”) reduced to fermentable sugars. Even if you are using fully-modified malt, you can rest in this range without negative consequences. (The protein-degrading enzymes may not be completely denatured yet, but resting here is not known to cause problems with foam.)

For a beer that is slightly drier than one made from a single infusion mash, try a 15-minute rest at around 145F, right near the optimum for beta-amylase, then bump the temperature up to 152–154F and rest for a further 45 minutes to 1 hour.

For a very dry beer, try resting at 140F–142F for 30 minutes to 2 hours before finishing the mash at a higher temperature. If you’re trying to make a dry beer, stirring the mash a few times will ensure it is mixed well and bring the enzymes and substrate into contact faster. (Especially in thick mashes, enzymes can get surrounded by their product, limiting their ability to bump into more substrate.)

Barley starch from malted barley typically gelatinizes in the 138F–145F range, but rests in the 140F–145F range are still very effective even if the starch hasn’t fully gelatinized. At a minimum, amylase enzymes can act at on starch at the outside of the granules.

Saccharification Rest (148F–162F)
This is the range for a single infusion mash. In a step mash, you can think of it as the finishing rest. At these temperatures, any remaining un-gelatinized starch will be fully-gelatinized and the amylase enzymes can complete starch conversion. If you’ve rested in the 140F–147F range, especially when brewing with malt with a high diastatic power, you may only need a short rest to finish things up. As short as 5 minutes might do the trick. (Use the iodine test to be sure.)

If you are using undermodified malt or home malted barley, and your previous rest was in the beta-glucase range, you may need to rest here for almost as long as a regular single infusion mash.

Step mashes can be time-consuming, especially when the mash is being heated and the ramp times between rests are fairly long. Using an iodine test to confirm complete starch conversion can let you know as soon as it is OK to proceed to the mash out. Factors contributing to a shorter required rest in this range include the use of high-enzyme malt (malt with a high diastatic power), a rest in the beta amylase range, and the longer times spent at lower-temperature rests.

Mash Out (168F–170F)
The reasons to perform a mash out are exactly the same as when considering a mash out in a single infusion mash. Given that step mashes can take a long time, some homebrewers skip this step. If you do, it is unlikely your beer will suffer.

General Thoughts
Step mashes tend to produce beers on the dry side, especially when higher diastatic power malts are used. (With undermodified malts, the effect may be less pronounced.) A beer made with a step mash ending at 153F is going to be more dry than a beer made with a single infusion mash at 153F. This is mostly due to the amylase enzymes being active (albeit at lower activity levels) at the lower temperature rests and the longer overall time the enzymes have to work on the carbohydrates in the mash.

If you want to brew a sweeter, more full-bodied beer, your best bet is a single infusion mash. Or, use a base malt without a lot of diastatic power, and keep the rests in a step mash — and the amount of time it takes to boost the temperature between them — as short as possible.

Choosing a Mash Method II - Simple Heated Step Mash Part 1

Sometimes the simplest approach is the best. When brewing with fully-modified malts — as most malts are these days — a single infusion mash is almost always your best bet. The maltster has taken care of many of the issues (gums, proteins) that would have required a step mash. In most cases, performing a step mash is at best a waste of time. At worst, it can decrease the quality of your foam. And, by varying the mash temperature of your single infusion mash, you can make wort with varying degrees of fermentability. For most styles of beer, this range of fermentability is adequate.

However, there are some times when a step mash is just the thing. If you are brewing with undermodified malt, a step mash is highly recommended. (If you single infusion mash, you may end up with too many proteins in your wort and gums (glucans) may make lautering difficult.) I’ll cover this approach in a later article on decoction mashing (a type of step mashing).

You can make wort with a fermentability high enough to make a reasonably dry beer using a single infusion mash. However, sometimes you may want to brew a significantly drier beer. For example, you may wish to brew a beer that is very hop forward. To do so, you may want to keep the body and sweetness from the malt lower than could have been achieved with a single infusion mash. Or, you might want to brew a very crisp, thirst-quenching beer for summer or after workouts. If you’d like to achieve a higher level of wort fermentability than can be obtained with a single infusion mash, to brew a correspondingly drier beer, a step mash can help you do so. And, a step mash need not be overly complicated or time consuming. Here is the simplest way to perform a step mash.

Simple Heated Step Mash
You don’t need a heatable mash tun to do a heated step mash — you can mash in your kettle and transfer the mash to your lauter tun when you are finished. If you have a RIMS or HERMS rig, of course, you can heat in your mash tun. I have a stainless steel mash tun with a false bottom. Although I could heat that directly, I prefer to do heated step mashes in my kettle because I think the false bottom traps heat. It’s easy to heat your mash in your kettle and simply scoop it over to the lauter tun when finished — easier, in my opinion, than raising the rest temperatures via infusions of boiling water or pulling decoctions.

To make a drier beer, from fully modified malt, you want to mash in to the range of temperatures in which beta amylase is most active. This range is often given as 140F–145F. The mash is rested in this range for a period of time, then the mash is heated into the saccharification range. The longer the low temperature rest, the drier the beer.

Beta Amylase Rest
To start a heated step mash, mash in at your normal liquor-to-grist ratio. Have the temperature settle into the 140F–145F range. If your goal is to brew a beer slightly drier than could be achieved with a single infusion mash, immediately begin heating the mash into the saccharification range of 148F–162F. If your goal if to brew a significantly drier beer, employ a longer rest before you start heating. In most cases, 15–20 minutes should raise the fermentability of your wort noticeably. However, for very dry beers, you can use even longer rests — up to a couple hours, even.

Heating the Mash
On most homebrew setups, heating the mash at a rate of about 2F per minute will work well. If you heat more slowly, the length of your brew day can get too long. Conversely, if you heat more quickly, the odds of scorching the malt or overshooting your next rest temperature increases. At 2F per minute, you’re heating relatively quickly and keeping the risks of overheating manageable. Your mileage may vary, depending on your system.

At 2F per minute, a ramp from the beta amylase range to the saccharification range will take between 6 and 44 minutes, depending on the initial and saccharification rest temperatures. A ramp from 140F to 152F, a very reasonable set of rests, would take 24 minutes.

As you approach your target rest temperature, back off the heat a little. I usually turn down the burner when I’m within 4F of my target and then again when I’m within 2F. This makes it easier to avoid or minimize overshooting the temperature. It takes time for heat to transfer from the metal of your kettle to your mash. So if you heat at a steady rate and only cut the heat right when you hit your target, the temperature will continue to climb a bit afterward. The amount of overshoot depends mostly on the how much heat is retained in the metal (which in turn is largely a function of how thick it is). Smaller overshoots can sometimes be dealt with by stirring the mash vigorously for a few minutes. Or, cool water can be stirred in to bring the mash temperature down.

When deciding how long to rest in the beta amylase range, be sure to consider both the duration of the rest, and the time taken to heat the mash to the next rest.

When heating your mash, you’ll need to stir it nearly constantly. It is very easy to scorch a mash when applying direct heat. This is doubly true for thicker mashes. Stir in circles that both move the mash horizontally and vertically. Essentially, stir so that the hottest bits of mash, near the bottom of the kettle, are swept up towards the top of the grain bed, not just rotating around the bottom of the kettle.

Choosing a Mash Method III - Simple Heated Step Mash Part 2

After the beta amylase rest (140F–145F), and the temperature ramp up into the saccharification range (148F–162F), the rest of wort production is almost identical to a single infusion mash. One difference is that you can choose a slightly higher temperature for your main mash rest. If you were brewing a dry beer and using a single infusion mash, you would likely rest in the 148F–151F range. If you were brewing a somewhat drier beer, you could mash in the 152F–154F range after the beta amylase rest. Because you’ve already rested at lower temperatures (favoring beta amylase), your main rest can be slightly higher, favoring alpha amylase a bit more, comparatively.

Both alpha and beta amylase will be active at both rests, just to varying degrees. In the beta amylase range, the activity of alpha amylase is still substantial (albeit less than it will be at the higher temperature of the saccharification rest). In the saccharification rest, beta amylase activity continues, although it will decline fairly quickly over time. Still — since it has already been working for a period of time at the lower rest — there is less substrate for it to deal with.

The amount of time you rest in the saccharification range depends on a couple variables. You could simply rest until you get a negative result in an iodine test. However, if you’re trying to make a dry beer, extending the rest beyond this point — and giving the enzymes more time to work — is probably a good thing. (A negative iodine test simply means that the level of starch has fallen below the threshold at which the test can detect it, not that starch is completely absent.) For a fairly dry beer, a 15-minute rest in the beta amylase range followed by a 45-minute rest in the saccharification range works well. The longer you rest in the beta amylase range, the shorter your rest in the saccharification range can be. However, I’d recommend spending at least 20 minutes there, even when employing very long beta amylase rests. (This recommendation is based on my experience and the idea that I’d rather be safe than sorry, not any hard data.)

Mash Out
When brewing a dry beer with a heated step mash, I would recommend mashing out — raising the mash temperature to 168F–170F — for two reasons. First, you’ll have a final temperature ramp through the high end of the saccharification range. This will give the amylase enzymes more time to keep working. (It’s not a big deal at this point, but every little bit can help when making a highly fermentable wort.) Secondly, if you’ve mashed in your kettle, the mash temperature will drop when you transfer it to your lauter tun. When I use this type of procedure, I mash out to slightly above 170F — usually around 180F — to counteract this. At normal mash thickness and pH, you don’t have to worry about extracting excess tannins by exceeding 170F — the usual stated grain bed temperature limit near the end of wort collection.

Before you scoop your mash to your lauter tun, add hot water under the false bottom (if applicable). When you’re done, simply rinse the kettle for use in the boil and proceed to recirculating your wort prior to runoff.

Speeding Things Up
A step mash — even a simple heated one — is always going to take longer than a comparable single infusion mash. You can speed up the temperature ramps by supplementing the direct heat with infusions of boiling water. I don’t do this when raising the temperature from the beta amylase rest to the saccharification rest. However, after heating the mash from the main rest to the top of the saccharification range, I sometimes use boiling water to quickly reach 170F or slightly over.

If you do use boiling water to speed your temperature ramps, you don’t need to add all the water in one single infusion. Estimate how much water you could add — without thinning the mash too much or overflowing your vessels — and the approximate time it will take to boost the temperature. Then use several small infusions to bump the temperature higher. You can cut the direct heat early and use a final boiling water infusion to bring your mash up to your target temperature.

Malt Choices
If you are trying to make a very dry beer, you may extend the beta amylase rest up to a couple of hours. If you do that, you will want to use high-enzyme malts — such as US 2-Row Pale Malt or US 6-Row Pale Malt. This will ensure you still have enzymes left when you heat the mash to the saccharification rest. And of course, minimize the amount of crystal or other “body” malts in your recipe to make the most highly-fermentable wort.

Next to a simple infusion mash, a heated step mash with two main rests (beta amylase and saccharification) is the simplest of all mashes. And, since you can mash in your kettle, you can perform this type of mash no matter what type of mash/lauter tun you usually use.

Mashing at 140F–145F will give the enzyme beta amylase some extra time to work, resulting in a more highly fermentable wort. Once fermented, this will result in a drier beer. For a beer slightly drier than one that could be made with a single infusion mash, mash in to the beta amylase range and then immediately start heating the mash towards the saccharification rest. For progressively drier beers, rest the mash in the beta amylase range for longer periods. You can rest there for up to a couple hours and still see some increase in wort fermentability (although the return on your time diminishes for longer and longer rests).


Well-Known Member
Oct 22, 2012
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Thanks for posting. I've been following this series in an attempt to better understand the decoction mashing process. I still enjoy an English bitter, and would like to try employing a step mash at Beta range to get a drier beer. Maybe 142F for 30 minutes, 150F for 30 minutes?