Mash Profiles: What you need to know


how to quit worrying and leave your mash the hell alone

This talk was given on January 10th, 2022

When I first started brewing, as is common, I had some misinformation about mash profiles and what is the “best” mash profile and what equipment one should have in order to achieve the best mash possible - as one does when they start a new hobby and delve head-first into it. There’s simply too much information out there and not all of it is quality, which is why I took formal brewing education. 

The reality is that all mash profiles have their places because they all achieve different things. It’s like sports cars and dump trucks. One’s a lot flashier than the other, but good luck hauling gravel with it. In order to figure out which one you need, you need to understand what it is you need to do, so we’re going to go through the various mash profiles as well as the steps that happen, what they do and why you might want to use them. 

The oldest mash profile in the world is the single infusion. I made a comment recently that every brewery textbook wastes its entire first chapter talking about Sumeria as though we haven’t all heard the story before, but in this case, it’s relevant. The Sumerians would take green malt, soak it in water and then let it sit in the sun, where it would easily get up to mashing temperatures. It would be quite unpalatable to us - similar to drinking weak, unboiled mash runoff, but relatively calorie dense. The Egyptians would brew similarly, but they used bread instead of green malt and with that, we end up with the first two steps in malting - modification and drying. Drying allows the malt to be broken up

To very quickly gloss over how malting works, once the grain sprouts, a process happens in the kernel’s storage system that breaks down dried starch reserves into sugars to feed the growing plant. Maltsters manipulate this process in germination tanks and stop it right when they’ve achieved the degree of modification that they want. For well modified malts, they’ll allow this process to go on a little longer and for less-well modified malts, they’ll stop it sooner. Like everything, it’s a trade-off and for well modified malts you get:

  • Less sugar
  • Less protein
  • Less diastatic power
  • Less beta glucans

For less well modified malts, you’ll get the opposite. Most malts on the market today are well-modified, with standard North American 2 row leaning into some aspects of less well-modified since it’s been selected for years to cater to the macro lager industry, though that has been slowly changing over the past decade. 

Why does this matter? Because the single infusion mash is best for well-modified malts. The less well-modified a malt is, the worse it will perform in a single infusion mash. Most brewers, including small commercial brewers, only have the ability to do single infusions. Home brewers can actually be much more flexible for much less money because the efficiency of a heating system will decrease exponentially with the amount of liquid you need to heat, even if you increase them at the same relative rate. 

What a single infusion mash profile does is put all of your faith in the maltster and you just have to choose your sugar profile - sweeter or drier and then modify your time and temperature to get there. Having said that, I highly recommend trusting your maltster as we supply most of North America with the malt grown right here and we have the most expertise when it comes to malt, although this year is gonna suck for malt, which I might talk about at the next education session. 

What if, though, you don’t trust your maltster or more likely, you just want to play around some, cause you sure as hell aren’t going to do a better job than they are. For that you have the other mash profiles, which essentially boil down to temperature mashes and decoctions. For that, you have to get less well modified malt. Using these mash profiles with well modified malt will land you in a heap of trouble - namely overly dry beer, excess protein in the boil, beta glucans everywhere and little to no foam stand. No-one wants a dry, headless beer that oxidises immediately. 

Let’s go through our two options, starting with the temperature mash. This mash was invented in Belgium for tax purposes and has one goal - maximising efficiency. Before we delve too deep into that, let’s talk about what we mean when we say “efficiency”. 

Simply put, efficiency in a mashing context, is the total amount of sugar that you can get out of a given amount of grain. There are tests that maltsters perform that give you a maximum theoretical yield for a given malt and your efficiency is a percentage based on that number. I should add that it is possible to get over 100% efficiency with these profiles because the standard test maltsters use doesn’t take into account a few things, but we’ll just say that most commercial operations aim for somewhere in the 96-100% range. 

Enzymes have optimal ranges for pH, temperature and osmotic pressure and there are a variety of them, some good, some detrimental (like LOX) and they are all slightly different. Generally speaking, brewers aim for a pH of 5.2 because it’s a good middle ground for the enzymes we want while being less than optimal for the enzymes we don’t. Subtypes of the temperature mash, like the double or even triple infusion mash, also attempt to match osmotic pressure preferences for optimal enzyme activity. The thing with most enzymes though, is that they are time sensitive once they are activated. Most of the enzymes we care about will give you about an hour of functional activity before they start to drop off. 

So for a quick refresher on malt modification, we’re looking at four things:

  • How much sugar/potential sugar is there?
  • How much protein is there?
  • How much diastatic power is there?
  • How much beta glucan is there?

Protein and diastatic power are very closely linked, which brings us to our first step, the Protein rest. You’ll notice that I’m ignoring the acid rest and that’s because there are extremely limited scenarios in which it functions, none of which are possible with Edmonton water and if you’re using different water sources, you might as well just add acid and skip the rest because you greatly increase the likelihood of oxidising your beer. 

The protein rest does two things - it releases protease enzymes that chop up the proteins into free amino nitrogen, which is useful for yeast (though can lead to excess growth in high quantities, making fusels) . The second thing it does is make new enzymes - hence why protein and diastatic power are very closely linked. The longer your protein rests, the shorter your other rests are going to be because you simply have turbocharged diastatic power. If you don’t understand all the things that a protein rest does and you continue your mash with unaltered mash times, you’ll end up with the aforementioned disaster. 

The next two steps are saccharification and liquifaction, though you’ll only see the term “liquifaction” in textbooks. Saccharification is the process of turning starches into simple sugars, specifically maltose and glucose, both of which are highly fermentable. The think to remember about saccharification, however, is that the enzyme that does it, B-amylase, is only able to access certain parts of the starch. Think of the starch molecule as a big long tree trunk with a bunch of branches. B-amylase will nibble on the tips of the twigs, biting off fermentable chunks until it hits another branch, at which point, it will look for another tip to start nibbling on. What you end up with is a big long starch molecule that’s been stripped of all its twigs and so what’s left is highly fermentable, but not very efficient since there’s still a lot of sugar locked up in that starch molecule. It also takes quite a bit of time since B-amylase is quite slow. This is what you’d be doing if you did a single infusion and targeted a low temperature of 148F/64C for 75 minutes. With a protein rest, you’ll speed this up somewhat, but you’ll still be left with an inefficient mash since there’s only so much B-amylase can do.

The liquifaction step literally liquifies the starch (hence the name). You can actually see the liquifaction happening in your mash if you move it from a lower temperature to a higher temperature, it suddenly gets a lot easier to move. This is where A-amylase resides. A-amylase It does not care about trees or tree branches, it just picks a spot and chops. The end result is very little starch left, but lots of non-fermentable sugars. The beer ends up sweeter because your tongue can process dextrins, but not the starches that B-amylase leaves behind - though ideally those starches don’t make it into the boil kettle. 

The point then of a temperature mash is to squeeze every last bit of efficiency out of your malt by first turbocharging your enzymes with the protein rest, making sure you’ve got lots of fermentable sugars with the saccharification rest and then breaking up the remaining starches with the liquifaction rest. As I said though, the original goal of this mash profile was avoiding taxes. In Belgium, taxes were first assessed based on the amount of malt used and then based on the size of your mash tun, which led to the increased use of adjuncts. 

Now I can reliably increase my efficiency over single infusions by anywhere from 20-30% using a temperature mash, which sounds like a lot, but that restricts me to using less well-modified malts. Doing that with a well modified malt simply won’t work. Even if I was trying to make a super dry and foamless beer, well modified malts just don’t have as much starch to turn into sugar. The other variable is capital cost. On a home brew scale, 20-30% is a huge boost, but on a commercial scale, ramping up temperatures on huge mash tuns means bigger boilers, more steam tubes, better circulation and then the maintenance of all that equipment. Unless you’re selling thousands of hectolitres a day, the math is never going to make sense. 

The last thing I want to touch on before I move on is that a temperature mash profile is going to involve stirring and disturbing your grain bed each time you need to increase the temperature. By default, this is going to increase the amount of beta glucans in your beer and shorten its shelf life as hot side aeration becomes inevitable. I know there was a debate awhile back about hot side aeration and I don’t want to get into the specifics except to say that for homebrewers, it absolutely is an issue. 

I saved the best mash profile for last, and that’s the decoction. I say “best” tongue firmly in cheek because it’s held to this mythical standard. The profile has so much cachet that when ABInBev bought Pilsner Urquel, they sunk a ridiculous amount of money into preserving the ability to decoct into their new brewhouse, even though most consumers wouldn’t notice a difference if they altered the recipe slightly. 

Decoction stems from the old days before thermometers when the only things you could measure were volumes, weights and whether or not something was boiling. Through massive amounts of trial and error, a brewery would figure out exactly how much mash to ladle out and then boil in order to achieve the sugar spectrum they wanted. Gravities were hit or miss due to several factors, but it functioned essentially the same as a temperature mash, with less accuracy. 

The strange thing that is completely accidental with decoctions, is that while you do everything you aren’t supposed to do with a mash, if you do it correctly, you end up with a bunch of melanoidens that not only confer flavour, but also protection against the oxidation that normally occurs hot side - which is awesome because very few breweries that still do decoctions also do the other things that make hot side aeration irrelevant. 

Just like the temperature mash, decocting well modified malts is a terrible idea. Your efficiency may go through the roof, but you won’t get the sugar spectrum you want. 

Having said all that, which malt profile is right for you? Most likely single infusion. Almost all craft beer producers use it and most people seem to think it results in some pretty great products. However, if you want to chase that efficiency and tweak sugar profiles AND you have the ability to do so, try making some Belgian ales and play around with the saccharification and liquifaction rests. Unless you’re using chit malt, a protein rest should be about 30 minutes, but start with 15 minutes each on the other two rests and then play around 5 minutes here or there. Do be aware that this requires experimentation and you’ll be drinking Belgians all year. Or throwing amazing parties. 

Lastly, if you have the ability to direct fire a separate kettle, try out some decocting. Stick with the same temperatures and times as the temperature mash schedule, but be prepared to get messy and have a really long brew day. By default, you’ll end up holding your main mash for longer at each rest, but that will be offset by the enzymes you’re destroying in the decocted portion. Again, experimentation is needed to get the exact profile you want, but that’s kind of the point of homebrewing in the first place.