Multi-step mashing

Multi-step mashing

1 2 months ago

Although multi-step mashing is not so widespread in many homebrewing cultures (the main reason being that it is mostly used for unmodified or undermodified malts), it gives a great opportunity to play and experiment with activating and denaturing the enzymes of the malt.
Of course, these are not only for the sake of scientific experimentation - the different uses of these mashing steps or “rests” can and will help you to manipulate how dry or sweet, velvety or astringent your wort will become.
The good news is that it means you can easily customize your wort depending on what kind of beer you’re looking for. The not-so-good news is that’s the reason why there are no exact rules or laws of using this method.
But how does it affect our brew? Without going into details, enzymes produced in the malt during malting are active on different temperatures, therefore realize their effect (breaking down different components of the mash) separately. As they affect the mash’s composition, in the long run they affect the quality of the finished wort.

What is sure, that there are three main types of rests that’s used during a brewing session:

  • Acid rest
  • Protein rest
  • Starch conversion / saccharification rest

The acid rest is a less popular phase. Its main aim is to lower the pH value of the wort, which can be realized only after at least an hour of mashing on 35-45°C.

What is more important, is the protein rest. During this phase, two types of enzymes (peptidase and proteinase) start to break off longer protein chains into moderate, then smaller ones. However, this situation needs to be addressed - while big proteins can lead to haze and instability, medium length chains helps the beer’s body and foam retention. This situation can be solved by adjusting the temperatures - the medium length chains are broken up most efficiently between 45-53°C, while longer chains are broken up by proteinase between 55-58°C. A 15-30 minutes of mashing on the latter temperatures can help avoiding haze in your beer.

The third important phase is starch conversion or saccharification rest. This rest is required for all batches, since enzymes break down starch in this phase into sugars (which later will be fermented into CO2 and alcohol). Since starch conversion is done by two different enzymes, this phase is usually done between 60-72°C.
Both beta- and alpha-amylase break down starch, but while the former starts this process from the ends of the starch-chains, the latter breaks them down in its junctions. Two basic processes can help break down the starch:

  • Since beta-amylase is more active on a lower temperature (60-67°C), let it first attack the starch chains’ ends, to leave the junctions “open” for the alpha-amylase, which will be activated on a higher temperature (66-72°C).
  • In another method, the alpha-amylase break down starch-chains, resulting in many more smaller chains - all of which can be attacked on both ends by beta-amylase. This is done in parallel, which is preferred in most single-infusion mashes, on 66-67°C, typically for 60 minutes.

Of course the wort can be produced with other methods - with a long, long rest (60-120 minutes) for the beta-amylase to work itself (between 60-63°C), creating a highly fermentable wort. Or you can produce a more full-bodied, sweeter, very thick wort after 20 minutes of mashing on the high-end of the alpha-amylase range (68-72°C).
These informations are, of course mostly guidings - choosing the optimal mashing steps for your recipes needs every information about what malt you’ll use, what type of beer do you wish to brew, etc. But if you have not yet used multi-step mashing processes, it might help you on how to use them regarding your wort.

Remember: the road to the perfect beer leads through experimenting, so always write down all steps and information about your brew - in this way, you can always adjust every single part of the process, or repeat it if you’ve found what you were looking for.

Happy brewing!