The saying goes “there’s more than one way to skin a cat” and this also applies to mashing your grains. I will run you through the basic mash schedules that home brewers can do and what the benefits of each one are.
Mashing is a process to convert the starches in malted grains into fermentable sugars. Different types of mashing vary in complexity and laboriousness, obviously they aren’t just to create extra effort and hassle, they do have purpose and benefits which we will look at now.
Single/Basic Infusion Mash
The infusion mash is the simplest of the three types of mashing I’m talking about here. The infusion mash is so called because you are basically infusing all the grain in water at a single temperature, usually for around an hour. The only thing you need to make sure of is that you maintain a constant temperature to allow the naturally occurring enzymes in the malt convert starches to sugars.
The obvious benefits of this mash is it’s simplicity and ease. You don’t need to constantly tend to the mash and the process is usually the best option for the vast majority of beers you brew. You won’t be able to brew certain beers though. Those that use high proportions of adjuncts or unmalted grains like wheat. Although these make up very few of the vast varities of beers you can make these types of beers you will need to alter the temperature of the mash multiple times using what is called, step mashing.
Step Mashing or Multistep Mashing
Slightly more laborious, depending on your equipment than a single infusion mash is the step mash. Using this type of mash you raise the temperature to certain targets and rest at those temperatures i.e 50°C, 60°C, 70°C.
The brewer calculates these rest temperatures according to the type of beer and ingredients, each rest promotes the activity of certain enzymes. The protein rest for example favours proteolytic enzymes that break down larger protein molecules in the beer, promotes head retention and prevents chill haze.
The thing about step mashing is you need a heat source through the mash to raise the temperature up to each rest, unless you have a way to directly heat your mash tun then it can be a pain to do a step mash. If you use a cool box mash tun then you would need to use a thick mash and add boiling water to raise the temperature, this can be tricky and cumbersome. Step mashes are easier in pots that can be directly heated, whilst stirring the grains to prevent scorching.
As I mentioned before though in some cases a step mash will be required for example when brewing a wheat beer where there aren’t enough enzymes to convert the malt to make fermentables.
A decoction mash is the most laborious and is similar in some respects to a step mash. It involves taking portions of the mash (usually a quarter or third) heating this up to boiling whilst stirring and then adding it back to the main mash. This process of boiling sections of the mash is repeated two or three times until the final mash temperature is reached.
This might seem a peculiar way to go about things, but this mashing process came about because a few hundred years ago metal pots big enough to mash in weren’t available. By heating part of the mash large quantities of beer could be made using the available equipment.
As the decoctions are boiled and added back to the mash the overall temperature rises up in steps that simulate those of a step mash giving you rests that allow enzymes to work.
As you can imagine this is a very labour intensive method of mashing and takes the longest time. However many people say that decoction mashing will add a more complex malt profile to your home brew and it’s qualities can’t be achieved in any other way.