Recently, a reader of Craft Beer & Brewing Magazine asked us the following question:
I have a few older brewing books that recommend multistep mashes. What is the purpose of doing extra steps in the mash?
Multistep mashes are not commonly done anymore, and most all-grain brewers now use a single step, called the saccharification step, with the main conversion taking place in roughly the 148–156°F (64–69°C) temperature range. The reality is that most modern barley malts simply don’t need the additional steps.
Multistep mashes, including steps such as acid rest and protein rest, were once used to help lower the mash pH and create the enzymes needed to help break down sugars in the malt during the main conversion step. Before the development of modern malt science, malted barley, including base malts, often were not fully modified, which means that they lacked sufficient enzymes to convert the malt. These “undermodified” malts often required additional lower-temperature mash steps that would develop the enzymes needed for mashing.
Malting science has come a long way in the past 30 to 40 years, so virtually all malts you can purchase today are highly modified, meaning they have more than enough enzymes needed for the conversion step. In fact, you need to specifically seek out an undermodified malt if you want one for some reason.
You can find out the enzyme content by looking up the “diastatic power” of your malt on the malt’s data sheet. Most of the enzymes come from your base malt, and you only need to be concerned about additional steps if you are using a very large portion of non- barley or undermodified base malt in your beer. For the vast majority of barley-based beers, a single-step mash is sufficient.