Two types of enzymes
There are two enzymes that make sugar from starch: alpha-amylase and beta-amylase. Both of these enzymes are important to the brewing process, but they operate at slightly different temperatures. Alpha-amylase operates at high mash temperatures, from 153-156°F. Beta-amylase operates at lower temperatures, from 143-152°F.
When you are brewing your beer, it is important to be aware of your mash temperatures. Whether you activate alpha- or beta-amylase makes a difference in the type of beer you end up with. This is because of how each of the enzymes breaks down starch molecules. Alpha-amylase chops the molecules into complex sugars, while beta-amylase chops them into simple sugars, which are easily digestible by yeast.
Of course, you want both enzymes activated at some point in the process but depending on the type of stout you are brewing, you will want one or the other to be more active in your mash.
So what temperature should my mash be?
For a dryer beer, such as an Irish stout, your mash should be at a lower temperature, somewhere around 148-150°F. This activates beta-amylase, which ensures that all of the fermentable sugars are available for the yeast to digest.
For a sweeter beer, such as a sweet stout or an imperial stout, you need residual sugars. This is particularly important if you plan on aging the stout in a barrel. This requires higher mash temperature, from 152-154°F, to activate the alpha-amylase that will break the starch down into complex sugars that the yeast won’t be able to digest.
Adding in your own enzymes
Our brewmaster Mark Stevens says that Attenuzyme Pro is the way to go:
“Attenuzyme Pro can help you achieve different ratios of maltose to glucose depending on what you are looking to achieve with your recipes. Attenuzyme Pro has a wide dose range and when dosed at lower doses can provide you with a moderate maltose to glucose wort and when dosing at higher doses, can give you a much higher glucose wort.”