Decoction mashing can seem like an impassable mountain on your hero’s journey as a homebrewer. It offers the promise of deeper malt character, but the extra time and work are too daunting for some. Brewing masters contribute to the mythology as they debate using single, double, or even triple decoction schedules.
Decoction Demystified
But don’t believe the hype; decoction mashing is actually fairly simple. All it involves is pulling off a portion of the mash and boiling it for some time before adding it back in. The qualifiers—single, double, triple—refer to how many times the process is repeated within the context of step mashing. A full step mash schedule may include an acid rest at 95─113°F (35─45°C), a protein rest at 131─138°F (55─58°C), saccharification at 142─160°F (61─71°C), and mash out at 168─170°F (75─77°C). Decoctions can be used to heat the mash from one rest to another. Typically a single decoction is used to move from saccharification to mash out, but the extra rounds can be used with additional rests in the schedule.
So why bother? The biggest justification is somewhat outdated. Most malts today are highly modified, but that wasn’t always the case. The full step mash evolved to deal with under-modified malts, and boiling a portion of the grain prepares those malts to be more effectively mashed. Another part of the appeal is that it’s a traditional touchstone that connects modern brewers with their European forebears, and many would claim you can’t make a real German lager without a decoction mash.
Aside from the historical weight, though, there are some practical reasons to try it: decoction mashing adds melanoidins and complex malty character while creating the conditions for a clearer beer. But if you’re not convinced enough to tackle a decoction mash on your next batch, there are some simpler ways you can try to reap some of the benefits.
The Obvious Alternative
Many sources suggest short-circuiting the process: if melanoidins are the secret to malt complexity, then just add some melanoidin malt to the mash. This can add some rich malt character, but it doesn’t really capture the flavor of a decoction mash. In particular, melanoidin malt often skews the balance sweeter, making it harder to get the crisp dry finish of classic European lagers.
Simplified Decoction Variations
There are a few ways to capture decoction magic by integrating boiled grain into your mash. Some might argue that you might as well just do a decoction, but these approaches can streamline the process.
The first option is known as the Schmitz Process, and it’s sort of an inverse decoction mash. Bring the mash up to temperature for starch conversion, say 150°F (66°C), then let the malt settle before you collect as much liquid from the top as possible. Set the liquid aside, holding it at temperature, while bringing the grain to a boil for 15─30 minutes (be sure to stir constantly and keep an eye on your water levels so you don’t accidentally scorch your grains!). Then, cool the grist back down to 150°F (66°C) and stir the liquid back in to continue the mash. The idea is that boiling the grain will break it down and yield malt complexity, and it’s assumed that the liquid contains enough enzymes to convert all the starch.
To me, this seems like extra work, especially the step of cooling the boiled mash, so it’s not much of an alternative. If you try this, aim for a thinner mash to ensure that you’re pulling off enough liquid and enzymes.
Another choice boils decoction down to its simplest elements. Start your mash normally, holding your targeted starch conversion temperature. After about 25 minutes, pull out about 20 percent of the mash and heat it to boiling (again, watching your water levels, and stirring constantly!). This grain will be added after mash out, just before the sparge. The main savings relative to a real decoction is that with this method, you’re not depending on the boiled grist to heat the grain to mash out.
I think the best alternative is Kai Troester’s (@braukaiser) pseudo-decoction. He recommends a thick initial mash, combining half the grain bill with a third of the total mash water. Once this is mixed together, he brings it to a boil for 20─30 minutes (don’t forget to stir and watch those water levels!). Then he mashes in the remaining malt with the rest of the water, aiming for his target saccharification temperature. The second half of the malt bill provides plenty of enzymes to convert all the starches. You get the melanoidin malt character from boiling the grain, but it’s done in a way that doesn’t disrupt the mash with complex operations. The added time is relatively short, too. Next time I’m tempted to do a decoction, I plan to try Kai’s process out.
You shouldn’t be scared of decoction, but if one of these alternatives looks a little easier, then use it as a boost up your brewing mountain.