We talk about beer brewed according to "ancient craft" methods, but you want a specific example of an ancient method. Triple Decoction Mashing. And how exciting that it is still practiced by Göller Brewery!
If you aren't sure exactly what decoction mashing is, you'll want to read on. "Decoction mashing" in brewers' lingo means separating part of the mash, boiling that part, then returning it the main batch. This action was very important to ancient brewers because, not having thermometers, they still needed to get the right temperatures for mashing. They could achieve the necessary temperatures by this Triple Decoction.
Nowadays decoction is not strictly necessary for a successful mashing because of superior technology and improved malts. Few brewers, therefore, still use decoction. However, many agree that this old style decoction method imparts a special flavor that is found in some craft German beer, a robust maltiness that can't be replicated by modern methods of infusion mashing.
Let's describe in more detail what is happening with mashing.
The malt contains enzymes that are needed to turn starches in the barley into maltose, a sugar needed for fermentation. There are basically three types of enzymes that do the job, but each type gets activated at a different temperature. Accordingly, the mash needs to be allowed to rest at three different temperatures of roughly 130°F, 150°F, and 170°F, the temperatures at which the enzymes are activated. Ancient brewers discovered that by removing 1/3 of the liquid mash, boiling it, then adding it back into the mash, they could bring the mash to these three stages as needed. They didn't know what was happening scientifically, but they knew it worked.
Nowadays brewers control the temperatures by direct-heated mash tuns. But is anything lost when you do not decoct? Many craft brewers say "yes." Different things happen when you boil and re-add it to the mash, such as increased Maillard Reactions that add maltier flavors to the beer. There is a lot of debate over this topic in the brewer's world, but Göller Brewery believes that they make a better beer by using the traditional method.
We at Ancient Craft Imports agree that that this ancient method imparts a special characteristic that makes our favorite beer unique.