Since the discovery that grains, yeast, and water can be transformed into delicious beer, humans have been seeking ways to enhance their brewing success. While ancient civilizations in Mesopotamia and Egypt brewed beer from bread and herbs, modern homebrewers have adopted more refined techniques throughout the brewing process, from mashing to fermenting to bottling or kegging.
One of the crucial steps in brewing, the mash, continues to provoke debates as passionate as the heated grains soaked in water that create wort. When brewing beer using all-grain methods, most people use a single infusion mash. However, if you want to impart unique characteristics to your brew, you might consider a more complex mashing technique called decoction mash.
Mashing is the process of soaking crushed malts (grains) in hot water to convert starches into sugars with the help of specialized enzymes.
Single Infusion Mashing
Single infusion mashing is a basic technique where you mix heated water (infusion) with crushed grains. The mixture is then held at a constant temperature, usually between 148°F and 162°F (64°C and 72°C), for a specific period, typically an hour. Afterward, you rinse the mixture with recirculated liquid and additional water to create wort.
Step Infusion Mashing
Step infusion mashing is similar to single infusion mashing but involves resting the mash at different temperatures during various stages. This can be achieved by directly heating the mash or adding heated adjuncts or unmalted grains such as corn, oats, or barley.
Decoction mashing is a type of step mashing where you remove part of the main mash, cook it separately for a designated duration, and then return it to the main mash. The term “decoction” refers to the portion of the mash that is removed. This process takes longer than a single infusion mash but can result in additional flavors, colors, and sugars.
Resting refers to leaving the mash undisturbed for a specific period to develop desired characteristics. For example, a protein rest breaks down protein chains that may cloud the beer, while a saccharification rest converts starches in the grain into fermentable sugars.
Wort is the liquid extracted from malt that contains sugars fermentable by yeast, ultimately resulting in the production of beer.
Why Use a Decoction Mash?
You might wonder, “Why go through the extra time and effort of a decoction mash when I can make fantastic beer with a single infusion mash?” The answer lies in the nature of modern grain.
Scientific insights have provided brewers with valuable knowledge about grains and how to optimize them for brewing. However, for most of human history (since around 3,500 BCE when beer brewing began), people did not understand how to manipulate enzymes. As a result, traditional brewing involved using undermodified grains that were not optimized for the best brewing outcomes.
The decoction mash was developed during a time when maximizing grain potential required multiple boiling processes to extract every fermentable sugar. Brewers in the past, without thermometers, used single, double, or even triple decoction methods.
To create the best wort possible, portions of the mash were removed, boiled separately, and reintroduced to the main mash at four temperature stages. This encouraged the grains to release their contents, resulting in highly fermentable wort.
Theoretically, one could decoct their mash two, three, or even more times. However, the most common methods are triple decoction, double decoction (which omits the acid rest to expedite the process), and single decoction (a shortcut for reaping the benefits of decoction without an extended brewing day).