Brewing with Dark Grains

Dark grains are an important ingredient in brewing many styles of beer. Grains that can be considered to be the “classic dark grains” include chocolate barley, black patent barley and unmalted, roasted barley. If one is so minded, it is also probably OK to include in the category of dark grains some of the very dark, roasted specialty grains such as chocolate wheat and special B.

In order to make dark grains, malt companies expose grains to relatively high temperatures within a roasting kiln for a particular amount of time, which depends upon what is being produced. Exposure to higher temperatures for longer times produces a darker grain. Longer, high-temperature kilning produces darker, more intensely flavored malt. Shorter, lower-temperature kilning produces lighter colored malt with less flavor intensity. Table 1, below, shows how temperature and time affect the color of kilned malt.

Pale malts are dried and kilned rapidly at low temperatures. Pale malts have a more subdued flavor and tend to be higher in the diastatic enzymes α-amalyase and β-amalyase (high temperatures deactivate these enzymes). More colorful and flavorful malts can be made using a two-step kilning process consisting of an initial low-temperature kilning followed by a higher temperature cure. The low-temperature step allows the formation of low-molecular-weight sugars and amino acids and the higher-temperature step allows the compounds to react via the Maillard reaction. During the Maillard reaction, compounds are formed that have very intense flavor and color characteristics. These flavor and color compounds include brown and flavorful melanoidins, volatile aldehydes such as furfural, and other compounds such as pyrazines, thiophenes, pyrroles and furans. If the malt is kilned at a high-enough temperature for a long-enough time, roasted malts such as chocolate malt and black patent malt are produced. These malts contain the highest concentrations of the flavor, and color compounds and represent the most extreme results of the kilning process.

Exposure to high temperatures not only develops the dark colors and flavors associated with dark malts, but it also destroys the enzymes contained within the barley. Because dark grains have all been exposed to the relatively high temperatures within the kiln they have no functioning diastatic enzymes. As a result they do not actually need to be mashed. Steeping these malts is sufficient to release their flavor and remaining sugars.
Gordon Strong has talked about the different ways that dark malts can be used for brewing within his book Brewing Better Beer. In his book, Gordon describes dark grains as somewhat analogous to roasted coffee. As with coffee, time and temperature play critical roles in the taste of a beer brewed using dark grains. The intensity and duration of the exposure of dark grains to heat within the aqueous environment of the brewing process will determine how much flavor is obtained. In general, higher heat for longer periods of time will dictate the degree to which bitter, acrid and acidic flavors are extracted from the grains.

Dark grains such as chocolate malt, black patent malt and roasted barley do not need to be mashed, but brewers often do add dark grains into the mash, possibly because it is simply more convenient to handle all of the grain together. This isn’t necessarily a bad way to do it, but there are other options. The following sections (using information primarily from Gordon Strong’s book) describe the options:

Traditional Mash

In this approach, the dark grains are milled and mashed along with the rest of the grains in the grist. This approach can lead to harsher, more astringent flavors in the finished beer, especially if the water being used is very alkaline, high in bicarbonates, or has a relatively high pH. Using dark grains in a traditional mash exposes the grains to the highest amount of heat for the longest amount of time, and so is most likely to produce a harsher, more astringent character in the finished beer.

Adding at Vorlauf

The vorlauf is the recirculated wort typically drawn at the start of the sparge — usually the first few quarts of runoff for a homebrewer. These first runnings are then recirculated back to the top of the grain bed. Using this approach, the dark grains are not added during the mash, but rather are added at mash-out. The advantage of this method is that it avoids the long hot steep of the mash, and the dark wort from the vorlauf is recirculated through the mash tun again further reducing astringency.


If using an approach of steeping dark grains, the dark grains should be milled separately. It is acceptable to mill the dark grains very finely if desired. A ratio of water to grain of 2 quarts (~2 L) of water to 1 pound (0.45 kg) of grain is a good ratio for steeping. The steeping options to be considered include hot steeping, cold steeping with no boil, and cold steeping with a short boil.

Hot Steeping

Using this method, the dark grains are mixed with 165 °F (74 °C) water and steeped for five minutes. The mixture is then filtered or strained through a coarse filter media. The grain extract can then be added to the wort in the fermenter (not during the wort boil). The grain extract can also be refrigerated for later use if it is not needed for brewing immediately. You can store it for several weeks as long as it is first sanitized within the process, placed in a sanitary container, sealed, and stored cold.

Cold Steeping with No Boil

Using this method, the dark grains are mixed with cold water and allowed to sit at room temperature for a full day. The grain extract can then be added to the wort in the fermenter (not during the wort boil) or refrigerated for later use if is not needed immediately.

Cold Steeping with a Short Boil

Using this method, the dark grains are mixed with cold water and allowed to sit at room temperature for a full day. The grain extract is then added to the brew kettle during the final 5-10 minutes of the boil.

The Bottom Line

According to the information in Brewing Better Beer, tasting results from experiments conducted by the Briess Malting Company indicated that black malt tasted best using the cold steep method, while roasted barley tasted best using either the hot steep or cold steep with a short boil method.

Steeping the grains and avoiding most of the longer, high temperature exposure results in less astringency, less harshness and less acidity. The only downside is that is adds another step in the brewing process.

2) Mosher, Randy, The Brewer’s Companion, Adelphenalia Publications, 1995
3) Goldhammer, Ted, The Brewer’s Handbook, KVP Publishers, 1999
4) Strong, Gordon, Brewing Better Beer, Brewers Publications, 2011

Table 1: Effect of Kilning Temperature and Time on Formation of Color


Issue: October 2014