Homebrew malt myths die hard. This is especially true for myths that may have a grain of truth to them. (Get it, a grain of truth?) Likewise, myths that seem to be confirmed by casual observation can be hard to debunk. Case in point — black malt (sometimes called black patent malt). This very dark malt has been described as lending an aggressively burnt taste to beers that contain it. Sometimes the adjectives “sharp” and “acrid” are used, and less commonly you will even see it described as ashy. Sources that describe black malt in that manner frequently urge brewers to minimize its use, or to use debittered (or dehisked) black malt in its place. Debittered black malt is black malt that has had the husks removed. As the name implies, it adds less roast “bitterness” to beers brewed with it.
This description of black malt is a mishmash of truths and falsehoods, and perhaps for this reason many homebrewers still cling to this poor description. Let’s start with what’s wrong and then describe the malt as it really is.
Roasted, Not Burnt
Black malt is highly roasted, but it is not burnt. Roasting and burning are two different processes, producing different flavors and aromas. Roasting involves browning food over high heat. Burning refers to the combustion of a material. Roasting produces Maillard products and caramelizes sugars, if the correct precursors are present. Burning can produce soot or ash and carbon monoxide, along with heat and smoke, depending on what is being burned and under what conditions.
Black malt should never lend a burnt or ashy flavor to beer — nor should it be acrid, an adjective most frequently used to describe the smell of smoke — because black malt does not combust when it is produced. Black malt is made from pale malt that is roasted at 221–233 °C (420–450 °F) for up to four hours. The temperature must be monitored closely as the malt can catch fire if it climbs above this. If a batch of black malt did catch fire in the kiln, it would not be sold to brewers.
So what’s a better description of black malt? It depends on how much you use. In relatively small amounts — a few ounces in 5.0 gallons (19 L) of beer — black malt adds a fair amount of color, almost no aroma, and a fairly smooth, roasty flavor with a little roast “bitterness.” You can confirm that black malt has little aroma by smelling a handful of it next to a handful of roasted barley or chocolate malt. The relatively low level of aroma is a consequence of how the malt is roasted. By the end of the process, most of the aromatic compounds have left the malt and are vented from the kiln. To confirm the flavor of black malt, you’ll have to brew with it. In part, the mellow flavor of small amounts of black malt is a result of the lack of a strong aroma.
In higher amounts — for example, if black malt is used as the only dark grain in a porter or stout — black malt has a full, roasted flavor. As with any very dark grain, it can also lend a bit of astringency that is sometimes perceived as bitterness. (Additionally, if your water chemistry is not suited for brewing a dark beer, black malt — as with any dark grain — can drive your mash pH too low. If this carries through and your beer pH is too low, the beer may taste slightly tart and the dark grain character will be “thin.”) So, in large enough doses, black malt can lend an aggressive or sharp flavor to beer. However, this is not the same as burnt, and you will not smell an acrid aroma when using it.
Tomorrow, tips on using black malt.