Beer is often divided between sweet and bitter, but that’s an oversimplification. Just as hops offer far more than mere bitterness, malt complexity goes well beyond sweetness. Brewers fine-tune the flavor profile of a beer by selecting the right set of malts, such as crystal malts, Munich malt, or melanoidin malt. These rely on differences in the malting process to affect the character that ends up in the beer, but the brewing process itself can have just as big an impact. In fact, recipes for the most intensely malty styles—think of a fine English barleywine or German doppelbock—may call for kettle caramelization to provide a rich celebration of malt character that can include notes of toffee, caramel, nuttiness, toast, or butterscotch.
Getting Your Malt On
The basic idea of kettle caramelization is to extend the boil step of the brewing process. Typically, this is accomplished by boiling for an extra hour or more, but another approach is to pull a portion of the wort and vigorously boil that down to a much smaller volume. In either case, we’re not actually caramelizing sugar; instead we’re taking advantage of a chemical transformation known as a Maillard reaction. This is the same chemical process that gives baked breads their golden crust or seared meat its distinctive browning.
Where caramelization involves the oxidation of sugar, Maillard reactions occur between amino acids and reducing sugars. As a result, the sugars are transformed to yield melanoidins and other Maillard products that contribute darker color, thicker body, and the flavors of malt complexity.