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.
Many of the flavor differences between malts are due to Maillard reactions that occurred during the kilning process, so kettle caramelization is just another opportunity to add to that mix.
How Much is Too Much?
Malt complexity is generally a good thing, right? So, it’s tempting to make kettle caramelization a regular part of your brewing process. Keep in mind, though, that those stronger malt flavors don’t fit every style and, even in a malt-forward beer, you can end up with too much of a good thing. A relatively positive flavor can become cloying if it’s taken to an extreme, such as in a toffee/caramel dunkel.
Other facets of rich malt flavor may not be all that pleasant if elevated too high in the mix, either. For example, even though diacetyl is usually a fermentation product, it can also be created during Maillard reactions. Small amounts of diacetyl can pleasantly contribute to a malt profile, but it’s very easy to overdo it. Other Maillard products may create flavors similar to soy sauce or even “extract tang.”
The best advice is to reserve kettle caramelization for the right styles and then to dial in the process for each recipe. Good target styles include bock or doppelbock, Scottish wee heavy, old ale, barleywine, imperial stout, and Belgian dark strong ale. Rather than go over the top, try a two-hour boil to see where that gets you. You can always adjust accordingly the next time you brew your recipe. If you’re concentrating a portion of the wort, start by pulling off a half gallon and boiling it down to a quart or so before adding it back to the main boil. Once again, you can always turn up the effect by pulling a larger portion or boiling it down further, or you can pull back if it’s too intense.
Test Drive
If you want to try your hand at brewing some beers that benefit from kettle caramelization, here are a few recipes from the Craft Beer & Brewing Magazine® collection:
Old Haggis
Fonta Flora Brewery’s Appalachian Wild Ale
Scottish Light Ale (60/-)
120/- (120 Schilling) Wee Heavy
And here’s a recipe that uses specialty malts to mimic the kinds of rich Maillard-derived flavors you’d get out of kettle caramelization: