Making coffee taste good is a lot of work. Quality-focused farmers meticulously hand pick their coffee cherries, and then process these with great care before sending their coffee abroad to be roasted. Once it has arrived at the roaster, however, there are still many opportunities for error. Whether due to over- or underroasting, an inexperienced roaster can easily undo all of the hard work that has gone into making a coffee taste good before it has even arrived at a roasting facility. Because maintaining quality is so important, and roasting is so difficult, good roasters will have generally devoted years to honing their craft, and aspiring coffee roasters will undertake years-long apprenticeships in order to learn and master the intricacies of the profession.
So what specifically is the job of a roaster, and why is roasting so difficult? If you’ll allow me to be a bit esoteric for a moment, a roaster’s job is to allow the coffee to speak for itself. By this I mean that a quality-focused roaster should seek to highlight rather than mask a coffee’s intrinsic qualities with the roasting process. Coffee, like all agricultural products, is heavily influenced by the environment in which it was grown. It is capable of yielding a vast array of flavors depending on the climate and composition of the soil in which it was grown, and a roaster should seek to highlight these naturally-occurring flavors rather than impart the flavor of the roast. As a coffee is roasted, its sugars react with its proteins and produce a Maillard reaction, which lends it a natural sweetness and recognizable brown color. Additionally, a series of chemical reactions occur which produce the aromatic compounds that can allow a coffee to taste like anything from cashews to pears to blueberries. Roast a coffee too lightly and its acids will not sufficiently degenerate, resulting in a cup whose acidity overpowers any other flavor. Roast a coffee too darkly, however, and its sugars begin to carbonize rather than caramelize, resulting in a cup that tastes like roast and nothing else.
A mindful roaster is looking to find the sweet spot in between these two extremes which will produce a cup that’s naturally sweet and expresses the flavors of the coffee’s terroir. This makes the task at hand sound simpler than it is, though. One major complicating factor is the fact that different coffees might need to be roasted in different ways, and it’s not just a matter of roasting a coffee for, say, 9 minutes rather than 12. Modern day roasting machines allow complete control over the temperature at which coffee is roasted, and an experienced roaster is going to manipulate these temperature variations in order to yield a desired set of flavors. One coffee may want to start out at a low temperature and spike at the end of the process, whereas another coffee might taste best if it maintains a fairly modest upward rise in temperature. As you can see, there are near limitless possibilities in how temperature can be manipulated over the course of a coffee’s roasting cycle, and the goal of a roaster is to zero in on the exact recipe for each coffee. This requires a lot of trial and error, and a team of people tasting the results of each roast and comparing notes. When this team finally lands on the proper roast recipe for a given coffee, though, the results can be extraordinary. Tasting a coffee and realizing your efforts have allowed it to express such unique and exciting flavors is a singularly gratifying experience.