“Every Act of Creation is First an Act of Destruction”
Lately, I’ve been speaking with my roasting students in the big-picture mode about their superpowers. Roasting is often spoken of in esoteric chemical terms or couched in industry-specific language that can sometimes alienate newcomers. To wit, the old SCAA flavor wheel was used to split certain aromatic compounds into three categories labeled “enzymatic,” “sugar browning,” and “dry distillation.” While fancy and scientific-sounding, I’m not confident this language really resonates with new roasters and tasters.
The first thing most new roasters want to know is how to make great tasting coffee, and I’m confident you don’t have to have a deep knowledge of the science or an experienced cupper’s lexicon to be a decent roaster.
So, I’ve been talking about the powers of realization, creation, and destruction in the context of a coffee’s flavor, to help folks new to the craft get a handle on what they can and can’t do as good machine operators seeking to develop flavor in coffee.
Green coffee comes to the roaster full of potential. Locked up inside the unroasted coffee are hundreds of aromatic compounds, waiting to be expressed.
Those aromas are the result of a wide array of variables, from the soil and plant type, ripeness of the coffee, fermentation and processing methods, storage and handling practices, and much more. Ultimately, green coffee carries with it a story of place, time, and process, showcasing the producers’ methods and hard work.
That story unfolds in the skilled hands of a roaster, using heat, time, airflow, and many other factors. The roaster isn’t imbuing the coffee with those flavors; instead, they are expressing (or suppressing) them, to one degree or another, particularly as the coffee progresses through the earliest stages of roasting.
If you look at that “enzymatic” section of the old flavor wheel, it contains subcategories of floral, fruity, and herbal. These are the kinds of flavors in coffee imparted by place and process. You can’t roast berry notes into a coffee… they have to be inherent to the green coffee character, imbued by factors like plant type, fermentation and drying techniques, etc.
The roasters’ work, when it comes to these flavors then, is about realization – shining a light on characteristics that are hiding, buried deep within the green coffee’s chemical composition.
Generally, lighter roasting styles (perhaps 45-90 seconds after the first crack) tend to showcase these flavors most easily. One actualization technique might simply be to end roasts with short development times and low-end temperatures.
However, there are more nuanced approaches that students of the craft may employ to enhance these flavors: by studying the green coffee, measuring factors such as moisture and density, and dialing sections of the roast prior to the first crack, the roaster can highlight or mute some of these characteristics. The operator can’t create or destroy these flavors, per se, during the early stages of roasting, but they can shape them, highlighting or shadowing aspects like acidity, sweetness, and body in addition to the nuanced characteristics of certain fruit and floral notes.
In other ways, however, the “realization” technique of roasting is about the roaster – the craftsperson and the machine – getting out of the way and “letting the coffee speak for itself.”
What is created in roasting? If we allow ourselves a little bit of scientific leeway and speak mostly about flavors, some of the coffee’s primary, essential flavors are the result of specific choices the roaster makes in terms of time, temperature, and color.
Namely: grainy, nutty, caramelly, and chocolatey flavors are generally roast-style driven. These flavors are layered on top of the inherent tastes driven by terroir and technique. They also account for very specific types of sweetness in the final product, driven by the Maillard Reaction and Caramelization (aka Sugar Browning).
How deeply a roaster allows coffee to dip into development beyond the first crack, and even the early moments of the second crack, largely determines the baseline characteristics of that coffee. While roasts cut off too short may exude bready or cereal like flavors, and coffees roasted light but too fast (scorched) might taste vaguely toasty or like roasted nuts, coffees gently coaxed into development develop distinctive honey-like and/or caramelly sweetness. With plenty of room for overlap, chocolatey flavors begin to emerge in sequence here as well, perhaps at about a minute after the first crack and well into the second as the roast progresses. Additionally, the development – specifically the length – of Maillard Reactions prior to the first crack can enhance or suppress the viscosity of the final brew.
Each of these characteristics is driven by specific, creative choices at the hands of a roaster. Haphazard roasting may result in obfuscated flavor profiles, but informed decisions about the length of a roast, and how the coffee develops color and character, indelibly impart a sense of balance and a set of iconic flavors, only made possible by roasting techniques.
That’s the creative space for the coffee roaster, the flourish of final color and caramelization.
Technically speaking, roasting is pretty destructive. Moisture heats up and eventually leaves as steam. Volatile compounds including aromas and most acids start burning off very early. Sugars get blown up, rearranged, compressed, and expanded. It’s a violent mess.
But the acts of destruction resulting from choices the roaster makes are those which take place in later stages, when we begin the process of pyrolysis – the degradation of compounds in the presence of heat. Pyrolysis technically begins during caramelization, but we really notice it taking over in terms of flavor and roasting process at around the beginning of the second crack.
Coffees taken to second crack and beyond begin to obscure the flavors of realization – inherent terroir and fermentation flavors – by burning them away. We’re left with some of the sweetness of the creation stage (the browned sugars) but the flavors of smoke, char, and spice tend to overwhelm the palate with sensations of bitterness. Bitterness can be mitigated in dark roasts, using a variety of techniques including airflow management and careful heat application.
Chemically speaking, while it’s true that most compounds are degrading or even being roasted away as we roast darker, there are a few late-roast peaks in certain elements that impact flavor. Acetic acid, like that found in vinegar, does not degrade as citric acid does in the presence of heat. It will stick around much later into roasting, such that coffees with naturally higher percentages of this flavor should be roasted carefully, particularly when taken to darker levels. Also, while chlorogenic acid does indeed degrade in roasting, it decomposes into caffeic and quinic acids, which are bitter in flavor. So in some ways, destruction is an act of creation… at least when it comes to making coffee more bitter and smokey.
There’s nothing wrong with roasting dark, both creating and destroying flavors, but it’s worth acknowledging that darker styles of roasting tend to smudge out the more nuanced, delicate flavors highlighted by lighter roasts. Flavors of terroir and caramelization may still be present in darker roasts, but they take a back seat to the flavors of roasting style and process. One could also argue conversely that bolder, roast-driven flavors are never “realized” by lighter roasting styles. Neither is right or wrong, per se. But neither choice should be made without motivation – specifically, well-informed acts of realization, creation, and destruction.