Coffee Basics: How do you roast coffee?

As you might imagine, at Counter Culture Coffee, we talk about coffee a lot. We’re passionate and sometimes use industry terms to convey complicated concepts. That said, we also want to make sure that we talk about coffee in a way that anyone can understand. To that end, we’ve started a new series that aims to shed light on coffee subjects in an accessible way. The fourth topic for our Coffee Basics series is about roasting coffee. The image above shows Counter Culture founder Brett Smith and Fred Houk with one of their first roasters. Coffee roasting looms large in the imagination of most coffee enthusiasts and for good reason: Roasters preside over transformation of an unexceptional little seed into the complex, diverse, and delicious “beans” that we grind, brew, and enjoy. Even for very experienced roasters who may have been in the trade for years, the transformation that coffee undergoes in the roaster never stops being a source of fascination and excitement—especially if they are lucky enough to work with really great green coffee, as we do here at Counter Culture. What is coffee roasting? The process through which green coffee beans transform into roasted beans used to brew coffee is fairly simple, but also quite easy to mess up. When roasting coffee, you’re trying to bring the coffee to a specific internal temperature or level of “development” through the careful application of heat and close observation.

Green coffee before roasting

Heat not only caramelizes sugars and browns the coffee during the roasting process, it also catalyzes a host of other chemical and physical changes that, when properly executed, create a product that is both familiar and surprising. Most basically, roasting is the application of different types of heat to create chemical and physical changes in green coffee. There are three basic types of heat: Conduction (contact heat) – like you get from a frying pan Convection (hot air) – like a blow dryer or popcorn popper Radiance (radiation) – like the heat transmitted through space from our sun The machines at Counter Culture use all three means of heat conveyance in varying proportions: e.g. our Probat roasters (pictured below) are heavier on conduction while our Loring roaster is heavier on convection. How do you roast coffee? Here at Counter Culture, we adhere to a simple formula: great green coffee + the right amount of heat + the right amount of time = great roasted coffee. There are a range of different styles and approaches to roasting. Just as you can cook a steak in a hot pan, on a grill, in the broiler, in the oven, or even sous vide, likewise, different roasting “machines” can range from a cast iron skillet to fully automated, stainless steel convection ovens. (We don’t think anyone is trying sous vide yet, but it could be fertile ground for exploration.) Regardless of approach, the cook/roaster tries to judge the product’s progress and how “done” the beans are based on an assortment of visual, smell, and temperature queues.

Our roasters use a combination of data and sensory testing to determine roasts

Counter Culture roasts on big industrial machines that tumble the beans inside a heated drum. All of our machines are run manually, meaning there is a human manipulating each batch and determining how the roast runs. Our machines offer fairly precise information on how much heat is being introduced to the roasting process and how the coffee is reacting, but the dynamics in each machine vary tremendously. So, while precision and consistency are aided by the sophistication of our equipment, our success is heavily dependent upon the experience of the roaster—meaning how well-versed they are at interpreting queues and how familiar they are with the equipment they are working on. How do you differentiate between roast levels? Lighter roast profiles tend to emphasize the unique characteristics of the coffee, while darker roasts tend to emphasize more roast character. We try to offer a broad range of profiles on our menu to suit different tastes. Each coffee has a specific roast-level target, and we evaluate the roast level of every batch to ensure consistency using a light reflectometer called an Agtron machine. The Agtron bounces ultraviolet light off of a sample of coffee and back to a sensor to analyze the color of ground or whole bean coffee, then outputs a number that represents the degree of roast. The lower the number, the darker the roast. For example, our darkest roasts have an Agtron score of 48, medium roasts between 58–65, and light roasts anywhere above 70. You can find our Agtron numbers (like the one below) for all of our coffees on the product pages. When looking at our year-round coffees, you can see that both Fast Forward and Apollo fall on the lighter end of the spectrum, at 72, while Big Trouble, with a score of 63 is about medium, and Forty-Six, at 52, is on the darker end.

The gradient of beans shown here represents roast levels per minute from one to sixteen

We also avoid using vague roast level descriptors like “blonde roast,” “full city,” or “Italian roast,” and instead try to help our customers find the coffee that best suits them by offering specific tasting notes associated with each coffee. For instance, “dark chocolate, smokey, full-bodied” for Forty-Six, or “citrus, floral, silky” for Apollo. At the end of the day, our goal at Counter Culture is to always create balanced, complex coffee no matter what the roast.