Myths abound in the coffee industry, but few are more off the mark than the ones around the quality of dark roasted coffee.
Roast profile, roast level, roast degree – whatever you call it, the concept is the same. The longer you roast coffee, the darker the beans become, from light brown all the way to black.
The moment green coffee beans enter the roasting drum, they are exposed to high temperatures (typically between 350-450°F), which triggers a number of chemical reactions. These include the following:
- Drying: As the beans are initially heated, they lose moisture and become less dense.
- Maillard reaction: The heat of the drum causes a chemical reaction between the amino acids and reducing sugars present in the beans, which gives coffee many of its characteristic flavors and aromas.
- Caramelization: This is a form of pyrolysis (chemical decomposition as a result of heat). Up until this stage, the beans have been absorbing heat energy and building up internal pressure. The sugars in the beans start caramelizing, which browns the sugar and releases aromatic and acidic compounds. During roasting, most of the sucrose is converted to caramelized compounds.
- First crack: At this stage, the beans release built-up energy, steam, and carbon dioxide (CO2) from their core. They spontaneously expand, expel chaff, and start giving off smoke. They emit a cracking sound from within the drum, not unlike the sound of corn kernels popping.
- Second crack: As the roast continues, the beans will make a second cracking sound. When a second crack occurs (typically around 435°F) the oils within the coffee beans start to migrate to the surface. The roasting smoke also becomes darker and more pungent. This is characteristic of dark roast profiles.
Among these stages of the roast, caramelization and the development of oils contribute significantly to the darkening color of the beans.
During the first few minutes of roasting, degradation of chlorophyll causes beans to change color from green to yellow. Then, as the roast progresses, the beans go from yellow to tan to light brown due to Maillard reactions.
But it’s not until the beans approach “first crack” that the brown color deepens due to caramelization. As this happens, the appearance of oils on the exterior of the beans also contribute to their darkening color.
Is dark roast coffee bad quality?
Having learned why coffee varies in its color, you can now see why the myth about dark roasted coffee being “bad quality” frustrates roasters.
The science behind caramelization and the migration of oils to the exterior of the beans occurs for all coffees, whether from Colombia, Brazil, Vietnam, or Ethiopia. Essentially, it means the fact of being “dark roasted” does not depend on the inherent quality of the coffee itself – it is the choice of roasters and consumer preferences.
The counter argument to this put forward by some is that roasters make a conscious decision to roast coffee darker because it hides the “inferior” characteristics of the beans. But this is also misguided.
Dark roasted coffee is often chosen as it is better suited to espresso brewing techniques.
This is because the longer coffee is roasted, the more soluble it becomes.
Solubility is vital for faster brewing methods, such as with a Moka pot or espresso machine, as the hot water has less time in contact with the ground coffee – and, therefore, it has less time to extract all the flavor from its compounds.
Although light roasted coffee can be used to make espresso (just as dark roasted beans can be used to make filter coffee), coffee that has been roasted for longer tends to yield more flavor in the cup.
In addition, dark roasted coffee is key for producing crema (the thin layer of foam typically found on top of an espresso or café cubano). Crema is produced when hot water at high pressure comes into contact with the emulsified oils from the coffee.
As discussed, dark roasted coffees tend to have more oily surfaces, which helps produce a thick, rich crema, which gives espresso its characteristic texture, body, and aesthetic.
Does dark roast coffee pair well with milk?
Milk and coffee is like a meeting of two great minds. However, there’s little doubt that some coffees work better than others as a base.
In general, dark roasts tend to complement the sweetness and creaminess of the milk better than light roasts. It creates a smooth and well-balanced taste, while enhancing a number of the flavors, such as chocolatey or nutty notes.
Dark roasts also work particularly well when making café cubano (or Cuban coffee).
The strong, bold flavor of the dark roast complements the sweetness of the sugar that is traditionally added to the coffee, creating a nice balanced drink. It also produces a thick, rich body which is perfect for the high-pressure brewing process of café cubano.
Overall, drinking light, medium, or dark roasted coffee isn’t what matters. The most important thing is to find coffee that has been well sourced and roasted. A quality coffee will always be quality regardless of how you like to prepare it, whether in a Moka pot, an AeroPress, or as a pour-over.
At Mayorga Coffee, we have a range of delicious organic dark roasted coffees that pair well with milk, sugar, or by themselves.
Our Café Cubano Roast is one of our most popular dark roast coffees. It is a full-bodied coffee with hints of vanilla and a sweet, syrupy smokiness that pairs well with sugar to produce a smooth, bold finish.
