What is a dark roast?

A dark roast enters second crack or goes beyond it, bean temp between 225 and 245 °C, Agtron 35-60, with oils clearly visible on the bean surface. Sub-grades include Full City+, French (late 2C), and Italian (past 2C). The cup veers toward dark chocolate, smoke and liquorice, with pronounced bitterness, thick body and very low acidity. It is the signature of Neapolitan espresso and many industrial blends.

Past first crack, a dark-roast profile keeps pyrolysing the bean structure. Between 219 and 224 °C sits Full City+, still manageable for specialty work. From 225 °C on, second crack opens up: a drier, more metallic snap, less intense than the first, caused by cell walls hardened by partial carbonisation finally fracturing. Oils migrate to the surface and beans look glossy. At 230-235 °C: French Roast. At 240-245 °C: Italian / Neapolitan Roast. Beyond 250 °C you are simply burning — the cup becomes acrid and one-dimensional.

Chemistry-wise, pyrolysis now destroys more than it builds. Sugars that did not caramelise char into bitter derivatives (heavy furfurals, 2-furanmethanethiol at high concentration). Origin acidity drops 70 to 90 %. Caffeine stays nearly stable (it sublimes above 178 °C but total roast loss is under 10 %). Body thickens as soluble lipids migrate to the surface and load the cup. Lesser-known fact: dark roasts lose 20 to 22 % of dry mass and up to 18 % of volume, versus only 13-15 % for a light roast — which is why 1 kg of dark beans takes noticeably more scoops.

Italian tradition (Naples, Turin) shaped this degree from the 19th century onwards, first to mask green-Robusta defects in cheap blends, then by cultural taste — the Italian love of bold espresso with tiger crema and a chocolate-hazelnut finish. Many European supermarkets still sell beans and ground coffees in dark roast, often to smooth out the quality of average commercial green coffee. In Belgium, the daily family tradition of filter coffee leans toward medium-dark, softer than strict Italian but fuller than a specialty medium — a logical partner for a speculoos, a cuberdon or a slice of cramique.

Dark roast at a glance

Understanding What the Heat Actually Does

The case for dark roasting is more sophisticated than its critics often acknowledge. When a coffee is taken to a full dark roast — typically above 220 °C bean temperature, into or past second crack — a series of chemical transformations occur that fundamentally change the nature of the drink. The chlorogenic acids that dominate green coffee's chemical profile and contribute to much of its perceived bitterness and acidity are largely degraded by dark roasting temperatures, producing compounds called lactones that have bitter but less harsh characteristics. The Maillard and caramelisation reactions that began at medium roast levels continue and deepen, building the carbon compounds that give dark roast its characteristic smoky, bittersweet, and chocolate-forward profile. These are real flavours that some consumers genuinely prefer and that have a long culinary tradition — in Italy, where espresso culture was codified, a dark roast standard was established not from ignorance of alternatives but from a deliberate aesthetic preference for intense, bittersweet beverages.

Where the criticism of dark roasting becomes legitimate is when it is applied to high-quality green coffee as a means of masking rather than developing: when a producer has invested in exceptional terroir, careful processing, and precise drying, and a roaster then applies temperatures that obliterate the distinctive regional acid structure and aromatic complexity in favour of a uniform roasted character available from any origin. This is a genuine quality loss, not merely an aesthetic difference. Light and medium roasting of the same coffee would reveal the origin-specific compounds that justify the premium paid for specialty green coffee. Dark roasting of commodity-grade green coffee is, by contrast, a legitimate and sensible approach: the roast is doing real work, covering defects and producing a palatable beverage from raw material that would not be enjoyable at lighter development levels.

Practical Recommendations

If you are a dark roast drinker curious about what you might be missing, the most useful experiment is a medium-light pour-over from the same origin that your usual dark roast blend is sourced from. Ethiopia and Colombia are the most accessible starting points: a medium-light Ethiopian Yirgacheffe brewed at 94 °C through a paper filter delivers floral and citrus character that is genuinely extraordinary and unlike anything a dark roast can produce. If you try it and prefer your dark roast, that is a legitimate preference — the specialty world's tendency to treat light roasting as inherently superior ignores the real pleasure that a well-made dark espresso provides. If the medium-light astonishes you, you have discovered a new dimension of the beverage. Either outcome is valid; the point is informed choice rather than habitual default.