Dark roast
Roasted into or past second crack. Roast-derived bittersweet, smoky or roasted flavours dominate over origin character; body is typically heavier.
In short
A dark roast is coffee roasted until around or beyond second crack. The beans are dark brown to nearly black, lighter in weight, brittle, and often shiny with oil.
At this point the flavours created by roasting dominate: bittersweet, smoky, roasted, like dark chocolate or toasted nuts. Acidity is low and body is heavy. It is the roast that stands up best to milk and sugar, and the easiest to make bitter.
What second crack does to the bean
Widely documented
Second crack comes some time after the first and sounds different: quieter, faster and more crackling. The usual account is that first crack is driven by steam and second crack by the bean's woody structure fracturing under heat and gas pressure. That is the trade's explanation; the measured part is the sound.
As the structure breaks down, the oils held inside the bean migrate to the surface, which is why dark roasts are glossy. The bean becomes more porous and more fragile. It has also lost considerably more weight than a light roast, as water and then some of the bean's own substance are driven off.
Why dark roasts taste alike
CoffeeHQ explanation
By this stage most of the acids and delicate aromatics that distinguish one coffee from another have been broken down, and the flavours left are largely those produced by roasting. Coffees from very different places converge. That is useful to a roaster who wants a blend to taste the same all year, and it is why dark roasting is sometimes used to disguise unremarkable coffee.
It is not a sign of low quality in itself. Southern Italian espresso, French-style coffee and many traditional blends are dark by design, and done well they are rich and sweet, not burnt.
Brewing without bitterness
Typical range
Dark roasts are brittle and porous, and the roast flavours in them turn bitter quickly. Common practice is the reverse of that for a light roast: cooler water, a coarser grind, less time. These rows are that practice, not findings.
| Variable | Typical range | What moving it does |
|---|---|---|
| Water temperature | About 85–92 °C | |
| Grind | A little coarser than you would use for a medium roast | |
| Contact time | Towards the shorter end for the method | |
| Espresso | Shorter ratios, around 1:1.5 to 1:2, extract well | |
| Rest after roasting | Short; often ready within days | Dark roasts are widely said to go stale sooner. The usual reasons given are the oil on the surface and the more open structure of the bean; neither was measured in a source read for this page. |
Directions from common practice, not settings. Adjust by taste.
Problems particular to dark roasts
CoffeeHQ explanation
- Harsh, ashy or burnt
Usually because: More taken from the coffee than tastes good, commonly put down to water that is too hot for a dark roast, or simply a strong brew. A dark roast is also bitter in itself.
Change first: Lower the water temperature first.
- Tastes rancid or like old oil
Usually because: Surface oils have oxidised. Dark roasts are widely said to stale faster than light ones.
Change first: Buy smaller amounts and use them sooner.
- Grinder gumming up, or beans sticking in a bean-to-cup machine
Usually because: Oil from the beans coats burrs, chutes and hoppers.
Change first: Clean the grinder more often.
Strong is not the same as caffeinated
CoffeeHQ explanation
Dark roast tastes stronger because it is more bitter and heavier in body. That is not a sign of more caffeine. Dark-roasted beans are lighter and larger, so a scoop of them contains less coffee than a scoop of light roast, and the one study read for this page, which brewed many roast degrees identically, found less caffeine in the cup from its darkest roasts than from its light and medium ones.
Nor is a dark roast gentler on the stomach in any dependable way. Claims of that kind turn on individual tolerance and are not something CoffeeHQ can advise on.
What to do next
- Light versus dark roast — The full comparison, with the caffeine arithmetic set out.
- What happens when coffee roasts — The stages up to and beyond second crack, in detail.
- Moka pot guide — A method traditionally paired with dark roasts, and how to avoid bitterness in it.
- The latte — The kind of milk drink dark roasts are often chosen for.
- Become a coffee expert — A structured programme from the plant and its processing to roasting, water and tasting.
- Colour
- Dark brown to near-black, visibly oily surface.
Possible flavour influence
- commonly produces more bitterness and roast-derived flavour, less origin character
Well established — Caffeine in the cup does not reliably increase with roast level despite common belief. One study that brewed many roast degrees identically found the least caffeine from its darkest roasts.