Why Roast Level Matters
Roast degree isn’t just a colour change - it rewrites the bean’s chemistry, shifting everything from sweetness and acidity to grind size and brew time. Understanding these changes lets you dial-in flavour rather than leave it to chance.
- Maillard Magic & Caramelisation - As heat drives the Maillard reaction, sugars and amino acids create the caramel, nut, and chocolate notes we love. Lighter roasts stop early (more fruit), while darker roasts push deeper (more caramel and smoke).
- Acidity vs Body Balance - Light roasts keep natural acids intact for a bright, crisp cup. Medium roasts mellow acidity and boost sweetness. Dark roasts sacrifice brightness for fuller body and a rich, syrupy mouthfeel.
- Solubility & Extraction Window - Roasting alters bean solubility. Light beans resist water, calling for finer grinds and longer brew times; dark beans extract quickly, thriving with coarser grinds and faster pours.
- Caffeine Perception (Not Quantity) - Roast level has only a minor effect on caffeine content, but the lighter body of light roasts can make them feel stronger, whereas dark roasts taste bold yet may register as smoother.
- Brew-Method Compatibility - Pour-over and AeroPress accentuate the delicacy of light roasts; drip machines and moka pots love the balance of medium; espresso and French press showcase the crema and heft of dark.
Master these variables and you’ll choose a roast, and dial in a brew, with intention, unlocking flavours that match your palate every time.
The roast spectrum
Light
Flavour profile:
Bright citrus, stone-fruit, and floral aromatics; tea-like clarity.
Acidity & body:
High-pitched acidity, light body, clean finish.
Roast point:
Pulled just after first crack (≈ 196 – 205 °C); beans stay dry, no surface oils.
Agtron Gourmet colour range:
65 – 80
Best brewing methods:
V60, Chemex, AeroPress, filter cold brews
Medium
Flavour profile:
Balanced caramel sweetness, milk chocolate, gentle fruit undertones.
Acidity & body:
Moderate acidity, round mouthfeel, balanced.
Roast point:
Between first and second crack (≈ 206 – 219 °C); light brown beans, minimal oil.
Agtron Gourmet colour range:
50 – 64
Best brewing methods:
Drip machine, moka pot, espresso for milk drinks.
Dark
Flavour profile:
Bold cocoa, toasted nuts, smoky depth, lingering bittersweet finish.
Acidity & body:
Low acidity, full-bodied, syrupy mouthfeel.
Roast point:
Through second crack (≈ 220 – 230 °C); dark brown-to-black beans with oily sheen.
Agtron Gourmet colour range:
25 – 49
Best brewing methods:
Espresso, French press, stovetop percolator, cold-brew concentrate.
What happens during roasting
Roasting is a six-step heat journey that lasts 10–20 minutes and peaks around 230 °C. Here’s the timeline, with the key sights, smells, and temperatures you’ll notice.
1. Drying OutGreen beans quickly shed moisture (about half of their water content) while still looking pale. The gentle hiss of steam sets the stage for even browning later on.
Time: 0 – 3 min
Bean temp: ~130 °C
Flavour / aromas: Grassy steam, very mild sweetness beginning to form.
2. YellowingColour shifts to straw-yellow as sugars start to form; the smell moves from grassy to warm cereal, hinting at sweetness to come.
Time: 3 – 6 min
Bean temp: 150 – 165 °C
Flavour / aromas: Warm bread, cereal, hints of honey.
3. First CrackInternal steam makes the beans pop like popcorn, doubling their size. Stopping here preserves bright, fruit-forward flavours prized in light roasts.
Time: 6 – 9 min
Bean temp: ~196 °C
Flavour / aromas: Bright citrus, florals, fresh fruit acidity.
4. Caramel Sweet-SpotCaramelisation deepens, turning sharp acids into chocolate-caramel sweetness and giving medium roasts their balanced body.
Time: 9 – 12 min
Bean temp: 200 – 218 °C
Flavour / aromas: Milk chocolate, soft caramel, balanced sweetness.
5. Second CrackA softer crack signals cell walls fracturing again. Surface oils appear, acidity drops, and flavours shift to bittersweet cocoa and gentle smoke.
Time: 12 – 14 min
Bean temp: 219 – 230 °C
Flavour / aromas: Dark cocoa, toasted nuts, gentle smokiness.
6. Cooling & RestingBeans are cooled within minutes to lock in flavour, then allowed to rest for a day or two while they release CO₂ and stabilise for brewing.
Time: Immediate cool to < 40 °C, then 1 – 2 days rest
Bean temp: Quick drop from roast peak
Flavour / aromas: Final profile stabilises - cups taste best 1–5 weeks post-roast.
How Roast Level Shapes Flavour
Roasting turns raw, grassy-green beans into the aromatic, flavour-packed coffee you brew every day.Time and temperature determine which compounds develop or degrade, so a coffee’s roast level - light, medium or dark - directly steers its acidity, sweetness, body and overall flavour profile.
Light 195-205 °C
Key Chemical Changes
Sugars are only starting to caramelise; organic acids stay intact. Surface remains dry.
Flavour impact
Bright acidity, crisp fruit and floral notes, clear origin character.
Best for
Pour-over, AeroPress, other filter methods.
Tends to showcase citrus, berry, & stonefruit profiles
Medium 205-215 °C
Key Chemical Changes
Maillard browning peaks, sugars caramelise, balanced acids and oils.
Flavour impact
Rounded sweetness, balanced acidity-to-bitterness, emerging caramel, nut and milk-chocolate tones
Best for
Espresso, Coffee with Milk, Aeropress.
Tends to showcase nutty, caramel & deeper fruit profiles
Dark 215 °C+
Key Chemical Changes
Sugars fully caramelise then pyrolyse, surface oils appear, acids largely break down.
Flavour impact
Low acidity, heavy body, pronounced cocoa, smoke, and earthy depth. Origin nuance subdued.
Best for
French press, moka-pot, milk-forward espresso.
Tends to showcase earthy, chocolate & spice profiles
Quick Sensory Queues
Colour
Light cinnamon → rich chestnut → near-black sheen
Aroma When Grinding
Fresh citrus & sweet grain in light roasts, malt & toffee in medium, dark chocolate & smoke in dark.
Crema
Lighter roasts create pale, quickly fading crema. Darker roasts produce thick, dark crema.
Now that you're an expert, how about you
Explore coffees by roast.
Multiple Origins
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Roast
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Multiple Origins
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Single Origin
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Roast
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Single Origin
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Frequently Asked Roast Questions
Which roast has the most caffeine?
Caffeine changes very little during roasting. Measured by weight, a light roast retains slightly more because the beans are denser, but the difference per cup is minimal - brew method and dose matter far more than colour.
Why do dark-roast beans look oily?
Extended heat drives natural oils to the surface once the beans pass second crack. The sheen is normal, not a sign of added flavouring or staleness. Just keep oily beans in airtight containers to slow oxidation.
Does roast level affect acidity?
Yes. Light roasts keep more of coffee’s natural acids, giving a bright, fruity snap. Medium roasts mellow that acidity, while dark roasts taste smoother and lower-acid because many of those compounds break down with longer heat.
Can I use light roasts for espresso?
Absolutely, many specialty cafés do. Expect to grind a touch finer, use slightly higher brew pressure or longer pre-infusion, and aim for a longer extraction to balance the higher density and acidity.
How long do roasted beans stay fresh?
Flavour peaks about 7–42 days after roast, then gradually softens. Well-sealed beans remain enjoyable for 43–56 days, but aromatics fade once the bag is opened. Buy little and often for the brightest cups.
Does roast level change my grind size?
Yes. Light-roast beans are denser and require a finer grind to extract fully. Dark roasts are more brittle, so start slightly coarser, adjust until your brew tastes balanced.
Still not sure what you're after?
Read our other Coffee Guides
Receive guidance on finding your ideal coffee in two other quick reads. From origin stories to flavour-profiles, these guides give you the know-how to shop with confidence.
