Testing Different Coffee Beans: How Origin Affects Roasting Profiles
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The origin of coffee beans plays a significant role in how they respond to roasting. Factors such as altitude, climate, soil composition, and processing methods contribute to the density and chemical composition of beans, which in turn influence how they react to heat. This experiment explores how beans from different regions—Ethiopia, Colombia, Brazil, and Sumatra—develop distinct roast profiles and flavor characteristics.
Who is this for?
Eight O’Clock Original is perfect for traditional coffee drinkers who crave a smooth, full-bodied brew. With 100% Arabica beans, this medium roast delivers a classic flavor profile loved for generations. It’s a reliable choice for drip machines, French press, or grinders—ideal for everyday enjoyment without sacrificing quality.Each region’s beans bring unique qualities that require specific roasting techniques to maximize their flavor potential. By understanding these differences, roasters can optimize their approach to highlight the best attributes of each origin. This study aims to provide insights into how varying environmental and processing conditions influence roasting outcomes and final taste profiles.
List of Our Favourite Coffee Beans Origins
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Coffee Bean Selection and Characteristics
Ethiopia (Yirgacheffe)
Ethiopian coffee beans, particularly from Yirgacheffe, are known for their high acidity, floral aroma, and citrusy flavors. These beans typically grow at high altitudes (1,800-2,200 meters), leading to slower maturation and higher density. The washed processing method commonly used in Ethiopia enhances clarity and brightness in the cup, making these beans ideal for light to medium roasting.
Colombia (Huila)
Colombian coffee, especially from Huila, is renowned for its balanced acidity, caramel sweetness, and medium body. Grown at altitudes ranging from 1,200 to 1,800 meters, these beans provide versatility in roasting. The washed process ensures consistency and clean flavors, which makes Colombian coffee a favorite among specialty roasters.
Brazil (Minas Gerais)
Brazilian beans, commonly grown at lower altitudes (800-1,200 meters), are naturally processed and known for their nutty, chocolatey, and smooth characteristics. These beans have lower acidity and tend to develop caramelized flavors in medium to dark roasts. Their mild flavor profile makes them a staple in espresso blends and commercial coffee production.
Sumatra (Mandheling)
Sumatran coffee, especially Mandheling, is known for its full body, low acidity, and earthy, herbal notes. These beans are typically grown at altitudes of 1,000-1,500 meters and undergo a unique wet-hulled processing method, which imparts a bold, complex character. Sumatra beans excel in medium-dark to dark roasts, where their deep, savory flavors can fully develop.
Roasting Methodology
Experimental Setup
Each sample was roasted under carefully controlled conditions:
- Roaster Type: Drum roaster
- Batch Size: 200g per sample
- Roasting Time: 10–14 minutes
- Target Roast Levels: Light, Medium, and Dark
- Monitoring: The first crack and second crack were recorded for each batch to determine optimal development times.
By maintaining consistent roasting parameters, we could isolate the effects of bean origin on final flavor characteristics without introducing confounding variables.
Temperature and Development Time
Temperature control was key to achieving the best roast for each origin.
- Light roasts were stopped shortly after the first crack at around 385°F (196°C) to retain acidity and delicate notes.
- Medium roasts were extended slightly to 410°F (210°C) to balance sweetness and complexity.
- Dark roasts reached 440°F (227°C) and beyond, where caramelization intensified and bitterness increased.
Diagram: Roasting Profiles of Different Coffee Origins
(Below is a diagram illustrating how roasting profiles change for beans from Ethiopia, Colombia, Brazil, and Sumatra, showing the impact on acidity, sweetness, and body at different roast levels.)
Results & Observations
| Origin | Roast Level | Acidity | Sweetness | Body | Flavor Notes |
|---|---|---|---|---|---|
| Ethiopia | Light | High | Bright | Light | Floral, Citrus, Tea-like |
| Ethiopia | Medium | Moderate | Balanced | Medium | Berry, Honey, Caramel |
| Ethiopia | Dark | Low | Reduced | Heavy | Spiced Cocoa, Toasted Nuts |
| Colombia | Light | Moderate | Crisp | Light | Apple, Caramel, Cocoa |
| Colombia | Medium | Balanced | Rich | Medium | Nutty, Brown Sugar, Chocolate |
| Colombia | Dark | Low | Mild | Heavy | Dark Chocolate, Smoky |
| Brazil | Light | Mild | Nutty | Medium | Peanut, Chocolate, Dried Fruit |
| Brazil | Medium | Balanced | Smooth | Medium-Heavy | Milk Chocolate, Hazelnut, Caramel |
| Brazil | Dark | Low | Mild | Heavy | Bitter Chocolate, Toasty, Molasses |
| Sumatra | Light | Mild | Earthy | Heavy | Herbal, Woody, Savory |
| Sumatra | Medium | Low | Subtle | Full-bodied | Tobacco, Spice, Dark Chocolate |
| Sumatra | Dark | Very Low | Minimal | Very Heavy | Smoky, Leather, Bold |
Key Takeaways
- Ethiopian beans performed best at light to medium roasts, preserving their floral and citrusy brightness. The washed process enhanced their clarity, making them ideal for pour-over methods.
- Colombian beans were the most adaptable, delivering balanced acidity and sweetness across all roast levels. Their versatility makes them suitable for various brewing methods, from espresso to drip coffee.
- Brazilian beans exhibited their best flavors in medium to dark roasts, with caramel, nutty, and chocolatey notes becoming more pronounced. Their natural processing method contributed to their smooth, full-bodied nature.
- Sumatran beans developed rich, earthy flavors at medium-dark and dark roasts, with a heavy body and deep, complex notes. The wet-hulled process made them distinct from other origins, favoring darker roast styles.
How Variations in Roast Development Time Impact Final Flavor Complexity
I’ve stood at the roaster watching first crack roll in like summer rain—soft pops, then a lively patter—and felt that familiar mix of excitement and respect. From that moment forward, every second of development time (the period after the first crack until the drop) is a choice about flavor. Nudge it short, and you can preserve crystalline acidity and aromatic lift. Stretch it longer, and you convert precursors into caramels and chocolates, build density in the mid-palate, and deepen structure. Get it just right for the coffee at hand, and the cup blooms with layered complexity.
This piece unpacks what development time does, how it interacts with rate of rise and end temperature, why a “longer = better” mindset can backfire, and how to taste for the difference at home—whether you roast or simply brew with keen curiosity.
Quick Primer: Where “Development Time” Fits in the Roast
A roast typically moves through three overlapping arcs:
- Drying (green to yellow): Moisture is driven off, and grassy notes begin to fade.
- Maillard (yellow to first crack): Browning reactions build sweetness, color, nutty/toffee notes, and the scaffolding for body.
- Development (first crack to drop): Sugars and acids are reorganized; aromatics, sweetness, and body consolidate; roast markers (cocoa, caramel, toasted, sometimes smoky if pushed) grow.
Development time (DT) is not isolated—it’s the last movement of a symphony. What came before sets the stage: a hot, fast Maillard arc vs a gentle, extended one will make the very same development window taste completely different. That’s why two roasts can have identical DT percentages and taste nothing alike.
Development Time vs Development Percentage
Roasters often reference Development Time Ratio (DTR): DT divided by total roast time (e.g., 1:30 DT in a 9:00 roast ≈ , 16.7%). It’s a handy comparative tool, but it is not flavor law. A light, high-grown Ethiopian can sing at 12–14% on one machine and needs 18–20% on another, depending on batch size, thermocouple sensitivity, and rate of rise (RoR) behavior. Use DTR as a contextual metric, not a target painted on the wall.
The Levers That Make DT Matter (Far) More Than a Number
1) Rate of Rise (RoR): The “Shape” of Development
RoR is the speed at which bean temperature is increasing. If DT is the scene, RoR is the lighting—you can make the same scene look tender, harsh, or flat depending on how you light it.
- Smooth, gently declining RoR during development: tends to deliver sweetness with clarity and layered acidity.
- Crash (sharp RoR drop at first crack): risks baked, bready, or hollow cups even if DT is “correct.”
- Flick (RoR spikes late): can imprint sharp, roast-dominant edges—think singed or astringent finishes—again, regardless of clock time.
Takeaway: Complexity loves a stable, graceful RoR curve more than it loves an exact DT timestamp.
2) End Temperature (Drop Temp)
The drop temperature decides how far you push Maillard and caramelization by the end.
- Lower drop with a modest DT: delicate florals and citrus, higher perceived acidity, but potential for underdeveloped texture if you starve it.
- Higher drop with a modest DT: rounder sweetness and cocoa at the cost of some top notes; can be great for espresso density.
- Higher drop with a long DT: risks monotony (flat chocolate, smoked sugars) if the coffee’s innate acidity is fragile.
Takeaway: DT without a meaningful drop in temp context is like judging a movie by its runtime.
3) Green Coffee Density, Moisture, and Variety
High-density, high-grown coffees tolerate longer DTs and higher drop temps if RoR is controlled; they can convert that heat into complexity. Softer beans (lower elevation, older crop) can lose aromatics quickly and head toward papery or woody if you linger.
Takeaway: Let the coffee’s structure decide how much development it can absorb before flavor narrows.
4) Batch Size and Probe Reality
Tiny batches warm fast; probe readings lag differently across machines. A 90-second DT on one roaster is not the same physics on another. Taste + data beats data alone.
What Actually Changes in the Cup as DT Varies?
With Shorter Development Time (relative to that bean and profile)
- Aromatics: Brighter florals and esters; stone fruit and citrus can sparkle.
- Acidity: More pronounced and higher-toned; malic/citric feel is defined.
- Sweetness: Lighter, cane sugar/honey rather than caramel.
- Body: Leaner; tea-like or silky rather than creamy.
- Risks: “Grassy,” cereal, or “peaky” acidity if too short for the bean/roast curve; channeling in espresso due to brittle solubility.
With Longer Development Time
- Aromatics: More caramelized, cocoa, toasted nuts; florals recede.
- Acidity: Softer, rounder; lactic impressions can emerge; risk of flattening if overdone.
- Sweetness: Deeper; caramel, panela, toffee.
- Body: Fuller, heavier mid-palate; chocolate resonance.
- Risks: Baked flatness (doughy, bready), astringent finish if there’s a late flick, loss of origin character.
Complexity emerges when sweetness, acidity, and aromatics coexist—which often means avoiding both extremes: not so short that sugars stay shy, not so long that acids dull and aromatics collapse.
Complexity Is a Relationship, Not a Point
Think of flavor complexity as interlocking gears:
- Top notes (fruit, floral)
- Core (sweetness, recognizable origin character)
- Base (body, cocoa/toast, structure)
If DT is too short, the base gear doesn’t engage; you get aroma fireworks without a foundation. If DT is too long, the top gear disengages; you get body and chocolate without lift. Complexity is the hum when all three gears mesh. It’s why a roast with a slightly shorter DT but better RoR control can taste far more complex than one with a classic “safe” DT number but a crash-and-flick curve.
Matching Development to Brew Method
Filter (Pour-Over, Batch)
Filter rewards clarity and balance. Many washed, high-acid coffees shine with moderate DT and a clean declining RoR. Short DTs pop but can feel thin; longer DTs can taste comfy but less articulate.
Target feel: sweet-forward with organized acidity and intact aromatics.
Immersion (French Press, Cupping)
Immersion accentuates body and tamps down jagged acidity. You can go slightly shorter DT on brighter coffees and still taste complete cups. Very long DTs can turn murky here.
Target feel: creamy body with distinct, not muddy, sweetness.
Espresso
Espresso stresses solubility and structure. A bit more DT (or a touch higher drop temp) can deliver a syrupy mouthfeel and stabilized acidity. Too short = under-extracted citric spikes; too long = astringent, roast-forward.
Target feel: dense sweetness, supported acidity, clean finish.
Tasting Your Way to the Right DT (Even If You Don’t Roast)
You can tell a lot about development just by tasting:
- Underdeveloped cues: cereal/doughy aroma, “green peanut,” papery finish, acidity that buzzes without sweetness supporting it.
- Baked cues: muted aromatics, cardboard/stale pastry, sweetness that’s broad but bland, finish that fades too fast.
- Nicely developed: vivid but not shrill acidity; sweetness that’s present early and carries; aroma that matches flavor (not just in the dry fragrance); finish that leaves a clear memory of fruit or floral over a sweet base.
Brew the same coffee 3 ways—slightly different grind settings or temperatures—and note which presentation makes the most of what’s there. Well-developed coffees are forgiving; underdeveloped or baked coffees become more obvious as you change parameters.
For Home Roasters: Practical Development Experiments
- Two-Profile Split:
Roast A and Roast B to the same end temperature, but make Roast A with a smoother RoR and 15% DTR, Roast B with a sharper RoR and 18% DTR. Cups side by side after 3, 7, and 14 days.- You’ll likely prefer the smoother RoR even with the shorter DT; sweetness presents earlier, and acidity sits comfortably.
- End Temp Hold, DT Ladder:
Keep pre-crack identical. At first crack, create three versions: 60s, 90s, 120s DT, all with gently declining RoR.- Most dense washed Ethiopians sing at 75–105s; some naturals like 90–120s; many Brazils flatten if you push beyond 100–110s without very careful RoR.
- Crash/Flick Awareness:
Make two “wrong” roasts to train your palate: one with a deliberate crash at first crack (starve the gas), and one with a late flick (add gas late). Keep DT identical to a “good” control roast.- You’ll taste how a curved shape can ruin a perfectly respectable DT.
- Machine Reality Check:
Log bean probe and environmental probe. If your first crack is consistently “late” vs expected, your probe may read cool; adjust expectations. Taste > numbers.
How Origin, Process, and Altitude Nudge Ideal DT
- Washed Ethiopia/Kenya (high altitude): Often love shorter-to-moderate DT with scrupulous RoR. You’re protecting florals/berry acids while rounding the core.
- Natural Ethiopia/Colombia: Can handle moderate DT; you’re threading big fruit and keeping the jammy notes from turning stewed.
- Brazil/Lower Elevation Lots: Benefit from firm Maillard but careful DT; push too long and complexity narrows to generic cocoa/nut.
- Honey/Lactic-leaning Fermentations: Already soft and sweet; over-long DT can muddy. Emphasize curve quality over minutes.
Degassing, Rest, and Perceived Development
Development interacts with resting time. Highly aromatic light roasts might need 3–7 days to steady; dense anaerobics can open up around day 7–10; chocolate-leaning longer DT roasts often show well sooner for espresso. If a coffee tastes thin on day 2, don’t rush to blame DT—revisit on day 6 with a slightly finer grind.
Troubleshooting Flavor Complexity
- Thin, sharp, perfumey but not sweet: Likely too short DT or a crash. Try immersion brews; if roasting, add 10–20s of DT with a smoother RoR.
- Big body but dull fruit; mid-palate blob: Possibly too long DT or a late flick. Back the DT off by 10–20s, or lower, drop 1–2°C with a cleaner decline.
- Chocolatey yet astringent tail: Often a flick or pushing development without enough Maillard scaffolding. Strengthen early RoR gently; don’t slam late heat.
Why “Longer DT = Sweeter” Isn’t Always True
It’s tempting to add time until sweetness shows up, but sweetness has two parents: Maillard development and clean development shape. If Maillard was rushed, extra DT can “brown” sugars into amorphous roast notes without actually sweetening the structure. You want the conveyor belt from pre-crack into development to flow—then minimal DT can taste sweeter than a meandering, overlong finish.
From Roaster to Brewer: Making the Most of What You Have
If your bag tastes like it had a short DT (zippy, light body):
- Use a higher brew temperature (94–96°C) and a finer grind to coax sweetness.
- Consider immersion or thicker filter papers that increase contact time.
- For espresso, longer ratios (1:2.2 to 1:2.5) and slightly hotter shots often stabilize acidity.
If your bag tastes like it had a long DT (dense, chocolate-forward, muted top notes):
- Drop brew temp slightly (90–93°C) to dodge astringency, grind a hair coarser, and agitate less.
- For espresso, shorter ratios (1:1.8 to 1:2.0) can focus sweetness without dragging tannins.
Best Selections on Amazon to Explore Development Time Differences
If you want to taste how development choices change a cup—or start roasting at home—these approachable, commonly available picks make the learning curve friendlier:
Fresh Roast SR540 Coffee Roaster
A compact fluid-bed roaster with responsive controls. Great for learning how subtle gas adjustments change RoR and how the last 60–90 seconds reshape sweetness and aromatics.
Fresh Roast SR800 Coffee Roaster
More capacity and airflow headroom than the SR540, helpful for experimenting with curve shape and DT without crashing or flicking as easily.
Behmor 2000AB Plus Drum Coffee Roaster
A drum roaster that offers gentler heat transfer and larger batch sizes. Perfect for practicing steady, declining RoR and disciplined DT endings for chocolate-forward precision.
Gene Cafe CBR-101 Coffee Roaster
A popular home drum roaster with good visibility and control, ideal for hands-on tests of identical end temps with different DTs and curve shapes.
Volcanica Coffee — Ethiopia Yirgacheffe (Roasted Whole Bean)
If you’re not roasting, this bright, floral origin is an excellent “development detector.” Brew across methods to feel how a roast’s DT preserves or mutes top-end florals while delivering sweetness.
A Personal Benchmark: The 90-Second Sweet Spot
On my setup, dense washed Ethiopians often peak with about 75–95 seconds of post-crack development at a restrained drop temp, provided the RoR rolls down smoothly. Below 70 seconds, I get showy aromas but a hollow mid-palate. Beyond 100, citrus becomes marmalade and the florals wiltBrazilisls, by contrast, reward a touch more time—but demand excellent curve discipline; if I flick late, I trade nut-butter creaminess for a drying finish. Your gear and probes will differ, but the pattern—balance over bravado—hour.
A Sensory Exercise You Can Do Today (No Roaster Needed)
- Buy a washed Ethiopian and a Brazilian natural from the same roaster.
- Brew both as a pour-over at 92°C, ratio 1:16.
- Re-brew both at 96°C and slightly finer.
- Note how the Ethiopian’s top notes either bloom into sweetness (a well-developed roast) or turn glassy and sharp (likely under-developed). Watch how the Brazil either grows creamy and caramelized (thoughtful development) or slumps into flat cocoa (overlong or flicked).
You’ll begin to “hear” development time with your palate.
The Mental Model That Keeps Me Honest
I picture development as closing the circle:
- Drying prepares ingredients.
- Maillard cooks them into a sauce.
- Development reduces and seasons the sauce until flavors knit.
Stop too early, and the sauce tastes watery and raw. Reduce forever, and it’s sticky, dark, and one-note. Complexity is that moment when the sauce both coats the spoon and still tastes of the original ingredients.
Final Thoughts
Development time is neither a trophy nor a trap. It’s a relationship with the coffee’s density, the earlier phases of the roast, your roaster’s thermodynamics, and the curve you draw through first crack. A few extra seconds can save a cup or sink it; a clean declining RoR can make 80 seconds taste sweeter than 110; the “right” DTR shifts with origin, process, altitude, and machine.
If you roast, log curves, taste relentlessly, and change one variable at a time. If you brew, tunegrind, and temperature to amplify what development gave you. Either way, the reward is the same: a cup where fruit, sweetness, and body speak together—where you taste place, process, and craft in balance. That’s flavor complexity born not from guesswork, but from seconds that were chosen with care.
