Introduction
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.
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.
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.
Conclusion
This experiment demonstrates that coffee origin significantly influences roasting outcomes. The altitude, processing method, and bean density all play a role in how flavors develop during roasting. Understanding these regional characteristics allows roasters to optimize their techniques to bring out the best in each coffee.
Future Experiments
To build on these findings, future studies could explore:
- The effect of different processing methods (washed vs. natural) within the same region.
- How variations in roast development time impact final flavor complexity.
- Pairing different roast levels with various brewing techniques to determine optimal extraction methods.
By continuously experimenting with roasting techniques, coffee professionals and enthusiasts can refine their understanding of how to bring out the most desirable attributes in different coffee origins.
