The Foundation of Coffee Roasting

Coffee beans are the cornerstone of the coffee roasting process. Understanding their origin, types, and characteristics is essential for any aspiring coffee roaster. In this section, we will delve into the fascinating world of coffee beans, exploring their journey from the plant to your cup, and how different factors influence their flavor and quality.

The Coffee Plant

Coffee beans are the seeds of the Coffea plant, which is part of the Rubiaceae family. There are over 100 species of Coffea, but the two most commonly cultivated and commercially important ones are Coffea arabica (Arabica) and Coffea canephora (Robusta).

1. Arabica Coffee (Coffea arabica):

   • Origin: Native to Ethiopia and the Arabian Peninsula.
   • Flavor Profile: Known for its smooth, complex flavors with a wide range of taste notes, including fruity, floral, and nutty.
   • Growing Conditions: Prefers high altitudes (600-2,200 meters above sea level), cooler climates, and well-drained, fertile soil.
   • Caffeine Content: Lower than Robusta, typically around 1.5%.
   • Shape and Size: Oval-shaped with a curved crease.

2. Robusta Coffee (Coffea canephora):

   • Origin: Native to central and western sub-Saharan Africa.
   • Flavor Profile: More robust and bitter, with earthy and woody notes.
   • Growing Conditions: Thrives at lower altitudes (sea level to 800 meters), warmer climates, and can withstand harsher conditions.
   • Caffeine Content: Higher than Arabica, typically around 2.7%.
   • Shape and Size: Rounder and smaller with a straight crease.

The Journey of a Coffee Bean

The journey of a coffee bean from plant to cup involves several stages, each contributing to the final flavor and quality of the coffee.

1. Cultivation:

   • Coffee plants are typically grown in tropical regions within the “Coffee Belt,” which spans between the Tropics of Cancer and Capricorn. The ideal conditions include consistent temperatures between 15-24°C (59-75°F), ample rainfall, and rich soil.

2. Harvesting:

   • Coffee cherries are hand-picked or mechanically harvested when they reach peak ripeness. Harvesting methods include selective picking (only ripe cherries) and strip picking (all cherries from a branch).

3. Processing:

   • Once harvested, coffee cherries undergo processing to remove the outer pulp and extract the beans. Common processing methods include:
     • Washed (Wet) Process: Beans are fermented to remove the mucilage, then washed and dried. This method produces a clean, bright flavor.
     • Natural (Dry) Process: Cherries are dried whole, and the dried pulp is removed. This method results in a fruity, fuller-bodied flavor.
     • Honey Process: A hybrid method where some mucilage is left on the beans during drying, resulting in a balanced flavor profile.

4. Drying:

   • Processed beans are dried to reduce moisture content to about 10-12%. Drying methods include sun drying on patios or raised beds and mechanical drying.

5. Milling:

   • Dried beans undergo hulling to remove the parchment layer, polishing to remove any remaining silver skin, and grading/sorting based on size, weight, and defects.

6. Exporting:

   • The beans, now referred to as green coffee, are packed in jute or burlap sacks and exported to coffee roasters around the world.

Factors Influencing Coffee Bean Quality

Several factors influence the quality and flavor profile of coffee beans. Understanding these factors can help you select the best beans for your roasting endeavors.

1. Origin and Terroir:

   • The geographical location, climate, soil composition, and altitude where the coffee is grown significantly impact its flavor profile. For example, Ethiopian coffee is known for its bright, fruity notes, while Colombian coffee is celebrated for its balanced, rich flavor.

2. Varietal:

   • Different coffee plant varieties within Arabica and Robusta species have unique characteristics. Varietals like Bourbon, Typica, Geisha, and SL28 each contribute distinct flavors and attributes to the beans.

3. Processing Method:

   • The method used to process coffee cherries affects the bean’s final flavor. Washed beans tend to have cleaner, brighter flavors, while natural processed beans are often fruitier and fuller-bodied.

4. Harvesting Practices:

   • Selective picking ensures that only ripe cherries are harvested, resulting in higher quality beans. Poor harvesting practices, such as picking unripe or overripe cherries, can negatively affect the flavor.

5. Storage:

   • Proper storage of green coffee beans is crucial to maintaining their quality. Beans should be stored in cool, dry conditions, away from direct sunlight and strong odors. Properly stored beans can remain fresh for up to a year.

Tasting and Evaluating Coffee Beans

Cupping is the standard method used by coffee professionals to taste and evaluate coffee beans. It involves brewing coffee under controlled conditions to assess its aroma, flavor, acidity, body, and aftertaste. Here’s a basic guide to cupping:

1. Preparation:

   • Grind the coffee beans to a coarse consistency.
   • Place a specific amount of ground coffee into each cup.
   • Pour hot water (just off the boil) over the grounds, filling the cup.

2. Crust and Aroma:

   • Allow the coffee to steep for about 4 minutes.
   • Break the crust (layer of grounds on top) with a spoon, releasing the coffee’s aroma.
   • Smell the coffee immediately after breaking the crust to assess its aroma.

3. Tasting:

   • After breaking the crust, skim off any remaining grounds.
   • Slurp the coffee from a spoon, allowing it to spread across your palate.
   • Evaluate the flavor, acidity, body, and aftertaste.

4. Recording Notes:

   • Take detailed notes on each aspect of the coffee. This helps you understand the unique characteristics of different beans and refine your roasting process.

Conclusion

Understanding coffee beans is fundamental to mastering the art of coffee roasting. By appreciating the journey of the bean from plant to cup and recognizing the factors that influence its quality, you’ll be better equipped to select and roast beans that suit your taste preferences. Remember, every coffee bean has a story to tell, and as a roaster, you have the opportunity to bring that story to life in each cup.

As you continue your journey in coffee roasting, keep experimenting with different beans, origins, and processing methods. Embrace the diversity of flavors and enjoy the endless possibilities that coffee roasting offers.

Happy roasting!