The plant that started it all
Coffee is the fruit of a shrub from the genus Coffea. There are more than 120 species, but only two dominate the global market: Coffea arabica (Arabica) and Coffea canephora (Robusta). If you’re going to dedicate yourself to specialty coffee, your world will revolve almost exclusively around Arabica — although specialty Robusta exists and is growing.
Arabica grows between 800 and 2,200 meters above sea level, in what’s known as the “coffee belt” (between the Tropics of Cancer and Capricorn). It’s more susceptible to pests and diseases, requires more care, produces lower yield per plant, but in exchange offers complex flavor profiles: acidity, sweetness, fruity and floral notes.
Robusta grows at lower altitude, resists pests better, produces more fruit, and has nearly double the caffeine. Its profile tends to be more bitter, earthy, and body-heavy. It’s the base of most instant coffee and commercial Italian espresso blends. Don’t dismiss it — a well-cultivated and processed Robusta can be interesting, especially in espresso blends.
Varieties: the DNA of flavor
Within Arabica there are dozens of varieties, each with genetic characteristics that influence flavor. The most relevant:
Typica and Bourbon are the “parent” varieties from which almost all others descend. Bourbon tends to be sweet with bright acidity. Typica is clean and delicate.
Caturra and Catuai are mutations/crosses of Bourbon and Typica, more compact and productive. Very common in Latin America. Solid profiles, good acidity and sweetness.
SL28 and SL34 were developed in Kenya in the 1930s. They’re famous for intense acidity, blackcurrant and tomato notes — the classic “Kenya” profile that’s unmistakable.
Geisha (or Gesha) is the star variety of specialty coffee. Originally from Ethiopia, it became famous when Finca La Esmeralda in Panama presented it in competition. Intense floral notes (jasmine, bergamot), tea-like acidity, extraordinary complexity. Also extraordinarily expensive.
Castillo and Colombia are varieties resistant to coffee rust, developed by Cenicafé in Colombia. Historically dismissed by purists, but modern versions have improved significantly in the cup.
Variety matters, but it’s not everything. A poorly processed Geisha can taste worse than a well-cared-for Caturra. Processing is where many coffees are made or ruined.
The cherry: what you really harvest
What we call a “coffee bean” is actually the seed inside a fruit — the coffee cherry. The structure from outside to inside:
- Skin (exocarp) — the outer layer, red or yellow when ripe
- Pulp (mesocarp) — the sweet, mucilaginous layer
- Mucilage — sticky layer rich in sugars surrounding the bean
- Parchment (endocarp) — protective papery layer
- Silver skin — thin layer attached to the bean
- Bean (endosperm) — what we roast and grind
Each cherry normally contains two flat beans (face to face). Sometimes only one develops, forming a peaberry — round and generally with a more concentrated flavor.
Processing: where the profile is defined
After harvesting the cherries, you need to separate the bean from the fruit and dry it. How this is done has enormous impact on the final flavor. The three main methods:
Washed (wet process)
The “cleanest” method. The cherry is mechanically depulped, fermented in water tanks to dissolve the mucilage (typically 12-72 hours), washed with clean water, and dried in the sun or mechanical dryers.
Cup profile: Bright and defined acidity, clean flavor, clear origin characteristics. When someone says a coffee “tastes like its origin,” it’s probably washed. Classic examples are washed Ethiopias with jasmine and lemon notes, or washed Colombias with caramel and green apple.
Natural (dry process)
The oldest method. The entire cherry is dried in the sun with all the pulp and mucilage intact. The bean absorbs sugars from the fruit over weeks of drying.
Cup profile: Heavy body, intense sweetness, fermented fruity notes (strawberry, blueberry, wine). Natural Ethiopias from regions like Guji or Sidamo are famous for bursting with fruit. The risk: if drying isn’t uniform, unpleasant fermented flavors appear.
Honey (pulped natural)
A middle ground. The cherry is depulped but some or all of the mucilage is left on the bean during drying. Depending on how much mucilage is left, it’s classified as:
- White honey: very little mucilage (~10-20%)
- Yellow honey: some mucilage
- Red honey: most of the mucilage
- Black honey: all the mucilage, slow drying
Cup profile: Pronounced sweetness, medium-high body, moderate acidity. Combines the cleanliness of washed with the sweetness of natural. Costa Rica pioneered this method.
Anaerobic and experimental processing
The current frontier of coffee. Cherries or depulped beans are fermented in sealed tanks without oxygen, sometimes with controlled yeasts or bacteria. Results are intense and unconventional flavor profiles: bubble gum notes, cinnamon, tropical fruits. Coffees like those from Diego Bermúdez (Finca El Paraíso, Colombia) have put these methods on the map with very high scores.
Drying and storage
After processing, the coffee is dried to reach between 10-12% moisture — measured with a hygrometer. Too much moisture creates mold; too little overdries the bean and loses flavor.
Dry coffee is stored in parchment until ready to export. Before shipping, it goes through a huller that removes the parchment and is sorted by size and density. The result is green coffee — the product that roasters buy.
Well-stored green coffee (in jute sacks or GrainPro, in cool and dry conditions) can maintain its quality for 6-12 months. After that it starts to “age” — loses acidity and vibrancy.
What you need for this lesson
- Your tasting journal
- If you can, buy two coffees from the same origin but different processing (for example, a washed Ethiopia and a natural Ethiopia) to notice the difference processing makes
Practical exercise
The next time you buy specialty coffee, read the complete label and write down in your journal: origin (country, region, farm if possible), variety, altitude, processing, roast date. After brewing it, note how you describe it. Try to connect what you know about the processing with what you’re tasting. Is it a natural? Notice more fruit? Is it washed? Is it “cleaner”?
Over time, this exercise will let you predict flavor profiles before tasting — and that’s a professional barista skill.
Key concepts from this lesson
- Arabica is the specialty coffee species; grows at altitude, more complex in flavor
- Varieties (Bourbon, Geisha, SL28, etc.) define the genetic potential of flavor
- Processing (washed, natural, honey) transforms that potential into cup profile
- Washed = clean and acidic; Natural = fruity and sweet; Honey = balance between both
- Experimental processing (anaerobic) is redefining the limits of flavor
- Well-stored green coffee lasts 6-12 months; after that it loses quality