1. Cherry Processing Chemistry
Before coffee beans are roasted, they exist as seeds inside coffee cherries. Post-harvest processing involves removing the cherry fruit layers (skin, pulp, mucilage) to isolate the seed.
The method used to remove these layers alters the chemical composition of the green seed, dictating sugar content, organic acids, and flavor precursors.
Key Takeaway: The Processing Choice
Post-harvest processing is a major factor shaping coffee flavor profiles. Natural processing yields rich fruitiness and heavy body. Washed processing delivers crisp acidity and a clean mouthfeel.
2. The Natural Dry Process
In natural (dry) processing, the entire coffee cherry is dried on raised beds under the sun before hulling.
As the cherry dries over several weeks, natural fermentation occurs within the fruit pulp. The sugars and organic compounds in the mucilage penetrate the seed, resulting in a cup with high sweetness, thick body, and intense fruit notes (like berries, tropical fruits, and wine).
3. The Washed Wet Process
In washed (wet) processing, the cherry skin and pulp are stripped mechanically, and the seeds are fermented in water tanks to dissolve the remaining sticky mucilage before drying.
This highlights the seed's organic origin flavors rather than fermentation compounds. Washed coffees feature bright acidity, light body, and distinct origin characteristics.
Beginner Pitfall: Over-extracting Natural Coffees
Natural processed coffee contains high levels of soluble simple sugars. This makes them highly soluble, meaning they extract very quickly. Keep temperatures slightly cooler (e.g., 91°C) to avoid pulling bitter notes.
4. Common Extraction Adjustments
- For Naturals: Use slightly lower water temperature and less agitation to prevent sweet notes from turning bitter.
- For Washed: Use hotter water (e.g., 94°C) to fully develop and highlight origin acidity.
5. Quick Comparison Table
Processing Comparison
- Natural: Sun-dried with fruit. Flavor: Berry, winey, sweet, high body.
- Washed: Pulp stripped, water fermented. Flavor: Clean, floral, citrus, high acidity.
- Honey: Partial pulp left on seed. Flavor: Balanced sweetness, medium body.
