Natural (Dry) Process

The natural process is the original coffee processing method, used for centuries in Ethiopia and Yemen where coffee originated. It remained the dominant method globally until the washed process was developed in the 19th century. Brazil adopted the natural process as its standard in the 19th century due to its suitability for large-scale, water-scarce production. In the 2000s, the natural process saw a resurgence in specialty coffee as producers developed techniques to produce clean, high-quality natural coffees rather than the defect-prone naturals of the past.

In the natural process, the entire coffee cherry (skin, pulp, mucilage, and seed) is dried together. As the cherry dries, the fruit ferments around the seed. The sugars in the pulp and mucilage undergo microbial fermentation (yeasts and bacteria), producing alcohols, acids, and esters that infuse into the seed. The drying fruit acts as a sealed environment for fermentation, and the compounds produced diffuse into the bean. This is why natural coffees have pronounced fruity, winey, and fermented flavors. The seed also absorbs pigments and sugars from the drying fruit, contributing to the heavier body and sweetness. The challenge is that the fermentation is less controlled than in the washed process, making consistency difficult.

1. Harvesting: Ripe cherries are selectively picked (ripeness is critical for naturals). 2. Sorting: Cherries are sorted to remove defects, under-ripes, and over-ripes. 3. Pre-drying: Cherries may be pre-dried briefly on raised beds or patios. 4. Drying: Cherries are spread in thin layers on raised beds or patios and dried in the sun for 15-30 days. 5. Raking: Cherries are raked regularly (every few hours) for even drying and to prevent mold. 6. Covering: Cherries are covered during rain, at night, and during the hottest midday hours. 7. Moisture monitoring: Drying continues until cherries reach 10-12% moisture. 8. Hulling: The dried cherry (now called dried cherry or pod) is hulled to remove the dried fruit and parchment. 9. Sorting and Grading: The green coffee is sorted by size, density, color, and defects.

Fermentation in the natural process occurs during drying, not in a separate tank. As the cherry dries, naturally occurring yeasts and bacteria ferment the sugars in the pulp and mucilage. This fermentation is uncontrolled and varies with temperature, humidity, and the microbiome of the cherry. The fermentation produces alcohols, acids, and esters that infuse into the seed. This is what gives natural coffees their characteristic fruity, winey, and fermented flavors. The fermentation continues until the moisture content drops low enough (below 15%) to halt microbial activity. The risk is that over-fermentation produces undesirable fermented, rotten, or moldy flavors.

Drying is the most critical and time-consuming step in the natural process, taking 15-30 days. Cherries are spread in thin layers (2-5 cm) on raised beds or patios. They must be raked regularly (every 2-4 hours) to ensure even drying and prevent mold growth. The cherries are covered during rain and at night to prevent re-wetting. Drying too fast can result in uneven drying and cup defects; drying too slowly risks mold and over-fermentation. The target moisture is 10-12%. Raised African beds are preferred for better airflow. Some producers use mechanical dryers to finish the drying process.

Dried natural cherries (pods) can be stored before hulling for several months in breathable bags in dry, ventilated conditions. After hulling, green coffee is stored in GrainPro or hermetic bags. Natural coffees are often more sensitive to storage conditions than washed coffees due to their higher sugar content. Store at 15-25 C with 50-60% relative humidity. Natural coffees may lose quality faster than washed coffees during long-term storage.

• •Requires no water (ideal for water-scarce regions)
• •Produces intense, fruity, and sweet flavors prized in specialty coffee
• •Lower infrastructure investment than washed process
• •Heavy body and complex flavor profile
• •Traditional method with cultural significance in Ethiopia and Brazil
• •Can produce exceptional, unique cup profiles when managed well

• •Inconsistent flavor profile (harder to control fermentation)
• •Higher risk of defects (mold, over-fermentation, uneven drying)
• •Longer drying time (15-30 days vs. 7-15 for washed)
• •Labor-intensive (frequent raking required)
• •Vulnerable to rain and humidity during drying
• •May mask the coffee's inherent terroir with processing flavors
• •Risk of 'fermented' defect if drying is too slow

Natural process coffees are characterized by heavy body, low-to-medium acidity, and pronounced fruity flavors (strawberry, blueberry, tropical fruit). They often have winey, fermented, and sweet notes. The fruit-derived flavors come from the fermentation and sugar absorption during drying. Natural coffees from Ethiopia (particularly the Harrar and Sidama regions) are famous for their blueberry and strawberry notes. Brazilian naturals tend to have chocolate, nutty, and dried fruit flavors. The natural process masks some of the coffee's inherent terroir, making it harder to distinguish varietal and origin characteristics. However, well-executed naturals can produce incredibly complex and intense cups.

• •Over-fermentation (rotten, vinegary, fermented flavors) from slow or uneven drying
• •Mold (earthy, musty flavors) from inadequate raking or covering
• •Rio defect (medicinal, iodine-like taste) from specific microorganisms during drying
• •Uneven drying causing inconsistent cup quality
• •Phenolic defect (chemical, medicinal taste)
• •Insect damage during the long drying period
• •'Potato' defect (particularly in African naturals) from insect damage

The natural process has the lowest water usage of all processing methods, requiring essentially no water. This makes it environmentally favorable in water-scarce regions. However, the large land area required for drying can be a concern. The process produces no wastewater, eliminating water pollution issues. The main environmental concern is the long drying time, which requires favorable weather. Climate change and unpredictable rainfall are making natural processing more challenging in traditional regions.

• •Raised African beds for better airflow and more even drying
• •Controlled-environment drying (greenhouses, solar dryers) to protect from rain
• •Pre-sorting by density (flotation) to ensure uniform ripeness before drying
• •Extended fermentation on raised beds (Aerobic Natural process) for unique flavors
• •Anaerobic natural fermentation (drying cherries in sealed bags before sun drying)
• •Mechanical dryers with temperature and humidity control for finishing

• •Chapter 2: Processing Methods
• •Chapter 1: The History of Coffee

• •Specialty Coffee Association
• •Coffee Processing: A Guide
• •Brazilian Specialty Coffee Association