How Coffee Beans Are Processed Before Roasting

Ever wonder why some coffees taste clean and bright while others are heavy and fruity? The secret starts long before roasting—with how the raw coffee bean is processed after harvest. Your cup’s clarity, sweetness, and body all trace back to whether the coffee was washed, dried, or something in between.

There are two main ways green coffee beans are prepared for roasting: the washed (wet) process and the natural (dry) process. Washed processing costs more and is used for high-quality beans, while natural processing is cheaper and typically used for lower-grade coffee. Over 80% of Arabica beans are washed, with exceptions in Brazil, Ethiopia, and parts of Indonesia.

What Is Coffee Processing?

Coffee processing prepares the harvested coffee cherry for roasting by removing the fruit and drying the bean inside. The method chosen—washed or natural—affects flavor, quality, and price. The two processes differ mainly in how and when the coffee fruit is removed from the bean.

How the Natural (Dry) Process Works

The natural (or dry) process is the original and simplest method. Whole coffee cherries are spread out to dry in the sun without removing the fruit or pulp. This method is cheap and is commonly used for lower-grade beans. It’s especially common in Brazil and Ethiopia, and sometimes used for robusta in Indonesia—but rarely.

How the Washed (Wet) Process Works

The washed (wet) process is more complex, labor-intensive, and expensive—but it produces cleaner, more consistent flavors and reduces defects. In this method, the coffee fruit’s outer skin and pulp are removed within 12–24 hours of harvest, before the beans are dried. This separation is critical for quality.

The fruit is crushed in a pulper with fixed and moving surfaces—or via movable rods—that separate the pulp from the bean. This must happen quickly after picking. Then the beans are rinsed, often using grading channels or an Aagaard separator (designed by a Norwegian grower in Kenya) that sorts beans by density as they settle in water. The process recycles water where possible.

Fermentation and Washing

After pulping, coffee beans are fermented in tanks for 12–36 hours. Fermentation uses enzymes to dissolve the sticky mucilage layer around the beans. Time depends on temperature, mucilage thickness, and microbial activity. Once done, the beans feel rough like pebbles rather than slippery.

Quality control is essential during wet processing. Even one spoiled bean can ruin a batch. Equipment must be cleaned daily to prevent contamination. Proper handling ensures the beans remain undamaged and defect-free.

Drying the Parchment Coffee

Post-fermentation, beans are still coated in a parchment-like husk (called parchment) and hold around 15% moisture. They must be dried down to about 11% for safe storage. Drying too much—below 10%—can dull the bean’s blue-green color and degrade quality.

Drying is done on cement, stone, or wooden surfaces—similar to the dry process. Large farms in rainy areas might use mechanical dryers with controlled airflow, but most rely on the sun. Beans are turned regularly during sun drying, which takes 12–15 days. Sun intensity must be managed; shade may be needed. The goal is to dry the parchment evenly without cracking.

Storing Parchment Coffee

Once dried, the beans are referred to as parchment coffee, named for their papery husk. They’re stored this way until just before export. Unlike fresh cherries, parchment coffee is stable—but still sensitive to humidity and heat. Arabica should ideally not sit more than 12 hours at origin, especially at high altitudes, due to moisture risks. Robusta can handle slightly longer storage.

Ideally, parchment coffee is kept in cool, stable environments away from the farm, often at similar elevations to where it was grown. High humidity (above 70%) and heat are the main threats.

Hulling (Removing the Parchment)

Before export, the parchment layer is removed in a process called hulling. Wet-process parchment is harder to remove than dry-process husks, so specialized machines are used. Two common types are friction hullers (like Engelberg or African models) and pressure hullers.

Friction hullers (such as the Smout machine, invented by Belgian Jules Smout in Guatemala) gently rub beans against rotating screws and serrated walls to remove parchment. The Smout machine operates slowly, generating less heat. Pressure hullers, more common outside Brazil, use centrifugal force and metal pins to detach the parchment. Beans must have the right moisture level—around 11%—to avoid breakage during hulling.

Polishing (Optional Step)

After hulling, a thin silver skin may remain on the bean. Some processors polish it off using machines with copper drums instead of iron to reduce damage. Polished beans are sometimes considered higher grade, though studies show no real flavor difference in the cup. The polished look is often subjective, and evidence of taste impact is inconclusive.

Frequently Asked Questions

What are the two main ways to process coffee beans?

The two main methods are washed (wet) and natural (dry) processing. Washed processing removes the coffee cherry’s skin and pulp before drying, while natural processing dries the whole cherry with the fruit still on the bean. Washed coffee generally yields cleaner, more consistent flavors, while natural coffee tends to be fruitier and heavier.

Why is the wet process more expensive than the dry process?

The wet process requires more equipment, water, and labor. It involves removing the coffee pulp within 12–24 hours of harvest, fermenting the beans to remove mucilage, and carefully drying them. Each step demands precision, infrastructure, and quality control to avoid spoilage—raising costs compared to simply sun-drying whole cherries.

How long does it take to dry coffee beans?

Drying time depends on the method. Sun drying parchment coffee takes about 12–15 days with regular turning. Natural processed cherries can take up to 30 days, especially in regions like Ethiopia. Mechanical drying is faster but less common and usually used in humid or rainy climates to prevent spoilage.

What is coffee parchment?

Coffee parchment is the thin, paper-like husk that surrounds the coffee bean after the fruit pulp is removed and the bean has been dried. It protects the bean and helps maintain stability during storage. The beans are stored as parchment coffee until just before export, when the parchment is removed.

Does polishing coffee beans improve flavor?

No, polishing coffee beans does not significantly improve flavor. It removes the outer silver skin but has little to no impact on taste in the cup. Historically, polished beans were considered higher quality, but blind tastings show negligible differences. Polishing is mostly an aesthetic step.

What happens if coffee beans are dried too much or too little?

If coffee beans are dried too much (below 10% moisture), they can lose color and quality. If dried too little (above 12%), they risk mold or spoilage during storage. The ideal moisture level is around 11% for safe, long-term storage and optimal roasting performance.

Recommended FrontStreet Beans for Natural and Washed Processing

Explore FrontStreet Coffee’s naturally processed Ethiopia Yirgacheffe Red Cherry, featuring intense tropical fruits and floral brightness from careful sun drying. For washed process clarity, try Ethiopia Huakui, showcasing clean jasmine, citrus, and balanced sweetness through traditional washing. Both beans highlight how processing shapes flavor. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.