What is the Washed Processing Method? The Steps of Washed Coffee Beans and Why They Have a Clean Flavor

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The demand for coffee continues to grow, with global coffee bean production reaching an impressive 8.4 billion kilograms annually. According to FrontStreet Coffee, in addition to variety, origin, and cultivation methods, another crucial factor affecting coffee flavor is the coffee bean processing method. Different processing methods will reveal different flavors in coffee beans.

FrontStreet Coffee believes that washed processing creates uniform, aesthetically pleasing coffee beans with the highest quality, excellent acidity, and brightness, delivering clean flavors without impurities. FrontStreet Coffee considers that within the same growing region, washed processing represents the fundamental flavor profile of coffee beans, while natural and honey processing build upon this foundation by adding aroma and some sweetness. The difference between these two processing methods can be understood as: washed processing highlights the main flavor profile, while natural processing softens the main flavor and adds aroma and sweetness, making a cup of coffee more complex. Therefore, the distinction between these processing methods can be seen as: washed is the taste of the bean itself, while natural is the taste of the bean plus fruit pulp.

At FrontStreet Coffee, we have set up dedicated display areas to showcase coffee beans with different processing methods and roasting levels for your reference.

Are Coffee Beans Actually Coffee Fruits?

When coffee fruits ripen, they turn yellow or red and resemble smaller cherries, hence they are also called coffee cherries. What we commonly refer to as coffee beans are actually the seeds inside the coffee fruit, not the fruit itself (concept of drinking seeds). Coffee fruits consist of skin, pulp, mucilage, silver skin, and seeds. Coffee processing is the process of separating coffee beans from the fruit. Different processing methods will affect the flavor presented when coffee beans are brewed. Currently, the most common processing methods are natural, washed, and honey processing. In the following article, FrontStreet Coffee will focus on introducing the characteristics and process of washed coffee bean processing.

▲ The skin part is basically removed during the processing

Coffee Beans

Enclosed within the silver skin is the endosperm, commonly known as the seed - our main character, the coffee bean.

Silver Skin

Inside the parchment layer lies the coffee bean, which is tightly wrapped in a very thin membrane resembling rice paper. This is the epidermis left from seed development, known in the coffee industry as silver skin or chaff. Most of the silver skin falls off during processing (especially with washed processing). Unremoved silver skin is sometimes eliminated through "polishing" before shipping. Even without this step, the remaining silver skin mostly comes off cleanly during roasting, leaving only tiny fragments in the bean's central crease. When grinding coffee beans, these appear as light yellow fine particles mixed with the grounds.

Endocarp (Parchment)

Beneath the mucilage layer, tightly adhered to it, is a shell composed of cellulose. Each coffee bean has such a shell, which is the endocarp. When dried, the endocarp resembles Western parchment paper, hence the name parchment.

Pectin Layer

Beneath the pulp is the pectin layer, also known as mucilage. The mucilage is both sweet and sticky, and coffee farmers habitually call it "Miel" (Spanish for honey). In botany, the pulp and mucilage together are called the mesocarp.

Pulp

Directly beneath the exocarp is a thin layer of pulp. Except for dry processing, the skin is usually removed within hours after harvesting, and the adhering pulp is also removed. Therefore, the earliest designed depulping machine was called a depulper.

Exocarp

The outermost layer is the exocarp, simply called the skin, which is similar but tougher than cherry or cranberry skin. For most coffee varieties, the fruit skin turns red when ripe, though some are yellow or orange.

▲ Washed Raw Beans

▲ Washed Roasted Beans

Washed Processing Method:

Washed processing uses fermentation to remove the mucilage layer. After removing the coffee cherry skin, fermentation is used to remove the mucilage, then washed with water to rinse the softened mucilage from fermentation, followed by mechanical drying. The drying process takes 1 to 2 days. Natural drying can also be used, but it takes longer, requiring 3 to 16 days. Washed coffee bean processing is much more convenient than natural processing, as defective beans can be largely eliminated during the washing process, and washed coffee beans have excellent appearance, making them very popular.

Washed coffee processing involves the following steps:

1. Removing Floating Beans

Coffee beans are poured into large water tanks. Underdeveloped, low-quality beans will float to the surface, while mature, full fruits will sink to the bottom. At this point, the floating beans are removed, completing the floating bean removal step.

2. Removing Skin and Pulp

Through a pulping machine, the exocarp and pulp of the coffee fruit are removed. (This leaves mucilage, endocarp, and silver skin).

3. Fermentation

The purpose of this step is to use biological treatment methods to remove the mucilage. Coffee fruits processed by the pulping machine are fermented.

4. Washing

After completing fermentation and removing mucilage, fermentation bacteria and impurities remain on the coffee beans, so they are washed again. To clean thoroughly, this step consumes large amounts of fresh water.

5. Drying and Removing Endocarp and Silver Skin

Usually, machines (or sun drying) are used to dry the coffee fruits until moisture content reaches 10-14%. Then, a hulling machine is used to remove the remaining endocarp and silver skin, completing the processing.

Advantages and Disadvantages of Washed Coffee Bean Processing

Advantages:

1. All processing steps in washed processing are done indoors, so impurities in coffee beans can be minimized, achieving the highest quality.
2. Since the pulp is removed from the beginning, there's no need to worry about mold problems like in natural processing.
3. The appearance is more complete and aesthetically pleasing.

Disadvantages:

1. The process is complex and tedious, so costs are much higher than natural processing.
2. Large amounts of fresh water are used - producing 1 kilogram of coffee beans requires 40-50 liters of fresh water, so it's less commonly used in water-scarce regions.

Flavor Profile:

Due to fermentation, coffee beans typically have bright acidity and fruit aroma. Biological treatment methods are used during fermentation to remove mucilage. After fermentation completes, continuous fresh water is needed to thoroughly clean the fermentation bacteria and impurities remaining on the coffee beans. This requires large amounts of fresh water, so it's less commonly used in water-scarce regions. Although washed processing doesn't have mold concerns, the fermentation process does affect coffee flavor to some extent, so some specialty coffee enthusiasts don't prefer this processing method. Washed coffee has a clean taste without impurities, and coffee beans typically have bright acidity and fruit aroma.

FrontStreet Coffee compares two washed beans - Kenya Asalia and Ethiopia Yirgacheffe Gedeb - to see the differences between coffees with the same processing method.

FrontStreet Coffee: Kenya Asalia Coffee Beans

• Region: Thika, Kenya
• Processing Station: Asali Honey Processing Station
• Altitude: 1550-1750 meters
• Grade: AA TOP
• Variety: SL28, SL34
• Processing Method: Kenya 72-hour Washed

Roasting Profile

These beans are full and round. To fully express their bright, mellow acidity, FrontStreet Coffee uses light roasting.

• Machine: Yangjia 800N, 550g green beans input
• Entry Temperature: 200℃
• First Crack: 5'30", 154.3℃
• Development after First Crack: 2'10", discharged at 191.6℃

Kenya 72-Hour Processing Method

Simply abbreviated as K72. Select coffee cherries with sweetness level 21 at optimal ripeness for harvesting, screen the best fruits for depulping, soak in fermentation tanks for 24 hours using clean river water, wash after 24 hours, then soak again in clean river water for 24 hours, wash again, then ferment again, repeating 3 times for a total fermentation time of 72 hours. Regular washed fermentation takes at most 36 hours. This repeated fermentation and washing method gives Kenyan coffee beans strong acidity and delicate texture.

FrontStreet Coffee: Yirgacheffe Gedeb Cooperative Coffee Beans

• Region: Yirgacheffe, Gedeo Zone
• Altitude: 1900-2300m
• Variety: Heirloom
• Processing Method: Washed
• Grade: G1

Roasting Profile

• Roaster: Yangjia 800N (300g batch)
• Entry Temperature: 180℃
• Yellowing Point: 5'00", 149.9℃
• First Crack: 8'42", 183.8℃
• Development after First Crack: 1'48", discharged at 193.5℃

Brewing Recommendations

FrontStreet Coffee conducted experiments using the same brewing method and parameters.

• Dripper: Hario V60
• Water Temperature: 90℃
• Coffee-to-Water Ratio: 1:15
• Grind Size: Medium-fine (BG-6S: 80% pass-through through China standard #20 sieve)
• Brewing Method:分段式萃取 (Segmented extraction). Use 30g water for bloom for 30 seconds, pour in a small circular motion to 125g for segmentation, continue pouring to 225g when water level drops to expose the coffee bed, stop pouring, remove the dripper when water level drops to expose the coffee bed again (timing starts from bloom), extraction time 2'00".

Tasting Results:

Kenya Asalia Coffee Brewing Flavor:

SL28 and SL34 from Kenya's Thika region. Beans from this area have high acidity, clean flavor lines, and the most solid, rich mouthfeel. Full plum-cherry juice sensation, with plum sweetness in the mid-range, and a crisp pear aroma in the aftertaste.

Yirgacheffe Gedeb Coffee Brewing Flavor:

Initial taste shows citrus and black tea notes. As temperature changes, cream, caramel, and almond notes emerge with obvious sweet aftertaste and clean, refreshing mouthfeel.

From these experiments, we can see that even with beans processed using the same washed method, different factors such as origin, altitude, and variety result in different flavor experiences.

Regarding the description of coffee flavors, FrontStreet Coffee believes everyone will have their own interpretation. What FrontStreet Coffee truly wants to do is guide friends new to specialty coffee to find a connection between coffee and their taste buds, developing our sensory perception. This process is like a form of training, a conscious development. When our sensitivity improves, we can then let go of chasing specific flavors and instead use a more open attitude to experience the richness and variations of coffee, more purely experiencing the beauty of a cup of coffee.

Important Notice :

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FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473