What Does the Washed Coffee Bean Process Actually Do?

The washed process removes floating beans, depulps the fruit, strips mucilage, ferments, rinses, dries, and hulls the seed. It is known for cleanliness, brightness, and clear acidity, and it serves as the flavor benchmark for many specialty regions. Global coffee bean production reaches about 8.4 billion kilograms a year, and processing steers how each lot tastes.

Within one region, washed coffee shows the bean's basic flavor, while natural and honey methods layer aroma and sweetness on top of that base. Put simply, washed coffee tastes of the bean itself, and natural coffee tastes of bean plus fruit pulp. Two washed examples, Kenya Asaliya and Yirgacheffe Gudingding, show how origin, variety, and altitude reshape one processing method.

The annual production of coffee beans reaches as high as 8.4 billion kilograms, and the processing method is one of the key steps that determines the direction of flavor. The washed process is known for its cleanliness, brightness, and prominent acidity, and is the foundational flavor benchmark for many specialty coffee regions. From the perspective of Front Street Coffee, this article systematically organizes the complete steps of the washed process—from removing floating beans, depulping and removing mucilage, fermentation, washing, to drying and hulling—and analyzes its advantages, disadvantages, and the causes of its flavor. At the same time, it compares the differences between natural and honey processes, and uses two washed beans, Kenya Asaliya and Yirgacheffe Gudingding, as examples to show the diverse expressions of the same processing method under different origins, varieties, and altitudes.

For more specialty coffee knowledge, please follow the WeChat official account: FrontStreet Coffee

Demand for coffee consumption continues to rise, and global annual coffee bean production has reached 8.4 billion kilograms, a considerable scale. Front Street believes that, beyond variety, origin, and cultivation methods, there is another key procedure that profoundly affects the final flavor: the processing method of coffee beans. Different processing methods lead the beans in completely different taste directions.

FrontStreet Coffee believes that coffee beans processed by the washed method have a neat appearance, outstanding visual appeal, and often the highest quality performance, with better acidity and brightness, clean flavor, and fewer off-flavors. Front Street also points out that in the same producing region, the washed method presents the coffee bean's basic flavor, while natural and honey processes layer aroma and some sweetness on top of this foundation. So the difference between the two coffee bean processing methods is: the washed method highlights the main flavor, while the natural method weakens the main flavor and adds aroma and sweetness, making a cup of coffee more complex. In other words, washed coffee is the taste of the bean itself, while natural coffee is the taste of the bean plus the fruit pulp. In FrontStreet Coffee's stores, we have specially set up display areas to showcase beans with different coffee bean processing methods and different roast levels for everyone's reference.

Are coffee beans coffee fruit?

When mature, the coffee fruit is yellow or red and looks like a miniature cherry, so it is also called a coffee cherry. What we usually call coffee beans are actually the seeds inside the coffee fruit, not the fruit itself (what we drink is the seed). The coffee fruit is composed of the skin, pulp, pectin, silver skin, and seed. So-called coffee processing is the process of separating the coffee bean from the fruit. Different processing methods also lead to different flavors after brewing. At present, the most common processing methods are divided into three categories: natural, washed, and honey. Below, FrontStreet Coffee will focus on the characteristics and process of the washed method.

▲ The skin part is basically removed during processing

Coffee Bean What is wrapped inside the silver skin is the endosperm, commonly known as the seed, which is our protagonist—the coffee bean.

Silver Skin Inside the parchment layer, the coffee bean is wrapped, and tightly attached to the bean surface is a very thin membrane much like rice paper. That is the epidermis left by seed development, called silver skin or chaff in the coffee world. Most of the silver skin falls off during processing (especially when the washed method is used). If it does not fall off, it is sometimes removed before shipment through a "polishing" step. Even without adding this procedure, the remaining silver skin will mostly fall off cleanly during roasting, leaving only a very small amount of fragments caught in the narrow slit of the bean's center line, which appear as pale yellow fine flakes mixed among the grounds during grinding.

Endocarp (Parchment) Below the mucilage, the layer tightly adhered to by the mucilage is a shell composed of cellulose. Each coffee bean has a layer of this shell, and this shell is the endocarp. After drying, the endocarp looks very much like Western parchment, hence the name parchment.

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

Pulp Directly below the epicarp is a thin layer of pulp. Except for the dry process, the outer skin is usually removed within just a few hours after the fruit is picked, and the pulp adhering to the inner side is removed along with it. Therefore, the earliest depulping machine designed was called a depulper.

Epicarp The outermost layer is the epicarp, abbreviated as skin. It is similar to the skin of a cherry or cranberry but somewhat tougher. In most coffee varieties, the skin is red when the fruit is ripe, though some are yellow or orange.

▲ Washed green beans

▲ Washed roasted beans

Washed Process:

The washed process uses fermentation to remove the pectin layer. After removing the skin of the coffee cherry, the pectin is removed through fermentation, and water is used to rinse away the pectin softened by fermentation. Then mechanical drying is used, and the drying process takes 1 to 2 days. Of course, sun-drying can also be used, but it takes relatively longer, requiring 3 to 16 days. Washed coffee beans are much more convenient than natural coffee beans. Defective beans can be largely removed directly during the washing process, and washed coffee beans have excellent visual appeal, so they are deeply favored.

Washed coffee is formed through the following steps:

1. Removing floating beans Pour the coffee beans into a large water tank. Underdeveloped, inferior beans will float to the surface, while ripe, full fruits will sink to the bottom. At this point, scoop out the floating beans on the surface, and the step of removing floating beans is complete.

2. Removing skin and pulp Use a pulping machine to remove the epicarp and pulp of the coffee fruit. (The mucilage, parchment, and silver skin will remain.)

3. Fermentation The purpose of this step is to use biological processing methods to remove the mucilage. The coffee fruit that has passed through the pulping machine.

4. Washing After completing fermentation and removing the mucilage, because fermentation bacteria and impurities remain on the coffee beans, the beans are washed again. In order to wash them clean, this step consumes a large amount of clean water.

5. Drying and removing parchment and silver skin Usually a machine is used (or sun-drying) to dry the coffee fruit, reducing the moisture content to 10~14%. Then a huller is used to remove the remaining parchment and silver skin, completing the processing.

Advantages and disadvantages of washed coffee beans

Advantages: 1. All procedures of the washed method are indoors, so impurities in the coffee beans can be minimized and quality is the highest. 2. Because the pulp is removed from the beginning, there is no need to worry about mold like with the natural method. 3. The appearance is relatively complete and the visual appeal is excellent.

Disadvantages: 1. The procedures are complex and cumbersome, so the cost is much higher than the natural method. 2. A large amount of clean water is used. Producing 1 kilogram of coffee beans requires consuming 40~50 liters of clean water, so it is less used in areas lacking water resources.

Flavor: Because of fermentation, the coffee beans usually carry bright acidity and fruity aroma.

During fermentation, biological processing methods are used to remove the mucilage. After fermentation is completed, a continuous supply of fresh water needs to be introduced in order to wash away the fermentation bacteria and impurities remaining on the coffee beans, so a large amount of clean water is used. Therefore, it is less used in areas lacking water resources. Although the washed method does not require worrying about mold, the fermentation process of the washed method has a certain impact on coffee flavor, so generally specialty coffee enthusiasts do not adopt this processing method. Washed coffee has a clean taste without off-flavors, and the coffee beans usually carry bright acidity and fruity aroma.

FrontStreet Coffee compares two washed beans, Kenya Asaliya and Ethiopian Yirgacheffe Gudingding, to see how coffee beans processed by the same washed method can differ.

FrontStreet Coffee: Kenya Asaliya Coffee Beans Region: Thika, Kenya Processing station: Asali Honey Processing Station Altitude: 1,550–1,750 meters Grade: AA TOP Variety: SL28, SL34 Processing method: Kenyan 72-hour washed

Roasting Curve This bean is full and round. In order to fully express its bright and mellow acidity, FrontStreet Coffee uses a light roast. Machine: Yangjia 800N, 550 g green beans charged Charge temperature: 200°C First crack: 5'30", 154.3°C Development after first crack 2'10'', discharged at 191.6°C

Kenyan 72-hour Process Abbreviated as K72. The coffee fruit is harvested when its ripeness reaches a sweetness of 21, the best fruits are selected for depulping, soaked in a fermentation tank for 24 hours using clean river water in the tank, washed after 24 hours, then soaked in clean river water for another 24 hours of fermentation, washed again, then fermented again, repeated 3 times, for a total fermentation time of 72 hours. Ordinary washed fermentation usually lasts at most 36 hours. This repeated processing method of fermenting and then washing gives Kenyan coffee beans a strong acidity and a delicate mouthfeel.

FrontStreet Coffee: Yirgacheffe Gudingding Cooperative Coffee Beans Region: Gedeo Zone, Yirgacheffe Altitude: 1900-2300m Variety: Heirloom Processing method: Washed Grade: G1

Roasting Curve Roaster Yangjia 800N (roast amount 300 grams) Charge temperature: 180°C, turning point: 5'00", 149.9°C, first crack: 8'42", 183.8°C, development after first crack 1'48", discharged at 193.5°C.

Brewing Suggestions FrontStreet Coffee conducted experiments using the same brewing method and data.

Filter: Hario V60, water temperature: 90°C, coffee-to-water ratio: 1:15; grind size: medium-fine (BG-6S: 80% passing through China standard No. 20 sieve) Brewing method: staged extraction. Use 30 grams of water for a 30-second bloom, pour in a small stream in circles until 125 grams, then pause. When the water level is about to expose the coffee bed, continue pouring until 225 grams and stop. When the water level is about to expose the coffee bed again, remove the dripper. (Timing starts at the beginning of the bloom.) Extraction time is 2'00".

Kenya Asaliya coffee brewing flavor: SL28 and SL34 from Kenya's Thika region, because the beans here have high acidity, clean and clear lines, and the most solid and rich mouthfeel, a full juicy sensation of smoked plum and cherry tomato, with the sweet-tartness of plum in the middle, and a finish with the fresh fragrance of snow pear.

Yirgacheffe Gudingding coffee brewing flavor: On the palate there are citrus and black tea; as the temperature changes, there are creamy, caramel, and almond finish notes, with obvious sweetness returning and a clean, sweet taste.

From the experiment, it can be seen that even for beans processed by the same washed method, the final flavor experience still differs because of other factors such as origin, altitude, and variety.

As for describing coffee taste, FrontStreet Coffee believes everyone will have their own interpretation, and what FrontStreet Coffee really wants to do is guide friends who are new to specialty coffee to find a connection between coffee and their taste buds, and to develop our sensory perception. This process is like a kind of training, a kind of conscious development. And after our sensitivity improves, we should let go of this pursuit of clear-cut flavors and instead adopt a more open attitude to feel the richness and changes of coffee, and to feel the beauty of a cup of coffee more purely.

The above content is compiled by CoffeeHunters, a coffee news website.