How does coffee bean processing change what ends up in the cup?

Global coffee bean production reaches about 8.4 billion kilograms a year, and processing decides much of the final flavor after variety, origin, and cultivation. Washed coffee is depulped soon after picking, fermented, and dried, giving neat beans, prominent acidity, clean flavor, and no off-tastes. Natural coffee dries the whole fruit, so fruit sugars stay in contact with the seed.

Washed lots express the bean's own flavor; natural and honey methods add aroma and sweetness on top, making the cup more layered. In the same region, washed coffee sets the basic flavor foundation, while natural coffee reads as bean flavor plus fruit pulp. Kenya Asaliya and Yirgacheffe Gotingding show how one coffee bean process performs across different origins and varieties.

The annual global production of coffee beans reaches as high as 8.4 billion kilograms, and what influences the final flavor of a cup of coffee, besides variety, origin, and cultivation methods, is another crucial step—the processing method. Front Street Coffee believes that different processing methods lead to completely different flavor directions. This article will provide an in-depth analysis of the complete process and characteristics of the washed processing method, starting from the anatomical structure of the coffee fruit, gradually breaking down each step of the washed method, and comparing the core differences with the natural method. At the same time, Front Street Coffee uses two washed beans—Kenya Asaliya and Yirgacheffe Gotingding—as examples, demonstrating through actual brewing experiments the flavor changes brought by different origins and varieties under the same processing method, helping coffee enthusiasts build a clearer framework for taste perception.

Today, coffee consumption demand continues to rise, and global annual coffee bean production has reached an astonishing scale of 8.4 billion kilograms. Front Street Coffee believes that the key factors determining coffee flavor, in addition to variety, origin, and cultivation methods, include a step that cannot be ignored—the coffee bean processing method. Different processing methods give coffee beans completely different flavor directions.

Front Street Coffee's view is that coffee beans obtained through the washed processing method have a neat appearance and excellent visual appeal, with the highest quality ceiling, and their acidity and brightness are more prominent, with a clean flavor and no off-tastes. Front Street believes that in the same producing region, the washed method presents the basic flavor foundation of the coffee bean, while the natural and honey methods add aroma and some sweetness on top of this foundation. Therefore, 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 layers. Simply put, washed is the taste of the bean itself, while natural is the taste of the bean plus the fruit pulp. In Front Street 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 to reference and compare.

Are coffee beans coffee fruit?

When mature, the coffee fruit turns yellow or red, and its shape closely resembles a miniature cherry, so it is also called a coffee cherry. What we commonly call coffee beans are actually the seeds inside the coffee fruit, not the fruit itself. From outside to inside, the coffee fruit consists of the skin, pulp, pectin, silver skin, and seed. So-called coffee processing is the process of separating the coffee beans from the fruit. With different processing methods, the flavor presented after brewing the coffee beans also changes accordingly. At present, the most common processing methods are divided into three types: natural, washed, and honey. Below, Front Street Coffee will focus on the characteristics and specific process of the washed processing method.

▲ The skin part is basically removed during processing

Coffee bean

What is wrapped by the silver skin is the endosperm, also commonly known as the seed, which is the protagonist we truly care about—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 similar to rice paper. That is the epidermis left during seed development, which the coffee industry calls silver skin or chaff. Most of the silver skin falls off during processing (especially when the washed method is used), and what does not fall off is sometimes removed by a "polishing" process before shipment. Even without this procedure, the small amount of remaining silver skin will basically fall off completely 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 into the grounds during grinding.

Endocarp (parchment)

The layer tightly adhered below the mucilage is a shell made of cellulose. Every coffee bean has such a layer of shell, which is the endocarp. After drying, the endocarp looks very much like Western parchment, so it is also called parchment.

Pectin layer

Below the pulp is the pectin layer, that is, the 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 exocarp is a thin layer of pulp. Except for the dry processing method, the outer skin is usually removed within just a few hours after the fruit is picked, and the pulp attached to the inner side is also removed together, so the earliest designed peeling machine was called a depulper.

Exocarp

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

▲ Washed green beans

▲ Washed roasted beans

Washed Process:

The washed processing method uses fermentation to remove the pectin layer. First, the skin of the coffee cherry is removed, then the pectin is decomposed through fermentation, and then the pectin softened by fermentation is rinsed off with clean water, after which mechanical drying is used. The drying process takes 1 to 2 days. Of course, sun drying can also be chosen, but it takes longer, requiring 3 to 16 days. Washed coffee beans are much more convenient than natural coffee beans. Defective beans can be removed in large quantities during the washing process, and washed coffee beans have excellent visual appeal, so they are very popular.

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 on the surface, while ripe, plump fruits sink to the bottom. At this point, scoop out the floating beans on the surface, completing the step of removing floating beans.

2. Removing skin and pulp Use a pulping machine to remove the exocarp and pulp of the coffee fruit. (At this point, the pectin, endocarp, and silver skin remain.)

3. Fermentation The purpose of this step is to remove the pectin through biological processing. Ferment the coffee fruit that has been processed by the pulping machine.

4. Washing After completing fermentation and removing the pectin, because fermentation bacteria and impurities remain on the coffee beans, the coffee beans need to be cleaned again. In order to clean them thoroughly, this step consumes a large amount of clean water.

5. Drying and removing the endocarp and silver skin Usually, machines are 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 endocarp and silver skin, completing the processing.

Advantages and disadvantages of washed coffee beans

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

Disadvantages: 1. The procedure is complex and cumbersome, so the cost is much higher than that of the natural method. 2. A large amount of clean water is used. For every 1 kilogram of coffee beans obtained, 40–50 liters of clean water are consumed, so it is less used in areas lacking water resources.

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

During fermentation, biological processing is used to remove the pectin. 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 consumed, which is why it is less commonly used in areas lacking water resources. Although the washed processing method does not require worrying about mold, the washed fermentation process has a certain impact on coffee flavor, so generally specialty coffee enthusiasts do not adopt this processing method. Washed coffee has a clean taste with no off-flavors, and the coffee beans usually carry bright acidity and fruity aromas.

Front Street Coffee compares two washed beans, Kenya Asaliya and Ethiopian Yirgacheffe Gotingding, to see how coffee beans under the same washed processing method differ.

Front Street 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 These beans are plump and round. In order to fully bring out their bright and full-bodied acidity, Front Street Coffee uses a light roast. Machine: Yangjia 800N, 550g 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 processing method Abbreviated as K72. Coffee fruits are harvested when their sweetness reaches a ripeness level of 21. The best fruits are selected for depulping, then soaked in a fermentation tank for 24 hours. Clean river water is used in the tank. After 24 hours, they are washed, then soaked in clean river water for another 24 hours of fermentation, washed again, and fermented again. This is repeated 3 times, for a total fermentation time of 72 hours. Ordinary washed fermentation lasts at most 36 hours. This repeated method of fermenting and then washing gives Kenyan coffee beans strong acidity and a delicate texture.

Front Street Coffee: Yirgacheffe Gotingding Cooperative Coffee Beans Region: Gedeo Zone, Yirgacheffe Altitude: 1,900–2,300 m Variety: Heirloom Processing method: Washed Grade: G1

Roasting curve Roasting machine Yangjia 800N (roasting capacity 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 suggestion Front Street Coffee conducts the experiment 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, then 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 filter. (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, with the full juicy sensation of smoked plum and cherry tomatoes, the mid-palate has the sweet-tartness of plum, and the finish has the fresh fragrance of snow pear.

Yirgacheffe Gotingding coffee brewing flavor: On entry there are citrus and black tea, and as the temperature changes there are creamy, caramel, and almond notes in the finish, with obvious sweetness returning and a clean, sweet mouthfeel.

From the experiment, it can be seen that even for beans under the same washed processing method, due to other factors such as origin, altitude, and variety, the final flavor experience still differs.

When it comes to describing coffee flavor, Front Street Coffee believes everyone will have their own interpretation. What Front Street Coffee truly 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 sense of taste. This process is like training, a kind of conscious development. And when our sensitivity improves, we can then set aside this pursuit of definite flavors and adopt a more open attitude to feel the richness and changes of coffee, and more purely feel the beauty of a cup of coffee.

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