If coffee cherries are not processed promptly after picking, they will quickly ferment and spoil, affecting the final flavor. Natural (dry) and washed (wet) processing are the two most fundamental methods, each shaping a completely different coffee character. Natural beans retain a full, natural mellow body, with soft aroma and rich mucilage; washed beans have bright, lively acidity, elevated aroma, and a clean mouthfeel. For enthusiasts who pursue a thick, full-bodied espresso, the proportion of natural beans can be appropriately increased; while washed beans, because they have fewer off-flavors and excellent acidity, are often an important source of sweetness in espresso. This article will break down in detail the seven core stages of the washed method—selecting beans, removing pulp, fermentation, washing, drying, hulling, and sorting and grading—to help readers fully understand the profound impact of this fine processing flow on coffee flavor.

After coffee cherries are picked, they must enter the processing stage as soon as possible; otherwise, fermentation will quietly begin, causing the beans to take on unpleasant odors. Common processing methods fall into two major categories, natural and washed, and the flavor directions they ultimately present are completely different. Naturally processed beans retain a full natural mellow taste, with a gentle aroma and a relatively high mucilage content; washed beans have good body, elevated aroma, and bright acidity.

Mellowness is an indispensable element of espresso, bringing a rich and smooth mouthfeel experience similar to liquor. Those who prefer espresso can appropriately increase the proportion of natural beans. Washed beans, by contrast, are as clean and transparent as a clear wind chime, with very few off-flavors. In addition, washed beans perform excellently in acidity and are the main contributor of sweetness in espresso.

The specific operational process of the washed method is as follows:

1. Selecting beans:

Pour freshly harvested coffee cherries into a water-filled tank and soak them for about 24 hours. During this period, fully developed cherries will sink to the bottom, while unripe and overripe cherries will float on the surface, allowing them to be removed.

2. Removing pulp:

Use a machine to strip off the skin and pulp, leaving only the coffee beans wrapped in the parchment layer. At this point, a layer of mucilage still clings to the surface of the beans, and the core goal of the washing stage is to clean this mucilage off completely.

3. Fermentation:

The mucilage adheres quite strongly to the beans and is difficult to remove by water alone, so the beans need to be placed in a tank for about 18 to 36 hours, using fermentation to break down the mucilage. Fermentation methods are divided into two types: wet fermentation and dry fermentation; the former adds water, while the latter does not. During fermentation, complex chemical changes occur between the seed and the remaining fruit mucilage, and this is the step in the washed method that has the greatest impact on coffee flavor. Some farms shorten fermentation time by adding hot water or enzymes, but doing so has an adverse effect on quality, and specialty coffee enthusiasts do not approve of it.

4. Washing:

Farms using the washed method must build washing channels and be able to continuously introduce flowing fresh water. During operation, place the fermented beans into the channel and push them back and forth, using the friction between the beans and the scouring force of the water flow to wash the coffee beans until their surface is smooth and clean.

5. Drying:

After washing is completed, the coffee beans are still wrapped in the parchment layer, with a moisture content of about 50%, and must be dried to reduce the moisture content to 12%; otherwise, the beans will continue to ferment and then become moldy and spoiled. The more ideal drying method is natural sun drying. Although it takes one to three weeks, the flavor performance is outstanding and is deeply favored by enthusiasts. Some producing regions use machine drying, greatly compressing the processing cycle, but the flavor of the finished product is not as good as that of sun-dried coffee.

6. Hulling:

Once drying is complete, the beans can be stored directly in a warehouse or sent to a factory for hulling to remove the parchment layer and silver skin.

7. Sorting and grading:

As with natural processing, washed coffee also needs to go through sorting and grading, the purpose being to remove defective beans and ensure that quality reaches a relatively high standard, after which it is handed over to exporters to be sold around the world.

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