Flavor Differences Among the Three Main Coffee Bean Processing Methods: Taste, Variety Characteristics, Origin Regions, and Grind Settings

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Among customers who now come to FrontStreet Coffee to buy beans, more and more people are noticing the processing methods of each coffee variety, which indicates that everyone's understanding of coffee is increasing. Therefore, FrontStreet Coffee would like to take this opportunity to introduce common coffee processing methods to everyone.

Natural Processing Method

FrontStreet Coffee will first introduce the natural processing method—the earliest method used for coffee fruit processing. This is a relatively ancient processing method for coffee beans, commonly used in Ethiopia, the homeland of coffee. First, the harvested coffee fruits are manually sorted to remove defective beans. Then the coffee fruits can be placed on raised beds or waterproof tarps. If equipment is relatively simple, some places directly spread them on concrete floors. However, this can cause coffee beans to pick up dust, earthy flavors, or mix in debris like sand or stones during collection.

FrontStreet Coffee has learned from research materials that the drying time for coffee fruits is approximately 27-30 days. At this point, the moisture content of coffee fruits will drop to about 11%-13%, reaching the standard. Then hulling machines can be used to remove the fruit peel and pulp. Another manual selection will be performed because during the hulling process, since the coffee beans are relatively dry and brittle, broken beans need to be sorted out.

The main advantage of this natural processing method is that it has low equipment requirements—natural processing can be carried out as long as the weather is clear. Therefore, African regions like Ethiopia, with their dry weather and low rainfall, are quite suitable for adopting this processing method. Many of the coffee beans available at FrontStreet Coffee use natural processing, such as the Ethiopian Yirgacheffe Natural Red Cherry, which develops fermented wine-like aromas due to the natural processing.

Washed Processing Method

In addition to natural processing, the washed processing method is also quite common. Many large plantations in various regions use this washed processing method. The general steps are:

1. Pour coffee fruits into water and remove defective beans through flotation, such as immature, overripe, or other debris.
2. Use a pulping machine to remove the outer peel and pulp from the selected coffee fruits. The surface of depulped coffee fruits still has a layer of mucilage attached, so large amounts of clean water are needed to remove the mucilage from the coffee fruit surface.

3. The process of using fermentation to remove mucilage takes approximately 18 hours. Because after fermentation is complete, fermentation bacteria still adhere to the coffee fruit surface, another round of thorough washing with large amounts of clean water is needed. For this step, to obtain 1 kilogram of coffee beans, 40 to 50 kilograms of clean water are consumed. FrontStreet Coffee considers this to be a very large number, which also restricts certain regions from adopting washed processing.
4. The cleaned coffee beans can then be dried. Some regions will directly take them outdoors to air dry. If equipment is available, some processing plants will use machine drying to reduce the coffee moisture content to around 11%. Then hulling machines can be used to remove the inner parchment and silver skin.

Comparison Between Natural and Washed Processing

Among customers who come to FrontStreet Coffee for coffee, the question FrontStreet Coffee is frequently asked is: what's the difference between washed processing and natural processing? FrontStreet Coffee will first explain their differences from the perspective of the coffee beans themselves. FrontStreet Coffee will still use Ethiopian Yirgacheffe beans to explain. Generally, washed Yirgacheffe beans appear greenish-blue, while natural Yirgacheffe beans appear yellowish-green. Therefore, washed beans have more silver skin, while natural beans have less silver skin.

Everyone should not underestimate coffee silver skin. FrontStreet Coffee has discovered during the coffee brewing process that excessive silver skin mixed in the coffee powder significantly affects the coffee flavor, preventing the coffee flavors from being properly extracted. Comparing these two processing methods in terms of coffee flavor, FrontStreet Coffee believes that washed processed coffee beans have brighter flavor profiles, clean taste without impurities, and carry acidity and fruit aromas. Natural processed coffee beans, due to the longer drying time, undergo a slow fermentation process, so when you taste natural beans, they carry a light fermented wine aroma. Additionally, natural beans have more sweetness and acidity than washed beans, with a richer mouthfeel. Therefore, generally, the quality of washed beans is better than that of natural beans.

Kenya K72 Processing Method

The washed processing mentioned above by FrontStreet Coffee is the standard washed processing method. FrontStreet Coffee will now introduce the Kenya K72 processing method, which evolved from washed processing. The K72 processing method differs in the fermentation step from basic washed processing. K72 processing involves, after the first 24 hours of fermentation, changing to fresh clean water and fermenting for another 24 hours, then changing to fresh water again and continuing fermentation for 24 hours, completing three cycles in total. After fermentation is complete, the drying step can begin. Therefore, FrontStreet Coffee has found that the acidity of Kenya coffee beans is more acidic than generally washed processed beans, with refreshing acidity like dark plums and cherry tomatoes.

If you frequently buy coffee beans from FrontStreet Coffee, you'll notice that among FrontStreet Coffee's daily bean series, except for Brazil Red Fruit using semi-natural processing and Indonesia Mandheling using wet hulling, the other five daily beans from FrontStreet Coffee all use washed processing. Because FrontStreet Coffee has always emphasized that washed processing represents the basic flavor of a producing region and is very suitable for beginners who are just starting to drink coffee.

Honey Processing Method

Additionally, FrontStreet Coffee will talk about the honey processing method. Honey processing is a unique creation of Costa Rica. First, coffee fruits undergo washed flotation to remove defective coffee beans. Then the selected coffee fruits are passed through a pulping machine to remove the peel and pulp while retaining the mucilage. They are then taken to raised beds to air dry for about one to two weeks. During this process, the coffee beans are constantly turned to ensure even drying, allowing the coffee beans to fully absorb the sugars from the mucilage.

The raisin honey processing method retains 100% of the mucilage. First, defective beans are removed through flotation, then the selected coffee fruits are directly placed on raised beds to dry for at least three days. Then a hulling machine is used to remove the peel and pulp, retaining the mucilage before proceeding with drying. Because of the sun-drying process without removing mucilage, both raisin honey processed and honey processed coffee beans have very high sweetness. For example, the Costa Rica Musician series coffees like Bach, Chopin, Mozart, and Beethoven available at FrontStreet Coffee all have very high sweetness and rich tropical fruit flavors.

Wet Hulling Method

Honey processing methods are not suitable for rainy weather. Humid and rainy weather like in Indonesia can cause coffee beans to mold. Therefore, Indonesia generally uses the local wet hulling method for coffee bean processing. The general steps are:

1. Remove the peel and pulp from coffee fruits, retaining the parchment and mucilage.
2. Place the processed coffee fruits in water tanks for fermentation to remove mucilage.
3. Then sun-dry the parchment coffee beans for two to three days to reduce moisture content to around 20%.
4. Then hull the parchment and dry the green beans again to reduce moisture content to around 11%, at which point they can be stored in the warehouse.

Using wet hulling to process green beans also brings the disadvantage of unstable bean quality, but from a positive perspective, wet hulling also gives Indonesian coffee its own unique flavor characteristics, such as low acidity and strong herbal spice flavors. Among the five Mandheling coffees available at FrontStreet Coffee, except for Natural Mandheling, all are processed using these methods for green coffee beans.

Anaerobic Fermentation Processing Method

However, with continuous technological advancement, the processing of green coffee beans is also constantly improving. In recent years, anaerobic fermentation processing has emerged, also known as "carbon dioxide maceration" (red wine processing). The process is actually not complicated—it utilizes biotechnology, such as stainless steel tanks that can control oxygen intake, time, temperature, and pH, to place coffee beans in low-oxygen or anaerobic environments, thereby enhancing coffee flavor and sweetness.

For example, Colombia's Flower Moon Night and Rose Valley available at FrontStreet Coffee use anaerobic fermentation processing. Flower Moon Night uses anaerobic natural processing, so its coffee carries strong strawberry flavors and creamy texture. Rose Valley, on the other hand, uses double washed anaerobic enzyme processing, so this variety has more obvious sweet and sour notes, carrying peach flavors. They are very popular among customers at FrontStreet Coffee.

FrontStreet Coffee believes that the coffee market is developing rapidly, with various coffee beans emerging endlessly. Rich processing methods have brought different coffee flavors to every coffee lover, providing everyone with more coffee flavor choices.

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