What's the Difference in Taste and Flavor Between Washed and Natural Coffee Beans? An Introduction to Flavor Variations

Natural vs. Washed Coffee Processing: Understanding the Differences

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Among coffee bean processing methods, the most common are natural processing and washed processing. So what exactly are the differences between these coffee beans processed by different methods? FrontStreet Coffee believes that in the same growing region, washed processing represents the base flavor of a coffee bean, while natural and honey processes build upon this base flavor by adding aroma and some sweetness. Therefore, FrontStreet Coffee thinks the difference between these two coffee processing methods is: washed coffee beans highlight the main flavor, while natural coffee beans soften the main flavor and increase aroma and sweetness, making a cup of coffee more complex. Why is this?

The difference from the washed process lies in the drying stage where the pulp participates in drying, while washed processing has no pulp involvement, so the washed process naturally presents the bean's fundamental taste. Through long-term cupping and tasting, FrontStreet Coffee has found that naturally processed coffee beans offer richer, fuller flavors, while washed coffee beans are cleaner, highlighting the bright acidity of coffee. FrontStreet Coffee will detail the differences between these two coffee processing methods below.

Raw Bean Appearance

FrontStreet Coffee observed the appearance of washed and natural coffee beans in their raw state and found very distinct contrasts. Washed coffee beans have a distinctly bluish-green color, while natural coffee beans have a more yellowish appearance. (As shown in the picture below)

Roasting Details

There are also differences when roasting washed and natural coffee beans. FrontStreet Coffee's roaster explains that washed coffee beans have a slightly higher moisture content than naturally processed beans. Therefore, when comparing the roasting of these two processing methods, roasting washed beans requires extending the dehydration time.

The dehydration stage generally refers to the period from when raw coffee beans enter the roaster until the beans complete dehydration and turn yellow. Throughout the entire coffee roasting process, moisture is being removed, but most of the water from the raw beans is removed during this stage.

During the dehydration stage, the structure of raw beans is most complete and most resistant to heating. It's necessary to use sufficient heat to warm the coffee beans during this stage, creating a larger temperature difference between the bean surface and core, allowing the coffee beans to quickly absorb heat and thereby build up sufficient thermal potential energy and pressure in the bean core.

Because as coffee roasting progresses, the structure of coffee beans becomes increasingly fragile, yet the formation of flavor compounds requires sufficient heat. If enough thermal potential energy isn't established in the early stages of roasting, adding heat later will easily cause the bean surface to burn. Of course, during the dehydration stage, even when aiming for a larger temperature rise rate, moderation must be maintained, otherwise the beans can also be scorched.

The image above shows washed roasted beans

The image above shows natural roasted beans

Roasted Bean Appearance

FrontStreet Coffee observed that in their roasted state, washed coffee beans clearly have more silver skin than natural beans.

FrontStreet Coffee's roasting master explains that during the roasting process, the silver skin at the center line of coffee beans is the most difficult to remove. Because the outer silver skin of natural beans connects in one piece, it's easier to remove along with the silver skin at the center line, so after roasting, the silver skin on natural roasted beans comes off very cleanly. Washed beans are the opposite - because there's almost no connected silver skin on the outer layer, the silver skin in the center line crack cannot be easily removed and instead remains after roasting. This is why roasted washed beans show more silver skin while natural beans show less.

Brewing Details

When brewing lightly roasted washed coffee beans, more attention needs to be paid to the amount of silver skin in the coffee. (The degree of roast also affects the amount of silver skin - the darker the roast, the more silver skin is removed). Du Jianing, the 2019 World Coffee Brewing Champion, removes silver skin through double grinding to reduce its impact on coffee.

Natural Process (Dry process)

The natural process is the oldest and most primitive coffee processing method. Compared to the washed process, coffee processed by this drying method is also called "natural coffee" or "sun-dried coffee." The harvested coffee cherries are directly exposed to sunlight for about two to four weeks. This method is typically used in countries with distinct dry and wet seasons.

Natural Process Steps

1. Harvest ripe coffee cherries
2. Initial sorting to remove impurities and defective beans
3. Floating bean selection: Pour coffee cherries into a water tank. Ripe, full cherries will sink to the bottom, while unripe or damaged cherries will float to the surface.
4. Sun drying: Remove the ripe coffee cherries from the bottom of the tank and spread them on a drying patio for sun drying, reducing moisture content from 70% to about 10-12%. The cherries need to be turned several times daily to ensure even drying, and covered at night to avoid moisture absorption.
5. Removal of outer shell: After about two to four weeks of sun exposure, the outer layer of coffee seeds becomes dry and hard. At this point, a hulling machine is used to remove the outer shell to complete the process.
6. Packaging and shipping: The hulled coffee beans are packaged in bags, which is what we generally call green beans. Finally, through different roasting processes and brewing variations, they can present millions of flavor changes in coffee.

Advantages and Disadvantages of Natural Process

Advantages: The process is simple and doesn't require much investment in tools and equipment. Besides the step of removing floating beans, it doesn't require water, making it relatively low-cost. It's widely used in areas with limited water resources and less wealthy regions.

Disadvantages:

1. Requires sufficient space for sun exposure, and because coffee beans must be placed outdoors, fallen leaves, insects, and other impurities often get mixed in.
2. The intensity of daily sunlight varies, making it difficult to control the drying degree of coffee beans.
3. Requires more manpower to turn the beans regularly to ensure no mold or rot occurs.

Today, there are improved versions like the "African raised bed" design, where elevated netting avoids ground moisture and soil impurities, and air circulation allows coffee cherries to be more ventilated and dry evenly.

Washed Process (Wet process)

The washed process technique was invented by the Dutch in the 18th century. Because some countries experience frequent rain and high humidity, making the natural process impossible to implement, although the process is relatively more complicated, it has become the most widely used processing method today. The biggest difference from the natural process is the use of fermentation to remove the mucilage layer.

Washed Process Steps

The first three steps are the same as the natural process (1. Harvest ripe coffee cherries 2. Initial sorting to remove impurities and defective beans 3. Floating bean selection)

4. Removal of skin and pulp: Good coffee cherries are put into a pulping machine to remove the outer skin and pulp, leaving the seeds (coffee beans).
5. Fermentation to remove mucilage: Coffee seeds covered with a layer of mucilage are placed in fermentation tanks, where biological processing uses fermentation bacteria to dissolve the mucilage.
6. Washing to remove impurities: Since fermentation bacteria remain on the coffee beans, the beans need to be sent to washing pools for cleaning and a second sorting (defective beans will float on the water surface). This step requires consuming large amounts of clean water to ensure thorough cleaning.
7. Coffee bean drying: Usually machines (or sun drying) are used to dry the coffee cherries, reducing moisture content to 10-14%.
8. Removal of parchment and silver skin: Finally, a hulling machine is used to remove the remaining parchment and silver skin, completing the processing. The green beans can then be packaged and shipped!

Advantages and Disadvantages of Washed Process

Advantages: Coffee beans have fewer impurities and more complete appearance. Since the pulp of coffee cherries is removed at the beginning, there's no need to worry about mold issues, resulting in more stable overall quality.

Disadvantages: The washed process is complex and tedious, and requires large amounts of water, making it relatively more expensive than the natural process. It's less commonly used in water-scarce regions.

Flavor Differences Between Washed and Natural Coffee Beans

The natural process is the oldest processing method, simpler than the washed process. Although natural beans have uneven appearance and significant color differences, because the coffee beans mature naturally inside the fruit without interference from external environments, naturally processed coffee beans have more intense flavors, with wine-like fermentation notes and sweetness.

The washed process harvests cherries when they turn red, while the natural process lets them continue to turn purple and black until they fall off naturally. Then the cherries are spread in the sun for several weeks. After the pulp dries, the seeds separate naturally, and machines or manual labor are used to grind away the hardened pulp to extract the seeds. The importance of late harvesting lies in allowing the seeds to fully absorb the aroma and sweetness of the pulp. After sun exposure, the flavors are more complex than washed beans, with better body. Washed beans develop acidic substances during fermentation in the fermentation tanks, so they typically have bright, clean acidity. Yemen Mocha, Ethiopia Harar, and some Brazilian estate beans belong to this method.

Which Processing Method Produces Better Coffee Beans?

In daily cupping and brewing, FrontStreet Coffee believes that washed processing offers stable quality and clean taste, with better aromatic acidity and brightness; while naturally processed coffee carries the sweet and sour notes of tropical fruits, preserves the natural richness of coffee beans, offers rich flavor layers, and sometimes even has a hint of wine aroma.

However, different people have different preferences for flavors and mouthfeel, so before launching the Panama Geisha "Flor" coffee, FrontStreet Coffee also roasted two different processing methods of Geisha "Flor" for comparison.

Natural Panama Geisha "Flor"

Roaster: Yangjia 800N semi-direct heat (550g batch size)

Preheat roaster to 200°C, load beans, adjust heat to 160 after 30 seconds, open damper to 3. Return temperature at 1'38", maintain heat; at 140°C keep heat at 160°C, open damper to 4. Turn yellow at 5'40", grassy smell disappears, enter dehydration stage. At 168°C, reduce heat to 140°C, keep damper at 4. At 178°C, adjust heat to 110, damper unchanged.

Dehydration complete at 9'00", wrinkles and black spots appear on bean surface, toast smell turns to coffee aroma, prelude to first crack. At this point, pay attention to listen for first crack sounds. First crack starts at 9'18", open damper fully to 5, heat unchanged. Development time after first crack is 1'30", discharge at 193°C.

Washed Geisha "Flor"

Roaster: Yangjia 800N semi-direct heat (550g batch size)

Preheat roaster to 200°C, load beans, adjust heat to 160 after 30 seconds, open damper to 3. Return temperature at 1'31", maintain heat; turn yellow at 4'50", grassy smell disappears, enter dehydration stage. At 165°C, reduce heat to 130°C, keep damper at 4.

Dehydration complete at 7'50", wrinkles and black spots appear on bean surface, toast smell turns to coffee aroma, prelude to first crack. At this point, pay attention to listen for first crack sounds. First crack starts at 8'31", open damper fully to 5, adjust heat to 70°C. Development time after first crack is 1'28", discharge at 193°C.

Pour-over Parameters for Natural Geisha "Flor" Coffee

Coffee beans: 15 grams
Coffee-to-water ratio: 1:15
Water temperature: 91°C
Grind size: Fine sugar (EK43s setting 10)
Pouring technique: Three-stage pour

30g water for bloom, 30 seconds. Slowly pour with small water flow to 125g in segments. Wait for water level to drop until the coffee bed is about to be exposed, then pour again to 225g and stop pouring. Move the filter cup when the water level drops until the coffee bed is about to be exposed. Extraction time (starting from bloom) is 2'00".

Flavor: Tea-like, fermented wine aroma, and spice notes on entry. Rich mouthfeel. As temperature slightly decreases, sweet and sour fruit flavors of citrus, plum, and sweet orange appear. Honey sweetness in the aftertaste.

Pour-over Parameters for Washed Geisha "Flor" Coffee

Coffee beans: 15 grams
Coffee-to-water ratio: 1:15
Water temperature: 91°C
Grind size: Fine sugar (EK43s setting 10)
Pouring technique: Three-stage pour

30g water for bloom, 30 seconds. Slowly pour with small water flow to 125g in segments. Wait for water level to drop until the coffee bed is about to be exposed, then pour again to 225g and stop pouring. Move the filter cup when the water level drops until the coffee bed is about to be exposed. Extraction time (starting from bloom) is 2'00".

Flavor: Jasmine fragrance, citrus, and green tea notes on entry. Sugarcane sweetness in aftertaste. Clean and transparent mouthfeel with a relatively refreshing feeling.

By trying comparisons of beans with different processing methods, FrontStreet Coffee believes that even the same bean will bring different flavors with different processing methods. Naturally processed beans will carry distinct fermented fruit aromas, have richer layers, and a richer mouthfeel; while washed processed beans typically have bright fruit acidity, with cleaner and more transparent flavors that allow clear perception of the bean's characteristics, making them very refreshing. FrontStreet Coffee often conducts comparisons of different coffee regions or different processing methods, hoping to provide references for everyone to choose based on their own preferences.

Important Notice :

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