What is Indonesian Wet Hulling? What is Pulped Natural? What is Honey Processing?

Coffee Processing Methods: Understanding the Journey from Cherry to Bean

FrontStreet Coffee frequently explains in our articles that coffee processing methods refer to the process of transforming coffee cherries into raw coffee beans (seeds). Generally, there are three processing methods: natural process, washed process, and intermediate processing methods between natural and washed, including semi-washed (wet-hulling), Brazilian pulped natural, and honey process.

Natural Process: Bean Selection - Drying - Hulling - Sorting and Grading

Washed Process: Bean Selection - Pulp Removal - Fermentation - Washing - Drying - Hulling - Sorting and Grading

Wet-Hulling Process

The wet-hulling processing method is very common in Indonesia and differs from typical washed and natural processes.

In washed, honey, or natural processed beans, the parchment is retained until the bean body dehydrates and hardens, with moisture content dropping to 12%, or until sealed and stored for 1-3 months of maturation before being removed.

However, wet-hulling removes the parchment while the bean body is still moist and soft, with moisture content as high as 30-35%, exposing the raw bean surface directly before continuing to dry. This method was developed in response to the humid climate of Indonesia's Sumatra island, aiming to accelerate drying. Although the drying process is shortened, the fermentation period of the coffee beans is also reduced, significantly decreasing acidity while increasing body. Furthermore, because the beans are exposed to humid air, herbal and woody flavors develop. After roasting, the coffee exhibits distinct caramel and fruit aromas—this is the unique "terroir" character of Mandheling.

For example, this FrontStreet Coffee Golden Mandheling coffee bean uses wet-hulled processing and undergoes three manual selections plus one mechanical selection, minimizing defect rates to ensure the coffee beans taste both clean and pure.

FrontStreet Coffee's Golden Mandheling grows on slopes around 1,500 meters above sea level. The humid tropical rainforest climate brings abundant rainfall, while volcanic soil provides nutrients. However, due to persistent humidity, the wet-hulling method is used to shorten drying time. When brewed with 88-89°C water, using sugar-sized particles, a Kono dripper, and a 1:15 coffee-to-water ratio, with a 30-second bloom followed by single-stage pouring, it produces distinct dark chocolate and cream flavors with high clarity.

Pulped Natural

Natural processing is difficult to control in terms of quality, while washed processing consumes significant water—averaging 10-20 tons of water per ton of coffee cherries to produce approximately 200 kilograms of coffee beans, making it unaffordable for coffee-producing countries with limited water resources. In the 1990s, Brazil leveraged its advantageous dry climate to invent the pulped natural method.

After multiple improvements, according to the version by the late Dr. Ernesto Illy, the pulped natural process is: coffee cherries are first screened in water tanks to remove defective floating fruits, then the skin, pulp, and part of the mucilage layer are removed, followed by one hour of washing. Due to the short soaking and fermentation time, the mucilage is not completely washed away, leaving residual mucilage on the parchment. At this point, the sticky parchment beans are spread on drying patios to dry, preferably using well-ventilated African raised beds.

For example, this FrontStreet Coffee West Java Amenity Estate uses natural honey processing. Manual harvesting ensures fruit stability. After removing the outer skin, natural processing is performed while retaining the pulp—also known as pulped natural. After approximately one month of natural drying, cleaning and other processes are performed, followed by storing the beans for about half a month before packaging. The sole purpose of this process is to create more complex and full-bodied flavors.

Honey Process

After Brazil's pulped natural method spread to Central American countries like Costa Rica and El Salvador, it was improved and became known as honey processing.

The honey process involves sun-drying raw beans while they still have mucilage attached. After removing the outer pulp from coffee beans, a layer of viscous gelatinous substance remains. In traditional washed processing, this would be washed away with clean water. However, due to water resource limitations in some high-altitude growing regions, this method of drying directly with the mucilage attached was developed.

Honey processed coffee has higher sweetness and sugar content than washed coffee, with relatively higher body (premise: compared under the same roast level).

Based on the thickness of mucilage removal, sun-drying duration (or drying thickness), and turning frequency during drying, honey processing is further categorized into black honey, red honey, orange honey, yellow honey, and white honey.

Based on mucilage removal thickness:

Black Honey: Removes 80% of mucilage (some estates remove almost no mucilage for black honey processing), making it the longest drying process, requiring more than 14 days. During the process, to avoid drying too quickly, coverings are used to block excessive sunlight, allowing for more complete sugar conversion.

Red Honey: Removes 25% of mucilage (specific practices vary among estates), sun-drying for about 12 days, during which shade covers may also be used.

Yellow Honey: Removes 40% of mucilage, accepting maximum light exposure for drying, lasting about 8 days.

Some growing regions and estates distinguish based on drying thickness and turning frequency. For example, yellow and white honey both retain 20-30% mucilage:

Yellow Honey: Thick-layer drying, fewer turns, longer drying time;

White Honey: Thin-layer drying, more turns, shorter drying time.

For example, this FrontStreet Coffee Costa Rica Sumava Estate Black Honey Caturra from Sumava Estate, where owner Francisco Men preserves most of the original forest in the plantation area, maintaining ecological balance, resulting in coffee beans with rich fruity aromas and high sweetness. When brewing FrontStreet Coffee Costa Rica Black Honey Caturra with a V60, using 15g of beans, 1:15 coffee-to-water ratio, sugar-sized grind, brewing to 225g total, with 37g water for a 30-second bloom, the first stage uses medium water flow to pour 120g, extracting early and mid-stage floral and berry aromas, while the second stage uses large water flow to extract strong tea-like flavors. When tasting, distinct tomato acidity is present, with soft berry acidity, retaining bright and delicate citrus aromas and low-pitched raisin and nutty aftertaste, with strong sweetness.

As the coffee market pursues more extreme coffee flavors, many experienced and capable practitioners have begun to control the details of the honey processing process to produce higher quality coffee beans and showcase the possibilities of coffee flavors. For example, using instruments like Brix meters to determine the optimal harvesting time for coffee cherries. Coffee with uniform maturity tastes cleaner, while sweeter red cherries also increase the coffee's sweetness, and riper fruits add fermentation aromas.

The honey process retains the cleanliness of washed processing, although not as bright as washed processing, but it increases sweetness and caramel notes.

Summary of Raw Bean Processing Characteristics

Finally, let's summarize the characteristics of various raw bean processing methods:

Acidity: Washed > Semi-washed > Honey Process > Wet-hulling > Natural

Sweetness: Natural > Honey Process > Wet-hulling > Semi-washed > Washed

Production Risk: Wet-hulling / Natural > Washed / Honey Process > Semi-washed

Equipment Cost: Washed / Semi-washed > Honey Process / Wet-hulling > Natural

Water Usage: Washed > Semi-washed > Honey Process / Wet-hulling

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