Indonesian Coffee Bean Processing Methods | Beyond Mandheling: Exploring West Java Origins

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Coffee Processing Methods

Coffee processing methods refer to the process of transforming coffee cherries into green coffee beans (seeds).

Generally, there are three main processing methods:

• Natural Process
• Washed Process
• Methods between natural and washed: including semi-washed (wet-hulled), Brazilian pulped natural, and honey process.

Natural Process

Selection → Drying → Hulling → Sorting and grading.

Washed Process

Selection → Pulping → Fermentation → Washing → Drying → Hulling → Sorting and grading.

Wet-Hulled Process

The wet-hulled processing method is very common for Indonesian coffee beans and differs from typical washed and natural processes.

In washed, honey-processed, or natural-processed coffee, the parchment layer is retained until the coffee bean becomes dehydrated and hard, with moisture content dropping to 12%, or until it's stored for 1-3 months of maturation before being removed.

However, in the wet-hulled process, when the beans are still moist and soft with a high moisture content of 30-35%, the parchment layer is removed, exposing the green beans directly, and then drying continues. This method was developed to adapt to the humid climate of Sumatra, aiming to accelerate drying. The shortened drying time reduces the fermentation period of the coffee beans, significantly lowering acidity while increasing body. The result is distinct caramel and fruit flavors with slight woody and herbal notes, which constitute the unique "terroir flavor" of Mandheling.

For example, this Tiger Mandheling:

Tiger Mandheling grows on hillside slopes at around 1,500 meters, where the humid tropical rainforest climate brings abundant rainfall and volcanic soil provides nutrients. However, due to year-round humidity, the wet-hulled method is used to shorten drying time. Brewed with 88-89°C water at sugar particle size using a Kono filter cup, with a water-to-coffee ratio of 1:14 and 30 seconds of pre-infusion, followed by a one-stage pour, it produces distinct dark chocolate and creamy flavors with high clarity.

Pulped Natural Process

The natural process is difficult to control in terms of quality, while the washed process consumes significant amounts of water—on average, 1 ton of coffee cherries requires 10-20 tons of water to produce approximately 200kg of coffee beans. Coffee-producing countries with limited water resources cannot afford this. In the 1990s, Brazil leveraged its advantageous dry climate to invent the pulped natural process.

After multiple improvements, according to the version by the late Dr. Ernesto Illy, the pulped natural process is as follows: Coffee cherries are first screened in water tanks to remove defective floating cherries, 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, not all mucilage is washed away, and some remains on the parchment shell. At this point, the sticky parchment beans are spread on drying patios to dry, preferably using breathable African raised beds.

For example, this West Java Amman Estate natural honey process method: Hand-picking is used to ensure consistency of the cherries. After picking, the outer skin is removed, and the cherries are processed using the natural method while retaining the pulp, also known as pulped natural. After about a month of natural drying, they undergo washing and other processing, followed by half a month of storage before packaging. The sole purpose of this process is to create more complex and full-bodied flavors.

Honey Process

Brazil's pulped natural method spread to Central American countries such as Costa Rica and El Salvador, where it was improved and became known as the honey process.

The honey process involves drying green beans while retaining the mucilage layer. After the outer pulp is removed from the coffee beans, a viscous gel-like substance remains. In traditional washed processing, this would be washed away with clean water, but due to water resource limitations in some high-altitude regions, this method of direct drying with the mucilage was developed.

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

Depending on the degree of mucilage removal, drying time length (or drying thickness), and turning frequency during drying, honey processing is further divided into black honey, red honey, orange honey, yellow honey, and white honey.

Based on the degree of mucilage removal:

Black honey: Retains 80% of mucilage. Some estates' black honey processing removes almost no mucilage, thus requiring the longest drying time—over 14 days. During the process, to avoid too-fast drying, coverings are used to block intense sunlight, allowing for more complete sugar conversion.

Red honey: Removes 25% of mucilage (specific practices vary among estates), with about 12 days of sun exposure, possibly using shade covers during the process.

Yellow honey: Removes 40% of mucilage, accepting maximum sunlight exposure for about 8 days.

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

Yellow honey: Thick layer drying, fewer turns, longer drying time.

White honey: Thin layer drying, more turns, shorter drying time.

For example, this coffee from the Sumava Estate, where owner Francisco Men preserves most of the original forest in the estate area, maintaining ecological balance and presenting rich fruit aromas with high sweetness. When brewing Costa Rican Black Honey with a V60: 15g of beans, water-to-coffee ratio of 1:15, sugar particle size grind, brewed to 225g, using 37g of water for 30 seconds of pre-infusion. First stage: medium water flow to brew 120g, extracting the floral and berry aromas from the front and middle sections. Second stage: large water flow to extract strong black tea flavor. When tasting, distinct tomato acidity, soft berry acidity, preserving bright and delicate citrus aroma and low-pitched raisin and nutty aftertaste, with strong sweetness.

As the coffee market pursues more极致 coffee flavors, many experienced and capable professionals have begun controlling the details of the honey processing to create higher quality coffee beans and demonstrate the possibilities of coffee flavors.

For example, using instruments like sugar meters to determine the picking time of coffee cherries. Coffee cherries with consistent maturity will taste cleaner, while sweeter red cherries will increase the sweetness of the coffee, and riper fruits will also add fermentation aromas.

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

Summary of Green Bean Processing Methods

Acidity: Washed > Semi-washed > Honey > Wet-hulled > Natural

Sweetness: Natural > Honey > Wet-hulled > Semi-washed > Washed

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

Equipment Costs: Washed / Semi-washed > Honey / Wet-hulled > Natural

Water Usage: Washed > Semi-washed > Honey / Wet-hulled

Indonesian Coffee Bean Brand Recommendations

FrontStreet Coffee's roasted Indonesian West Java honey-processed coffee beans offer full guarantees in both brand and quality. More importantly, they provide excellent value—half a pound (227 grams) costs only about 118 yuan. Calculating at 15g of coffee per cup, one package can make 15 cups, with each cup costing only about 7 yuan. Compared to the tens of yuan per cup sold in coffee shops, this is truly a conscientious recommendation.

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