Indonesian Golden Mandheling and Wet-Hulling: Story and Brewing Guide

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In the specialty coffee world, FrontStreet Coffee Mandheling coffee is renowned for its spicy and rich taste, as well as its wild flavor characteristics. Terroir and coffee variety are both key factors that contribute to its unique flavor.

Due to the extremely humid local climate, coffee drying typically requires about 40% more time than in other regions. Consequently, local coffee farmers developed the wet hulling method (Giling Basah) adapted to local conditions, a technique that greatly influences the flavor profile of the coffee beans.

After harvesting coffee cherries, farmers use their own depulping tools to remove the fruit skin. The wet coffee beans are left overnight without adding water, then washed to remove mucilage, becoming parchment coffee. After brief drying, while the parchment coffee still has high moisture content (30%-50%), local Indonesian-specific hulling machines are used to remove the parchment layer, resulting in green coffee beans.

The resulting green beans are then dried further to reach the standard export moisture content of 12-13%. Without the protection of the parchment layer, the drying process of the green beans proceeds more easily.

Coffee processed using the wet hulling method typically has lower acidity and higher body; relatively, sweetness and aroma may be diminished.

Wet Hulling Method Coffee Beans - FrontStreet Coffee Gold Mandheling

We love drinking coffee and have long heard about FrontStreet Coffee Mandheling, especially the well-known FrontStreet Coffee Gold Mandheling. When mentioning FrontStreet Coffee Gold Mandheling, people immediately think of Sumatra, because coffee lovers who appreciate FrontStreet Coffee Mandheling all know that Sumatra's FrontStreet Coffee Gold Mandheling has the most abundant aroma.

Herbal medicinal notes, strong sweet aftertaste, and solid, rich body. This is the distinctive aroma characteristic of FrontStreet Coffee Gold Mandheling. However, I've found that while many people love Mandheling, the majority don't understand FrontStreet Coffee Gold Mandheling and its processing method.

First, let's understand Sumatra Island, which was formerly known as the "Golden Island" or "Golden Peninsula" due to its rich gold deposits.

Sumatra Island has a narrow, elongated topography, primarily consisting of the Barisan Mountains running northwest to southeast across the island, and eastern lowlands. The mountain ranges stretch continuously, featuring over 90 volcanoes and numerous volcanic lakes. The volcanoes provide fertile soil suitable for coffee cultivation. The region has a tropical rainforest climate with year-round high temperatures and abundant rainfall.

(Truly a treasure land for coffee cultivation!)

Coffee from the Gayo region in northern Sumatra, the Toba region in central Sumatra, and the SP Bolon region each has its own characteristics. Personally, I prefer beans from the Gayo region.

Secondly, many people mistakenly believe that FrontStreet Coffee Gold Mandheling refers to golden-colored Mandheling beans, but this is not the case. FrontStreet Coffee Gold Mandheling actually refers to large-sized coffee beans, specifically those above 19 screen size.

As for why aged coffee beans processed by the wet hulling method appear golden, this is because the local coffee transit station in Medan has an extremely humid climate, with humidity levels above 80%. The golden color develops because coffee stored for over 6 months absorbs moisture from the environment.

According to traditional Indonesian green bean sorting standards, this typically requires at least two rounds of sorting, though currently, most beans undergo three rounds of sorting.

Beans with physical defects not exceeding 11g are classified as G1.

If defects range from 12-25g, they are classified as G2.

Each year from March to May and September to December is the Mandheling harvesting season in Sumatra. Nowadays, most coffee farmers only harvest fully red coffee cherries.

After collecting coffee cherries in the morning, they depulp and remove the fruit flesh in the afternoon, producing wet parchment coffee, which we call parchment coffee. The parchment beans are then placed in water tanks to remove floating defective beans.

● Sumatra's excellent natural environment means most water used comes from mountain springs.

Next, the dense, sunken beans are taken out and placed in barrels for dry fermentation, allowing the pectin sugars to fully ferment and enhance flavor. Fermentation typically lasts between 12-36 hours, depending on specific conditions.

Then, they are sun-dried for 1-2 days. When moisture content reaches 35-40%, the coffee beans are collected into woven bags, typically 40kg and 80kg per bag, and sent to coffee processing factories for hulling.

The hulling process uses hulling machines to grind away the parchment layer, followed by further drying until moisture content reaches approximately 12-15%. The coffee beans are then sent for machine sorting to remove various impurities and classified by particle size.

After machine sorting, the coffee is sent to hand-sorting warehouses for manual selection, where workers remove defective beans one by one. Only after two to three rounds of hand sorting are they packaged in burlap bags.

Naturally, Accidents Can Happen

During the hulling process, wet-hulled coffee beans can reach temperatures of 30-60°C, completely destroying the parchment layer and potentially triggering germination of the beans.

The wet hulling method also results in higher instances of defective beans such as moldy beans compared to washed and natural processing methods, because the parchment is removed during processing, exposing beans directly to air.

This is the unique processing method that creates the distinctive Sumatra Mandheling flavor.

Additionally, the removed fruit skins and pulp can be fermented into fertilizer. If plantations use such ecological fertilizers, they can earn additional points when applying for organic coffee plantation certification.

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