Introduction to Sumatra Tiger Mandheling | The Origin of Indonesia's Sumatra Tiger Mandheling Name

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FrontStreet Coffee - Introduction to Aceh Sumatra Tiger Mandheling

Indonesia is an archipelagic country with major growing areas located on three islands: Sumatra, Java, and Sulawesi. The northern part of Sumatra Island has relatively high terrain, with the Aceh Province where Lake Tawa is located and North Sumatra where Lake Toba is situated being the main Arabica coffee growing regions. Lake Tawa is located in the Gayo Mountains in northern Aceh, Sumatra. Indonesia, which straddles both sides of the equator, has abundant rainfall in its humid tropical rainforest climate, and the fertile volcanic soil provides rich nutrients for coffee. However, due to its remote location and inconvenient transportation, coffee cultivation did not begin until 1924, mostly using traditional shade-grown, pesticide-free organic cultivation methods.

In Aceh, coffee ranks as the second largest export economic crop in the region. It is estimated that there are about 60,000 small-scale coffee farmers locally, with each owning about 1-2 hectares of coffee cultivation land. The traditional Indonesian coffee trade method involves a multi-point supply chain, starting from farmers, passing through multiple layers of middlemen, before gradually accumulating large quantities of export goods. In Indonesia's coffee trading system, direct trade where a single window collects goods from farmers and arranges for export is quite rare locally.

02 | Processing Method

Wet hulling, also known as Wet Hulling, is called Giling Basah in the local language and is a traditional Indonesian coffee processing method. Judging by name alone, wet hulling appears very similar to wet processing (washed processing), however, the cupping flavors of these two processing methods are completely different. Coffee processed by wet hulling is typically rich and intense, with a very distinct personality.

Wet Hulling Processing Steps

① Remove the skin and pulp, keeping the parchment and mucilage

② Ferment in water tanks

③ Wash away the mucilage

④ Sun-dry with parchment for 2-3 days until moisture content reaches 20-24%

⑤ Hull the parchment

⑥ Dry the green beans to 12-13% moisture content

⑦ Prepare for export

Why Use Wet Hulling?

a. Climate Reasons

The tradition of using wet hulling in Indonesia stems from local weather conditions. Indonesia's annual humidity ranges between 70-90%, with continuous typhoons, and in some regions, annual rainfall can reach as much as 2,000mm. Considering that green beans are most vulnerable to rain, how does Indonesia overcome such harsh weather conditions to produce rich and mellow Mandheling coffee? That is through wet hulling.

Under tropical climate conditions, coffee takes an average of 2-3 weeks to dry. In Indonesia's humid climate, drying coffee becomes a significant problem. Coffee drying requires a longer time, during which the coffee maintains high humidity, making it easier for bacteria to penetrate the green beans.

In regular washed processing, the drying process is carried out with parchment on to protect the green beans from external damage to some extent. However, we can note that wet hulling removes the parchment for the final drying step, allowing direct sunlight to hit the surface of the green beans, causing them to dry quickly - 2-3 times faster than washed processing.

b. Economic Benefits

Dutch colonizers first introduced coffee to Indonesia in the 17th century. These colonists pursued more and faster economic returns, and wet hulling greatly reduced the time spent on farms and significantly lowered labor costs. This aligns with the investor mindset of pursuing quick profits and reducing costs, which is another reason promoting the wet hulling method.

c. Defects and Kuku Kambing (Goat Hoof Beans)

When wet hulling removes the parchment, the coffee's moisture content is still as high as 20-24%, whereas in regular processing methods, coffee moisture content is reduced to 10-12% before hulling. In a "semi-dry" state, the parchment tends to adhere to the surface of the green beans, making hulling more difficult than with "fully dry" beans, requiring greater friction during the hulling process.

On the other hand, "semi-dry" green beans are very fragile at this stage, with hardness far inferior to "fully dry" beans, so the beans are more easily bruised, forming small cracks. This is what we commonly call horseshoe or goat hoof beans (locally known as kuku kambing).

The ultra-fast processing speed of wet hulling also results in higher defect rates in Mandheling coffee. Processing plants arrange for employees to conduct manual defect sorting, typically including DP (double picking) and TP (triple picking). Mandheling that undergoes triple picking will have a lower defect rate than double picking.

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