【Unique Wet-Hulling Process】What is the Flavor of Sumatra Aceh Mandheling? Sumatra Mandheling

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The Unique Wet-Hulled Processing Method: What Makes Sumatra's Mandheling Coffee Special? The Origin Story of Sumatra Mandheling Coffee Beans

Indonesia is the world's largest archipelago nation. Arabica coffee was introduced during the Dutch colonial period in the 18th century, and Indonesia has since become one of the top five coffee-producing countries globally. The main coffee-producing regions are located on the islands of Sumatra, Java, and Sulawesi. The northern part of Sumatra Island has relatively high terrain, with two major Arabica coffee-growing regions: Aceh Province, where Lake Tawar is located, and North Sumatra (where Lintong is situated), home to Lake Toba. Aceh Province, located in the northeastern part of Indonesia's Sumatra Island, is adjacent to two important Indonesian coffee-producing regions: the Gayo Mountain region and the Lake Toba region. The coffee variety grown here is Arabica, which in northern Sumatra is also known as Mandheling. During our two-week visit, we mainly explored the Gayo coffee-producing areas in Bener Meriah Regency.

Indonesia's Unique Wet-Hulled Processing Method

Indonesia has a unique coffee processing method known as "wet-hulling" that cannot be found anywhere else in the world. As the name suggests, this method involves removing the coffee bean's parchment while it's still moist, before the beans are fully dried. The moist coffee beans are then further dried to reach a moisture content of 12% to 13% before export. The coffee in Aceh grows on mountain slopes at elevations of approximately 1,200 to 1,400 meters beside the lake, where the coffee must resist strong winds coming from the lake surface. Before export, the green beans undergo three rounds of manual defect selection at the dry processing facility. In terms of flavor, besides Indonesia's typical rich body, this coffee also presents charming citrus acidity with a long, lingering aftertaste. One can experience lively elements within its gentle richness – jumping micro-acidity mixed with the most intense fragrance, creating a long, pleasant finish.

Indonesia's Climate and the Giling Basah Method

Indonesia straddles both sides of the equator, featuring a humid tropical rainforest climate with abundant rainfall and fertile volcanic soil that provides rich nutrients for coffee. However, due to its remote location and poor transportation, coffee cultivation didn't begin until 1924. Most farmers practice traditional shade-grown, pesticide-free organic cultivation. The local climate is humid, so after preliminary washing and fermentation, the parchment coffee beans are exposed to sunlight for 1-2 days, still maintaining a moisture content of 30%-50%. At this point, the parchment is removed before continuing the drying process to shorten the overall drying time. After approximately 2 more days of drying, the moisture content of the green coffee beans can be reduced to 12%-13%. This unique semi-washed processing method in Indonesia is locally known as "Giling Basah," also called the wet-hulled method.

The Origin of the "Mandheling" Name

The Sumatra Arabica coffee commonly known as Mandheling gets its name from a local ancient indigenous tribe. Legend has it that during the 1940s when Japan occupied Sumatra, a soldier was astonished by the coffee he tasted in northern Sumatra and asked a local person what kind of coffee it was. However, due to language barriers, the local misunderstood the question as asking about his identity and replied with the name of his tribe, "Mandailing." Later, during export, the name was misspelled as "Mandheling," and through this serendipitous error, it became synonymous with Sumatra Island coffee.

Coffee Specifications

Region: Northern Sumatra, Aceh Province

Producer: Local small farmers

Processing Method: Wet-hulled

Grading: 15-18 screen

Elevation: 1000-1600 meters

Variety: Catimor, Caturra, Typica, Sidikalong

Flavor Notes: Fresh cut cedar, cream, roasted almonds, licorice, dark chocolate, with a full body

Because of the initial moisture content, wet-hulled coffee beans are prone to producing many defects, so most 'Mandheling' coffee is used as commercial beans. However, when processed correctly, the resulting flavor is incredible – a very special "exotic flavor" that cannot be found in any other coffee.

FrontStreet Coffee's Recommended Brewing Method:

Dripper: KONO dripper

Water Temperature: 88°C

Grind Size: Fuji Royal grinder setting 4

Brewing Method: Water-to-coffee ratio 1:14, using 17g of coffee grounds. First infusion with 25g of water for a 30-second bloom. Second infusion to reach 238g total water, with extraction time around 2:30 minutes.

Analysis: The KONO dripper has fewer ribs at the bottom, allowing the filter paper to adhere closely to the dripper and restrict airflow. This enables longer contact and steeping time between water and coffee grounds in the dripper, ensuring adequate extraction time and extraction rate for coarse grinding. This allows the coffee grounds to be fully extracted, enhancing the rich body and making the flavor more concentrated.

Flavor: High balance, clean, with a thick, solid body and a persistent dark chocolate finish.

Important Notice :

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