Sumatran Coffee: What Makes It Different and How to Brew It

There is no coffee quite like Sumatran coffee. Pick up a bag for the first time and you will notice immediately that these beans look different: green tinged, irregular in shape, often slightly bluish compared to the uniform brown of most roasted coffee. And when you brew them? The cup is unlike anything an Ethiopian natural or a washed Colombian can produce. Deep, earthy, heavy on the palate with a low, rolling acidity that makes it feel substantial rather than bright. It is divisive in the best possible way.

Sumatra is part of Indonesia, the world's fourth largest coffee producing country, and it has been growing Arabica coffee in its volcanic highlands since Dutch colonists introduced cultivation in the 17th century. The most famous growing regions sit in the north and west of the island: the Aceh and North Sumatra provinces, particularly around Lake Toba and the Gayo highlands. These areas combine altitude (1,200 to 1,700 metres), rich volcanic soil and a consistently humid climate. All of those factors contribute to the coffee's character, but none of them alone explains what makes Sumatran coffee taste the way it does. That comes from the processing.

Wet Hulling: The Processing Method That Defines Sumatran Coffee

Most coffee is processed either as a washed coffee (the fruit is removed before drying) or as a natural (dried with the fruit still on). Sumatran coffee uses neither of these conventional routes. Instead, it goes through a local method called Giling Basah, which translates roughly as wet hulling.

Here is how it works. After the coffee cherries are picked, they are depulped to remove the outer fruit skin. But unlike washed coffees, the beans are not left to dry fully at this stage. Instead, they are hulled while still at a very high moisture content, typically 30 to 50 percent. This is unusual. In most of the world, coffee is dried down to around 11 to 12 percent moisture before the outer parchment layer is removed. In Sumatra, that parchment comes off while the bean is still essentially wet.

The beans then continue drying, but without their protective parchment layer. The result is a coffee with a distinctive bluish green colour in the green bean stage and, once roasted, a heavy, earthy, often slightly musty character that you will not find anywhere else. Some people describe it as forest floor, cedar, dark chocolate and tobacco. It sounds like it should be off putting, but for those who love it, it is deeply compelling.

The Main Sumatran Growing Regions and What They Taste Like

Not all Sumatran coffee is the same. The island is large and growing conditions vary considerably between regions. The three names you are most likely to see on UK speciality bags are Mandheling, Aceh Gayo and Lintong.

Mandheling is probably the most famous. It comes from around Padang Sidempuan in North Sumatra and is typically full bodied, low in acidity, with chocolate and earthy notes. When roasted to medium or medium dark, it produces a serious, grown up cup that holds up beautifully to milk but is equally rewarding black.

Aceh Gayo comes from the Gayo highlands in Aceh province at altitudes above 1,400 metres. It tends to be slightly cleaner and more complex than Mandheling, with herbal notes and a pleasant syrupy mouthfeel. Gayo coffee has also become known for its organic certification: many small producers in the region have transitioned to fully organic farming.

Lintong comes from the region around Lake Toba and sits somewhere between the two in terms of character. It is earthy and bold but with a slightly brighter finish than Mandheling. If you want to explore Sumatran coffee without going full intensity from the start, Lintong is a good introduction.

How to Brew Sumatran Coffee at Home

Because Sumatran coffee is naturally heavy and full bodied, it works best with brewing methods that complement rather than fight that character. French press is an excellent choice: the metal filter lets the oils into the cup and adds to the richness. Moka pot produces a concentrated, intense version that is outstanding as a base for long black coffee.

Pour over can work beautifully with Sumatran coffee if you want a slightly cleaner version of its character. Use a coarser grind than you might normally, and slightly lower your water temperature to around 91 to 93 degrees Celsius to avoid over extracting the earthier compounds.

For espresso, Sumatran coffee is a classic component in many roaster blends. Its low acidity and heavy body add depth and sweetness that balance brighter, more acidic origins. On its own as an espresso, it produces a thick, chocolatey, low acid shot that people who find bright espresso overwhelming often love.

A good starting ratio for French press is 1 gram of coffee to 15 grams of water (around 60 grams per litre). For pour over, try 1 to 16 (roughly 62 grams per litre). Sumatran coffee can handle a medium dark roast well, so do not feel you need to hunt for a light roast version, though those exist and are interesting in their own right.

Is Sumatran Coffee Right for You?

Sumatran coffee is one of those origins that people tend to either love immediately or need a few attempts to appreciate. If you find bright, acidic Ethiopian or Kenyan coffees too sharp or too fruit forward, Sumatran is worth trying. Its low acidity, heavy mouthfeel and earthy character sit at the opposite end of the coffee spectrum and appeal to people who want something bold and grounding rather than bright and floral.

On the other hand, if you are sensitive to musty or earthy flavours, start with a Gayo or Lintong from a reputable roaster who sources carefully. Quality varies considerably in Sumatran coffee, and a poorly stored or processed bag can tip the earthiness into something murky and unpleasant. From a good roaster, sourcing from traceable farms, Sumatran coffee can be extraordinary.

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