Sumatran coffee is known for its distinctive flavour profile that tends to evoke strong reactions—people either love it or dislike it. Characterised by low acidity, a thick body, and earthy, rustic notes, Sumatran coffees can be quite polarising. The unique flavours arise largely from the processing method known as wet-hulling, or Giling Basah in Bahasa, which sets these coffees apart from the more commonly wet-processed varieties.
The Polarising Nature of Sumatran Coffee
The taste of typical wet-hull Sumatra can be a contentious topic among coffee enthusiasts. While some coffee drinkers revel in the earthy, "foresty" notes—often reminiscent of herbs, moss, or mushrooms—others would consider these same characteristics defects if found in coffees from other regions. When placed alongside well-processed Central American coffees, a Sumatran would likely be dismissed for its unconventional taste.
Yet, for those who appreciate complexity in their cup, the flavours of Sumatran coffee can be a welcome diversion from the more traditional profiles found in coffees from Central America, Colombia, or Kenya. Many who enjoy minimally processed wines with earthy tones may find something to love in the Sumatran experience.
The Wet-Hulling Process
Most Indonesian coffees, including those from Sumatra, undergo the wet-hull processing method. In this approach, small-holder farmers harvest coffee cherries and pulp them using a hand-crank machine. The cherries are then fermented in various containers to break down the mucilage, following which the wet parchment coffee is produced.
Unlike traditional wet-processing, where beans are dried slowly for optimal flavour, the wet-hulling method prioritises speed and cash flow for farmers. This often results in coffee being sold with a higher moisture content, and the beans are hulled while still swollen with water. The lack of protective layers during drying can lead to a lower-acid cup with enhanced body, but it also risks damage to the beans, leading to potential quality issues.
Quality Control and Distinction
While the wet-hulling method can create challenges, it doesn’t mean all wet-hulled coffee is of poor quality. There are mills dedicated to high standards of cleanliness and careful processing, consistently producing exceptional lots. When tasting Sumatran coffee, we look for sweetness—perhaps in the form of muscovado or molasses—as well as rustic elements that suggest positive earthiness without veering into unpleasant flavours.
The History and Varieties of Sumatran Coffee
Sumatra began cultivating coffee after the crop was introduced to Java in Indonesia during the 18th century, with initial production centred around the northern region of Aceh. Today, Sumatran coffee is often sold under the name Mandheling, named after the Indonesian ethnic group that historically produced it. The grading of Sumatran coffees is based on cupping scores rather than the appearance of the green beans, which can be somewhat misleading in terms of actual cup quality.
The coffee grown in Sumatra comprises a mix of cultivars, including the original Typica, various hybrids, and Arabica beans with Robusta inputs. However, the prevailing influence on flavour remains the wet-hulling process, which can overshadow the importance of specific varietals.
Challenges Facing Sumatran Coffee Cultivation
Sumatra's coffee industry is not without its challenges. Pests like the Coffee Berry Borer (CBB) pose significant threats, infesting ripe cherries and complicating quality control. The small size of many farms means that timely picking of mature cherries is crucial to prevent infestation. However, unpredictable weather patterns can lead to irregular ripening cycles, making it difficult to manage.
Sumatran coffee is a fascinating blend of complexity and controversy, rooted deeply in its unique processing methods and rich history.