Sumatra is the core coffee-producing region of Indonesia, where the exceptional volcanic soil and tropical rainforest climate give rise to richly flavored coffee. From the introduction of Typica during the Dutch colonial period, to the shift to disease-resistant varieties after leaf rust, and then to the rise of Mandheling, this land has written a unique coffee legend. The two major lake regions, Lake Toba and Lake Tawar, each have their own characteristics, while the wet-hulling process gives Mandheling its signature woody and spicy notes. This article will guide you through the origin story and processing methods of Sumatran coffee, and provide an in-depth analysis of Front Street Coffee PWN Golden Mandheling's cupping performance and pour-over key points, showcasing its unique charm of full body, low acidity, and long-lasting finish.
Sumatran coffee comes from the island of Sumatra in Indonesia, Asia, and people usually refer to it directly by the island's name. This coffee has a very intense taste, prominent aroma, obvious bitterness, a thick mouthfeel, and a slight sweetness in the finish. Many coffee enthusiasts enjoy it as a single-origin brew, and it is also an indispensable component in coffee blends. In an era before Blue Mountain coffee was widely known, Sumatran coffee was once recognized as one of the finest coffees in the world. After roasting, the beans are quite large, with raw beans appearing brown or dark green, emitting a unique aroma reminiscent of caramel. It tastes rich and mellow, with prominent bitterness and almost no gentle acidity. Due to limited total production, its price is usually higher than ordinary coffee beans.
The Origins of Sumatran Coffee
Sumatra is the largest island in Indonesia, with the Indian Ocean to the west and the South China Sea to the east, and the equator passes right through the center of the island. Moreover, it lies on the Pacific Ring of Fire, with volcanoes scattered across the island, endowing the land with nutrient-rich volcanic ash soil. The mountainous areas are shrouded in mist and clouds year-round, with high elevations, abundant rainfall, and ideal temperatures, making the island extremely rich in natural products, with coffee being one of the most suitable crops to cultivate.
The story of Indonesian coffee begins in the late 17th century. At that time, the Dutch occupied Java and established it as the oriental stronghold of the Dutch East India Company, introducing two batches of Typica seedlings from India to Java for trial planting. By the 1870s, coffee-growing areas had been established in Sumatra, Bali, Sulawesi, and Timor, quickly spreading from Java to the rest of Indonesia. Unfortunately, this good fortune did not last long. In 1869, coffee leaf rust suddenly broke out, sweeping through coffee-producing regions across Asia including Indonesia, and large numbers of local Typica trees withered and died from the disease.
To save the devastated coffee plantations, the Indonesian government introduced more disease-resistant Robusta varieties from Africa and elsewhere, and to this day Robusta remains Indonesia's primary variety. To ensure plant survival and increase yields, Indonesia continuously introduced various disease-resistant varieties from other countries. Among them, the Robusta-Arabica hybrids Tim Tim, Bor Bor, and the Catimor series Ateng, due to their good disease resistance, high yields, and adaptability to Sumatra's terroir, quickly replaced the original Typica and became the main varieties in Sumatra and other areas. The famous specialty representative among them is Mandheling.
Introduction to Mandheling Coffee Producing Regions
Mandheling is mainly produced in two major lake regions within Aceh Province and North Sumatra Province: Lake Toba and Lake Tawar.
Lake Toba is the largest volcanic lake in the world and also the largest highland freshwater lake in Indonesia. The average annual temperature here is about 22°C, with a tropical rainforest climate, rainy and humid, plus a mountainous elevation of about 1,400 meters, making it abundant in various spices, timber, palm oil, and other agricultural products, with coffee naturally among them. Under the continuous rainy weather, most fruit trees grow on higher-elevation slopes, and various ferns cover the ground, together providing good sun protection for coffee, so growers do not need additional shade.
Located in the central part of Aceh Province, Sumatra, the Gayo Highlands possess a very unique microclimate, close to the famous volcanic Lake Tawar. Here the lake water is clear, the natural environment is superior, and coffee trees are planted at elevations of 1,200–1,800 meters on high mountains, shrouded in mist year-round, with large temperature differences between day and night. The volcanic soil is rich in minerals and nutrients, and fallen fruit naturally decomposes into fertilizer. Farmers widely adopt organic farming methods for coffee, and combined with a long history of cultivation, the coffee produced here is higher in both quality and yield. Many green coffee bean traders also value this area more, including the locally famous Pwani Coffee Company (PWN).
From September to April of the following year is the coffee cherry ripening season, and you can see many farmers busy picking in the mountains. Traditional Lintong Mandheling is grown by the Mandailing and Batak peoples, while the "rising star" Lake Tawar Mandheling is grown by the Gayo people.
Have You Heard of the Wet-Hulling Process?
The biggest difference from many coffee-producing regions is that Indonesia mostly has humid weather, with year-round humidity between 70–90%, typhoons that can come at any time, and annual rainfall reaching over 2,000mm. Such harsh weather makes it impossible to use the 2–3 week sun-drying method like in Africa. Washed processing is not only time-consuming but also requires more labor and water resources, which Indonesia, with its focus on mass production, simply cannot afford. Thus, a unique semi-washed method was developed — the wet-hulling process.
Coffee cherries with the skin and pulp removed are poured directly into pools for a short fermentation of a few hours. At this point, a small amount of mucilage still remains on the parchment. The mucilage is removed by scrubbing. Then the parchment beans are spread out to dry. The first drying only needs to reach 30–40% moisture content, about 2–3 days, after which the coffee farmers sell the raw beans to collectors. The collectors will directly hull the purchased semi-dry parchment beans by machine to obtain the innermost green beans.
Because the hulling machine uses greater friction to tear open the parchment layer tightly attached to the green beans, at this stage, white or green viscous liquid often flows out. Due to prolonged soaking in mucilage and the humid environment, the green beans eventually become soft, whitish and swollen, forming a gray-green color. Through the friction and agitation, the green beans are also more easily crushed or bruised, especially at both ends, forming small notches that create "goat-foot" beans. The "naked beans" with the parchment removed dry very quickly, while also being directly exposed to the humid environment, subject to the growth of various microorganisms. This gives the coffee its unique woody, spicy, and herbal notes — what we call the "Mandheling flavor."
The Finest Among Mandheling — Front Street Coffee PWN Golden Mandheling Coffee Beans
As a representative of Sumatran coffee, Mandheling was originally a very small place name, which later gradually evolved into the name of an ethnic group — Mandailing. Mandheling coffee rose to fame after Pwani Coffee Company (PWN) successfully marketed Mandheling for sale in Japan. Pawani is a trading company engaged in export business, founded by a Chinese family from Quanzhou, Fujian, located in Medan, an important port in Sumatra. It has been in the export business since 1957, dealing in products such as rubber, cassia seed, cloves, and patchouli oil, and of course including exporting Sumatran coffee beans to Japan.
Unlike many local green bean traders in Indonesia, PWN is the exclusive supplier of high-grade Golden Mandheling coffee, having contracted the best Mandheling coffee-producing regions in Indonesia, and the Mandheling beans it produces are all of premium quality. The Golden Mandheling coffee that has long held the top-right position on Front Street Coffee's bean list comes from PWN, and the Dongshankou store even displays the burlap sacks used for packaging green beans and certification certificates.
The wet-hulling process saves a great deal of time and labor costs in green bean processing; however, the rapid process also brings a higher defect rate, so only strict hand-sorting can remove defects that machines cannot screen out. PWN subjects the purchased Mandheling green beans to one machine sorting plus three rounds of hand sorting, with quality far exceeding Indonesia's highest G1 grade. To meet Front Street Coffee PWN Golden Mandheling production standards, the following requirements must be met:
1. Green bean screen size: 18–19 mesh or above after first hand sorting
2. Fewer than 3 defective beans in a 300-gram green bean sample
3. Green coffee bean grade is G1
4. Color tends toward dark green, uniform in size, neat in shape
Before launching any coffee bean, Front Street Coffee tastes the coffee through cupping. Cupping is an evaluation of coffee bean quality and flavor; a unified standard allows for a more objective identification of the strengths and weaknesses of the flavors the beans present, as well as their characteristics. After cupping, Front Street Coffee found that the Lintong Mandheling everyday drinking beans present a rich nutty profile, with a hint of melon aroma in the finish. After the temperature drops, herbal notes emerge, with a full body and saturated aroma. Front Street Coffee PWN Golden Mandheling not only has the aroma of dark chocolate, nuts, and caramel, but also the flavors of herbal spices and pine wood, with the sweet finish of dark chocolate, a full aftertaste, high cleanliness, and a gentle fruit acidity after the temperature drops.
The Best Pour-Over Method for Golden Mandheling
Golden Mandheling coffee has a complex aroma. To experience the best flavor and mouthfeel, Front Street Coffee recommends using freshly roasted coffee beans for brewing. Coffee beans reach their optimal tasting period 4–7 days after roasting. After this period (about a month and a half), the aroma will gradually fade and produce woody defect flavors. Front Street Coffee believes that the freshness of coffee beans is especially important, so the coffee beans shipped are freshly roasted within 5 days. Combined with logistics and shipping time, they are ready to enjoy upon receipt.
Front Street Coffee's brewing approach for each coffee bean is based on the characteristics the coffee presents during cupping. For example, Golden Mandheling coffee has flavors of herbs, dark chocolate, caramel, nuts, and pine wood. For this type of full-bodied bean, Front Street Coffee's baristas use the Kono dripper. Kono's ribs do not reach halfway up the dripper's height. This design is actually to ensure that the filter paper clings tightly to the dripper wall after wetting, restricting airflow. This increases the water absorption time of the coffee grounds, resulting in a more evenly extracted coffee overall and enhancing the full-bodied mouthfeel. The groove framework at the bottom of the Kono dripper is also a key design that allows the subsequent brewing to produce a siphon effect.
Because deeply roasted coffee beans are relatively loose and highly absorbent, they can easily absorb too much water and become over-extracted, resulting in Mandheling coffee that is both bitter and astringent. Therefore, Front Street Coffee will adjust the grind size coarser and use slightly lower-temperature water for brewing.
Suggested brewing parameters: Water temperature: 87–88°C Coffee grounds: 15g Coffee-to-water ratio: 1:15 Grind size: medium grind (70% passing through China standard No. 20 sieve)
The brewing method uses a three-stage pouring technique. Dividing into three stages better expresses Golden Mandheling coffee's full-bodied mouthfeel and caramel sweetness. The first stage is the bloom, pouring 30ml to fully wet the coffee grounds for degassing, in order to better extract the coffee's flavor compounds in the subsequent steps. The second stage pours 100ml, mainly to wash out all of Mandheling's golden foam and raise the coffee bed. The final stage is a gentle center pour of 95ml. After all the coffee liquid has drained through, remove the dripper and gently swirl the carafe to even out the coffee.
The pour-over Front Street Coffee PWN Golden Mandheling coffee tastes very rich, exuding spicy and herbal notes, with an overall solid, full-bodied mouthfeel, caramel sweetness, and flavors of chocolate and nuts.
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The above content is compiled by CoffeeHunters, a coffee news website.
