Introduction to Indonesian Mandheling Coffee Beans from Sumatra's Lintong Region

Indonesian Mandheling coffee is the representative coffee of Asian Indonesia. Mandheling is not the name of a coffee-producing region, but rather the homophone of the Mandheling tribal people in northwestern Sumatra, Indonesia. During World War II when Japan occupied Indonesia, a Japanese soldier drank an incredibly mellow coffee at a café. When he asked the owner the name of the coffee, the owner misunderstood and thought he was asking "Where are you from?" and replied: "Mandailing." After the war, the Japanese soldier recalled the coffee he drank in Indonesia was called "Mandheling," and later people began referring to the Arabica beans produced in Sumatra as Mandheling coffee.

Mandheling coffee is produced on Sumatra Island in Indonesia. Indonesia is a Southeast Asian country and the world's largest archipelagic nation, with Jakarta as its capital. It borders countries such as Papua New Guinea, East Timor, and Malaysia. Indonesia was one of the earliest places to grow coffee, besides Yemen.

At the end of the 17th century, the Dutch first introduced Arabica seedlings to Ceylon (today's Sri Lanka) and Indonesia. The Dutch first transplanted Arabica Typica to Jakarta on Java Island. Due to suitable local climate and soil conditions, Arabica quickly spread to Sumatra in northwest Java and another large island, Sulawesi, in the northeast. In 1877, a large-scale disaster struck the Indonesian islands. Coffee rust disease destroyed almost all coffee trees, forcing people to abandon the Arabica they had cultivated for years and introduce Robusta coffee trees from Africa, which had stronger disease resistance.

Today, Indonesia has become a major coffee-producing country, with coffee production mainly concentrated in Java, Sumatra, and Sulawesi. Robusta varieties account for 90% of total production. Sumatran Mandheling, however, is the rare Arabica variety. Currently, Mandheling coffee generally refers to Arabica coffee beans from Sumatra Island, Indonesia.

Indonesian Coffee Bean Growing Environment

Indonesia has a typical tropical rainforest climate with average annual temperatures of 25-27°C, no distinct seasons, and annual precipitation of 1600-2200mm. Indonesia is located in a volcanic zone with fertile, mineral-rich soil that is favorable for coffee bean cultivation and growth. Indonesia's elevation ranges between 900-2100 meters, with main coffee-growing areas concentrated around 1200 meters.

Indonesian coffee beans have two main harvest seasons. The main harvest season is approximately from September to October, while the secondary harvest season is from May to June. This year, Indonesia's coffee bean exports have increased significantly compared to last year. Analysis suggests this is due to reduced exports last year caused by high Indonesian coffee prices, coupled with increased production during the current season, leading to substantial growth in Indonesian coffee exports.

Indonesia's main coffee-producing regions include Sumatra Island, Java Island, and Sulawesi Island, with "Mandheling" from Sumatra Island being the most famous. In the northern Lake Tawar region, it can be called Aceh coffee or Lake Tawar coffee. The Lintong and Lake Toba areas can be called Mandheling. There are eight provinces in total, but only two provinces grow coffee extensively—Aceh Province and North Sumatra Province. The most representative coffee-producing areas in these two provinces are the Gayo mountains surrounding Lake Tawar in Aceh Province, where coffee is grown by local indigenous Gayo people. Coffee in North Sumatra Province is grown around Lake Toba. This lake is extremely large and is the world's largest volcanic lake. Mandheling produced from Lake Tawar and Lake Toba is the famous "Two Lakes, Two Mandhelings," while south of Lake Toba lies the Lintong producing region.

Lake Toba

Lake Toba is located north of Medan, the capital of Sumatra Island, and is a high-altitude freshwater lake with an average elevation of approximately 900m. The lake has a diamond shape, 100 kilometers long and 30 kilometers wide, covering an area of 1,130 square kilometers. It is a high-altitude lake with an average elevation of around 1100-1600 meters and is also the world's largest volcanic lake. The commonly referred to Mandheling typically refers to Typica or its variety coffee beans grown in the mountainous areas surrounding Lake Toba. Among these, Lintong is the most famous Mandheling coffee-producing region in the Lake Toba area. FrontStreet Coffee's stores feature a FrontStreet Coffee Lintong Mandheling.

FrontStreet Coffee's Lintong Mandheling, with unsorted green beans, sometimes shows inconsistent quality, but largely retains the flavor characteristics of Sumatran coffee—strong, rich taste with unique spicy and herbal aromas. Therefore, FrontStreet Coffee also lists FrontStreet Coffee Lintong Mandheling as part of FrontStreet Coffee's high-value daily coffee bean series, allowing everyone to experience the unique taste of Indonesian coffee.

Aceh Gayo Mountain Region

The Gayo Mountain (Gayo) region is located in Aceh Province in northern Sumatra Island. Coffee in the Gayo Mountain (Gayo) region is grown on hillside slopes surrounding the town of Takegon and Lake Tawar. The growing elevation in production areas averages between 1,110 and 1,600 meters. Coffee is grown by small farmers under shade trees and processed using the wet-hulled method to express unique flavors with deep and lively rich body. Aceh, at the northernmost tip of Sumatra Island, is a fascinating and complex place.

Due to long-term political instability, Aceh is not a region that ordinary people typically visit. The Gayo Mountains are located in the Aceh producing region of northern Sumatra Province. Most coffee farmers working in Gayo are local farmers. The term "Gayo" originates from the tribal people in the Aceh region of Indonesia. This region has ideal growing conditions, a long historical culture, and unique flavors. The region widely adopts organic methods for coffee cultivation, without using chemical fertilizers, and is considered a world green coffee production area. Therefore, Gayo coffee is often called green coffee or Gayo organic coffee.

Lake Toba, located in central North Sumatra Province. In 1888, Dutch colonists moved "Java Mandheling" north to the Lake Toba area. Lintong in South Sumatra and the Lake Toba area can be called Mandheling. The Lintong area is truly the Mandheling producing region. Mandheling is produced from the mountainous areas surrounding Lake Toba. This lake is located north of Medan, the capital of Sumatra Island, and belongs to high-altitude freshwater lakes with an average elevation of approximately 900 meters. The commonly referred to Mandheling typically refers to Typica or its variety coffee beans grown in the mountainous areas surrounding Lake Toba.

Lake Tawar, located in central Aceh Special Administrative Region. Situated at the northern tip of Sumatra Island, most coffee produced in North Sumatra is Gayo, primarily of the Ateng variety. The Lake Tawar at the northern end can be called Aceh coffee or Lake Tawar coffee. Its area is less than one-tenth of Lake Toba. However, in recent years, coffee quality and production have surpassed Lake Toba.

Because Indonesia has thousands of islands, not all coffee from the country tastes the same. Besides Java Island, coffee beans from Indonesia's Sumatra Island are renowned worldwide for their heavy body, low acidity, and earthy, spicy, herbal aromas, making Mandheling coffee beans globally celebrated.

Indonesia's Unique Coffee Processing Method—Wet Hulling

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 the name alone, wet hulling seems 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 character.

The uniqueness of FrontStreet Coffee's Mandheling coffee flavor comes from the local unique post-processing method for green coffee beans. Due to year-round rainfall and high air humidity in Sumatra, if the dry processing method were used, coffee cherries might become ruined due to rain exposure or even over-fermentation, so this cannot meet the conditions for dry processing.

Additionally, washed processing requires sufficient water sources and adequate funding, but local economic conditions are limited and cannot fully meet washed processing requirements. Therefore, the highly Sumatra-characteristic wet hulling processing method emerged, requiring short drying times and using less water during the process.

Wet processing: After removing the skin and pulp of coffee cherries, the parchment beans with sticky mucilage are briefly washed and then placed in water tanks for short-term fermentation. The longer the fermentation time, the heavier the acidity. Some processing plants or estates even skip the fermentation step entirely, directly spreading the parchment beans evenly for drying. This both inhibits acidity and increases the viscosity of the mouthfeel. The parchment layer serves to some extent as a protective layer for green coffee beans, protecting them from external damage.

However, the local climate in Sumatra is too humid, and coffee drying requires longer time periods. During this short time, maintaining coffee at high humidity can lead to bacterial infection, causing coffee beans to be ruined. Removing the parchment layer allows sunlight to directly hit the surface of green coffee beans, enabling them to dry quickly.

During the process of removing the parchment layer, significant friction is generated between green coffee beans and between beans and machinery. The excessive heat generated may cause coffee to age rapidly, resulting in the woody and earthy special flavors found in Sumatran coffee.

This special wet processing method causes FrontStreet Coffee's Mandheling coffee beans to show cracking and asymmetrical shapes, what we call "goat hooves." This is not considered defective beans—it's normal. Some friends even say that the uglier Mandheling coffee beans are, the better their flavor.

Gold Mandheling Coffee

Another frequently mentioned FrontStreet Coffee Mandheling coffee bean is called "Gold Mandheling," where the word "Gold" reflects the high quality of these coffee beans. FrontStreet Coffee sources Gold Mandheling from PWN company. PWN company uses extremely strict standards when producing FrontStreet Coffee Gold Mandheling—green coffee beans are sized 18 screen or above, and in every 300-gram green bean sample, the number of defects is fewer than 3. On top of meeting G1 grade standards, they add three rounds of manual hand-sorting to ensure complete removal of defective beans, thereby maximizing flavor cleanliness and enhancing sweetness.

Traditional Mandheling coffee flavor has a rich body due to darker roasting levels. To present traditional Mandheling flavor, FrontStreet Coffee uses medium-dark roasting when roasting Mandheling.

FrontStreet Coffee's Mandheling Brewing Parameters:

The special feature of the Kono dripper is that its "ribs" channels extend to the bottom of the coffee liquid outlet hole. Because the ribs are at the bottom and short, they fit closely with filter paper, so the flow rate is slower than V60, thereby increasing coffee extraction rate and enhancing coffee body.

Dripper: KONO dripper, Water temperature: 88°C, Coffee dose: 15 grams, Coffee-to-water ratio: 1:15, Grind size: Medium-coarse grind (China standard 20-mesh screen 75% pass rate).

Using segmented extraction, bloom with 2 times the coffee dose in water, i.e., 30g water blooming for 30 seconds. The blooming process is needed to allow coffee powder to release internal carbon dioxide gas, making later extraction more stable. Use small water flow in circular motions to 125g for segmentation, continue pouring water to 225g then stop. After the water in the dripper finishes dripping, remove the dripper. Start timing from the beginning of pouring, extraction time is 2'00". Next, pick up the entire cup of coffee and shake it evenly, then pour into cups for tasting.

[FrontStreet Coffee Lintong Mandheling Coffee Flavor Characteristics] Herbal, chocolate, caramel, overall relatively balanced.

[FrontStreet Coffee Gold Mandheling Coffee Flavor Characteristics] Nuts, spices, herbal plants, licorice, chocolate, caramel.

FrontStreet Coffee Brewing Suggestions:

Regarding coffee brewing, FrontStreet Coffee has always believed that the freshness of coffee beans greatly affects coffee flavor. Therefore, FrontStreet Coffee (FrontStreet Coffee) ships coffee beans roasted within 5 days. FrontStreet Coffee's roasting philosophy is "freshly roasted good coffee," ensuring every customer who places an order receives the freshest coffee when it arrives. The coffee resting period is about 4-7 days, so when customers receive their coffee, it's at peak flavor.

For friends who need ground coffee, FrontStreet Coffee kindly reminds: once coffee beans are ground in advance, there's no need for resting, because during transportation, the pressure from carbon dioxide in the packaging also helps coffee flavor become rounded, so you can brew a cup immediately upon receiving ground coffee. However, ground coffee needs to be brewed promptly, because coffee powder oxidizes quickly after contact with air, meaning coffee flavor dissipates relatively quickly, and the coffee won't taste as good. Therefore, FrontStreet Coffee suggests buying whole beans and grinding fresh before brewing to better taste the coffee's flavor.

Indonesian Mandheling's flavor is one of the world's richest coffees. If you're not accustomed to this herbal pine rich flavor, you can try Ethiopia's light and fresh floral and fruit aromas! FrontStreet Coffee's stores also sell Ethiopian washed Yirgacheffe coffee, which is a popular daily coffee bean!

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