The Cultivation Story of Sumatra Coffee Beans? What are the Coffee Growing Regions in Sumatra? How to Brew Indonesian Coffee Beans?

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The Cultivation Story of Sumatra Coffee Beans

What are the coffee growing regions in Sumatra? How should you brew Indonesian coffee beans?

Sumatra Island extends from northwest to southeast, crossing the equator at its center, and consists of two regions: the Barisan Mountains in the west and swamplands in the east. Sumatra Island faces Java Island across the Sunda Strait to the southeast, is opposite the Malay Peninsula across the Strait of Malacca to the north, adjoins Borneo across the Karimata Strait to the east, and borders the Indian Ocean to the west.

Indonesian Coffee Production Regions

The main coffee bean producing areas in Indonesia are on three islands: Java, Sumatra, and Sulawesi, all of which have volcanic terrain. Indonesian coffee beans are generally considered to have rich aromas with low acidity, slightly reminiscent of herbal medicine and earthy flavors. The Mandheling coffee produced in the mountainous regions of Sumatra is world-renowned for its rich texture. The Robusta beans produced on Java Island have a unique aroma and are often used in espresso blends due to their rich oil content. Sulawesi coffee is rated as having special herbal notes—deep and clean. Interestingly, there is a special animal in the mountains of Indonesia called the civet cat (which has also appeared in Taiwan, where it is listed as one of the representative animals of Yangmingshan). Because of this animal, Indonesia produces one of the world's most expensive coffees—civet coffee. These cats like to eat coffee berries, and the hard coffee beans, being indigestible, are eventually excreted. During their passage through the digestive tract, the coffee beans undergo fermentation, producing a unique and complex aroma that many connoisseurs appreciate. However, due to extremely limited production, the price is extraordinarily high, reaching hundreds of dollars per pound.

Sumatra's Unique Coffee Processing

Sumatra Island is Indonesia's largest island, located on the equator and featuring a tropical rainforest climate with high temperatures, humidity, and abundant rainfall. Coffee smallholders typically grow their coffee in pristine mountainous areas where water resources are precious. Consequently, the region has developed a unique "wet hulling" segmented drying processing method (Giling Basah), which adds flavors to Sumatran coffee that differ from other regions. Among Indonesia's coffee beans, 25% are Arabica, while the remaining 75% are Robusta. Only the refined Arabica coffee from northern Sumatra is marketed under the names Lintong and Mandheling.

Sumatra Coffee Characteristics

The coffee grown in Sumatra's environmental soil is rich in woody tones and mellow口感 (mouthfeel), with restrained flavors and lively yet moderate acidity. It also features unique flavors such as herbal medicinal notes, cedar, cocoa, and fermented fruits. Among these, Mandheling represents the most classic coffee variety among the 25% Arabica coffee species produced in Indonesia. It has a wonderful classic flavor—rich taste with body and vibrant, lively dynamics, yet neither astringent nor acidic, allowing the body and bitterness to be fully expressed. When tasting Mandheling, one can experience a smooth sensation on the tongue, accompanied by faint herbal plant aromas, cocoa sweetness, and fruit-like fragrances, with a long-lasting aftertaste. Mandheling enthusiasts typically drink it as a single-origin coffee, but Mandheling is also an indispensable variety for blending coffee.

Historical Background

In the 17th century, the Dutch first introduced Arabica seedlings to Java Island, gradually expanding to Sumatra and other Indonesian islands. In 1877, a massive rust disease attacked the Indonesian islands, nearly wiping out the Arabica trees planted at low elevations. Many farmers had to abandon their long-cultivated Arabica coffee trees and introduce Robusta coffee trees from Africa, which have stronger disease resistance. Only a few high-altitude areas continued to grow Arabica varieties, and these surviving Arabica trees are the ancestors of today's world-famous Mandheling and Lintong coffees, known for their unique flavors.

Terroir and Growing Conditions

Volcanic Ash Soil: The Barisan Mountains are a continuation of the Qinghai-Tibet Plateau's Cenozoic mountain range, running through Sumatra Island. Coal and gold deposits have been discovered in this region. Minerals erupted by volcanoes make the soil fertile. The mountain scenery is beautiful and captivating, such as the area around Lake Toba.

Growing Altitude: Sumatran Mandheling is typically grown at high altitudes between 1,200-1,500 meters. Abundant rainfall and volcanic soil conducive to coffee cultivation produce premium Mandheling coffee beans.

Premium Mandheling Characteristics

The selected Mandheling from the mountainous areas around Lake Tawa in Indonesia's Aceh Special Region and the Lake Toba area in Indonesia's North Sumatra Province features relatively large coffee beans with harder texture. Defects can easily occur during cultivation, but through three rounds of strict manual defect removal, the flavor becomes cleaner and more transparent without off-flavors. The flavor profile is clean, with gentle fruit acidity and a slightly muted aroma, featuring a thick, viscous mouthfeel with charming cream aroma and some bitter notes, with a full aftertaste.

Flavor Description: With distinct cream and chocolate aromas, along with some brown sugar and caramel flavors, the taste is rich and mellow, with a long-lasting aftertaste. The dry aroma has obvious smoky wood and herbal aromas, walnut-like rich oily nut fragrances, and dark chocolate aroma. It tastes mellow and full, warm and dense, with excellent sweet aftertaste and a long dark chocolate finish.

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. First pour 25g of water for a 30-second bloom, then continue pouring to 238g total water, with an extraction time of about 2:30 minutes.

Analysis: The KONO dripper doesn't have many ribs at the bottom, allowing the filter paper to fit closely against the dripper, which restricts airflow. This allows water and coffee grounds to have longer contact and soaking time in the dripper, ensuring extraction time and rate for coarse grinding. This enables the coffee grounds to be fully extracted, enhancing the mellow mouthfeel and making the flavor more concentrated.

Flavor: High balance, clean taste with heavy, solid mouthfeel, and persistent dark chocolate aftertaste.

Important Notice :

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