Unknown Facts About Sumatra Coffee Beans The Story of Indonesian Mandheling Climate Formation Characteristics Processing Methods

For professional barista communication, please follow Coffee Workshop (WeChat official account: cafe_style)

Indonesian Coffee Origins

The main coffee-producing regions in Indonesia include Sumatra, Java, and Sulawesi islands, with "Mandheling" from Sumatra being the most famous.

Mandheling is also known as "Sumatra Coffee." Most coffee from northern Sumatra is Gayo, primarily of the Ateng variety. The Lake Tawar area in the northern part can be called Aceh coffee or Lake Tawar coffee, while the Lintong and Lake Toba areas in southern Sumatra can be called Mandheling. The Lintong area is truly the Mandheling production region. The best Mandheling varieties include four types: Sidikalang, Bergendar, Siborong borong, and Telok Sanggul.

Lake Toba

Lake Toba, located in central North Sumatra Province. In 1888, Dutch colonists moved "Java Mandheling" north to the Lake Toba region, creating the modern Mandheling legend.

Lake Tawar

Lake Tawar, located in central Aceh Special Autonomous Region. Situated at the northern tip of Sumatra Island, its area is less than one-tenth of Lake Toba. However, in recent years, coffee quality and production have surpassed Lake Toba.

The Gayo Mountains are located in the Aceh production region of northern Sumatra Province. Most coffee farmers working in Gayo are local farmers. The term "Gayo" originates from tribes in Indonesia's Aceh region. This area has ideal growing conditions, a long historical culture, and unique flavors. The region widely employs 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.

What is "Golden Mandheling"?

When discussing "Golden Mandheling," we must first talk about PWN. This abbreviation is often mixed with Mandheling coffee names - it's actually an abbreviation for Pwani Coffee Company.

This company is a very famous coffee acquisition company in Indonesia, mainly acquiring Mandheling coffee. Almost all of Indonesia's best production regions are acquired by them, so most beans from PWN company are unique specialty coffees. Golden Mandheling is a product produced by this company. After acquiring raw beans, they undergo multiple manual hand-sortings to select full, defect-free beans. Only these fine beans, which experience layer-by-layer screening like an audition process, can be classified as Golden Mandheling.

However, PWN company has registered Golden Mandheling as a trademark, meaning only Golden Mandheling produced by PWN company can be considered genuine "Golden Mandheling" in the future. Many beans on the market not produced by PWN company but bearing the Golden Mandheling brand name should actually be called Premium Mandheling.

"Golden Mandheling" is merely a product named by a company.

Processing Method

Wet Hulling, also known as Wet Hulling or Giling Basah in the local language, is the traditional Indonesian coffee processing method. Judging by name alone, Wet Hulling seems very similar to wet processing (washed processing), but the cupping flavors of these two processing methods are completely different. Coffee processed by Wet Hulling typically has a thick and intense flavor with a very distinct personality.

Wet Hulling Processing Steps

① Remove skin and pulp, keeping parchment and mucilage

② Water tank fermentation

③ Wash away mucilage

④ Sun-dry with parchment for 2-3 days until moisture content reaches 20-24%

⑤ Hull the parchment

⑥ Dry raw beans until moisture content reaches 12-13%

⑦ Prepare for export

Why Use Wet Hulling?

a. Climate reasons

The tradition of using Wet Hulling in Indonesia stems from local weather conditions. Indonesia maintains humidity between 70-90% year-round with continuous typhoons. In some regions, annual rainfall can even reach 2,000mm. Raw beans are most vulnerable to rain - how does Indonesia overcome such harsh weather conditions to produce rich, mellow Mandheling coffee? That relies on Wet Hulling.

Under tropical climate conditions, coffee takes an average of 2-3 weeks to dry. In Indonesia's extremely humid climate, drying coffee becomes a major problem. Coffee drying requires longer time, during which the coffee maintains high humidity, making it easier for bacteria to penetrate raw coffee beans.

In regular washed processing, drying occurs with parchment to protect raw beans from external damage. However, we notice that Wet Hulling removes parchment for the final drying step, allowing direct sunlight on raw bean surfaces, making coffee beans dry 2-3 times faster than washed processing.

b. Economic benefits

Dutch colonists first introduced coffee to Indonesia in the 17th century. These colonists pursued more and faster economic returns. Wet Hulling greatly reduces time spent on farms and significantly lowers labor costs. This aligns with the investor mentality of pursuing quick profits and reducing costs. This is also a driving force behind Wet Hulling.

c. Defects and kuku kambing (goat hoof beans)

When hulling parchment in Wet Hulling, coffee moisture content remains high at 20-24%, while in regular processing methods, coffee moisture content drops to 10-12% before hulling. In the "semi-dry" state, parchment tends to adhere to raw bean surfaces, making hulling more difficult than with "fully dry" beans, requiring greater friction during the hulling process.

However, on the other hand, "semi-dry" raw coffee beans are very fragile at this point, with hardness far below "fully dry" raw beans, so beans are more easily crushed, forming small gaps. This is what we commonly call horse hoof or goat hoof beans (locally called kuku kambing).

The ultra-fast processing speed of Wet Hulling also results in higher defect rates in Mandheling. Processing plants arrange employees for manual defect sorting, typically including DP (double picking) and TP (triple picking). Mandheling that undergoes triple picking will have better defect rates than double picking.

The flavor of Wet Hulling, apart from subtle differences, is generally believed to have earthy, smoky, and chocolate notes, with acidity described as "low acid" - thick yet seemingly dull.

Low acidity originates from shorter, weaker fermentation processes and longer drying times. As for the "earthy" flavors of Wet Hulling beans, opinions vary widely. Some say it's related to the bean varieties used in Wet Hulling-related regions (Timor & Catimor lines: with Robusta blood), some say it's the result of organic interactions between raw beans and the external environment, and some even say it's because there are too many defective beans! Of course, there are quite many...

FrontStreet Coffee Raw Bean Analysis

Gold Mandheling Raw Beans

Golden Mandheling

Origin: Sumatra Island, Indonesia

Processing Method: Wet Hulling

Variety: Typica

Roast Level: Medium-Dark

FrontStreet Coffee chooses to drop beans before the second crack to preserve some soft acidity. The taste has high sweetness, rich aroma, and mellow thickness. Flavors: toasted bread, pine, caramel, cocoa, with slight earthy notes.

In the specialty coffee system, Sumatra coffee is a fascinating existence. You see, the famous Mandheling is actually not a regional name, nor a coffee bean variety name, and even its bean variety origins are quite chaotic.

Ateng

A hybrid variety between Arabica and Robusta with several subtypes, widely planted in Sumatra and other Indonesian islands. Simply put, it's a branch of Catimor, with Ateng being the local name.

Djember

Djember, when searched on Baidu, is a place name in Sumatra. It seems mysterious, but the variety is actually S-795. Since this bean variety was spread to the island by Jember Coffee Research Center, locals call S-795 by this name.

What is S-795? It's a hybrid created by Indian botanists crossing the Typica mutant Kent with S-288.

What is S-288? It's a natural hybrid of Arabica and Liberica.

TimTim

It's Timor Hybrid, translated as East Timor Hybrid, which is a hybrid of Arabica and Robusta. Our familiar Catimor is created by hybridizing with it again.

Tim Tim — Longberry Mandheling

Tim Tim is a bean from Indonesia. Due to its elongated shape, many people call it horse face bean, while others call it long Mandheling. Actually, tim tim is not a pure variety but a natural hybrid between Arabica coffee trees and Robusta coffee trees. This variety was discovered on Timor Island in the 1940s and cultivated due to its natural disease resistance. In America, this variety is called Hybrido de Timor, abbreviated as Tim Tim, while in Indonesia, this variety is also called Bor Bor.

FrontStreet Coffee Roasting Analysis

Golden Mandheling belongs to raw beans with higher moisture content, with a relatively high deviation value in moisture compared to natural processed beans, so FrontStreet Coffee suggests paying special attention during dehydration. For raw beans with high moisture content, you can immediately close the air damper after adding beans, steam for 30 seconds, then open to level 3 until the bean color turns light green or white, then open the air damper to level 4, and open to level 5 (maximum) after the first crack.

FrontStreet Coffee suggests keeping detailed data records before roasting: coffee bean moisture content, density, origin, processing method, ambient temperature and humidity in the roasting room, etc., and planning your roasting curve. Record relevant chemical and physical changes during the roasting process - this will help you better understand the final roasting results and improve your roasting curve.

Roasting Curve:

Heat the roaster to 200°C and add beans, air damper at 3. After 1 minute, adjust heat to 160°C, air damper unchanged. Roast until 5'40", temperature 148°C, bean surface turns yellow, grassy smell completely disappears, dehydration complete. Adjust heat to 140°C, air damper to 4;

At 9'40 minutes, ugly wrinkles and black spots appear on bean surface, toast aroma clearly transforms to coffee aroma, can be defined as the prelude to first crack. At this time, listen carefully for the first crack sound. At 9'54" first crack begins, adjust heat to low (60°C), air damper fully open (adjust heat very carefully, not so low as to eliminate cracking sounds). Drop at 204.5°C.

FrontStreet Coffee Cupping Report:

Golden Mandheling tastes cleaner than Lintong Mandheling. The original herbal, earthy, and woody flavors of Mandheling are almost gone, but caramel sweetness is more intense, and fruit acidity is brighter and more elegant. Generally, Lintong Mandheling is best roasted past second crack to effectively reduce miscellaneous flavors, but Golden Mandheling dropped before or after second crack has good clarity and sweetness, offering wider roasting interpretation space.

FrontStreet Coffee Brewing Analysis

Medium-dark roasted beans generally have higher dehydration rates, so they weigh less. During brewing, the grounds don't completely sink to the bottom. When water is first poured, it's immediately absorbed. Due to vigorous degassing, bubbles surround the grounds, creating channels. These channels last longer with fresher beans, causing water levels to drop quickly. FrontStreet Coffee suggests using coarse water flow and slow circular pouring techniques for extraction.

1. Dripper: KONO

2. Water Temperature: 88°C

3. Grind Size: Fuji Royal grinder setting 4

4. Roast Level: Medium-dark roast

5. Bloom Time: 25 seconds

Flavor: Multi-layered, clean, balanced, with persistent caramel sweetness in aftertaste

FrontStreet Coffee specific technique: 15g coffee, Fuji Royal ghost tooth grinder setting 4, Kono dripper, 88-89°C water temperature. First pour 30g water for 25s bloom, then pour to 104g and stop. Wait until the bed level drops to half before pouring again. Slowly pour until reaching 220g, avoiding the last 5g. Water-to-coffee ratio 1:15, extraction time around 2:00.

Frontsteet Indonesia PWN Golden Mandheling Black Coffee Beans G1 Washed Imported Single Origin Specialty Fresh Deep Roast

Purchase link: https://item.taobao.com/item.htm?spm=a1z10.5-c-s.w4002-15673140460.18.14226b5fo2Tf9i&id=540335271875

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473