What separates G1 and G2 in Indonesian arabica coffee bean grading?

Indonesian arabica coffee bean grading sorts green beans mainly by defect count, with G1 allowing far fewer defects than G2. The same origin also produces Kopi Luwak, among the highest-priced coffees sold, while Mandheling remains the variety that well represents the country, showing moderate acidity, rich aroma, high body, and a full, solid texture.

Indonesia's coffee planting area ranks first globally, though lower efficiency puts total output third, behind Brazil and Vietnam. Dutch colonists introduced arabica coffee in 1699, planting it around Batavia, then spreading it to Java, Sumatra, Sulawesi, and Timor; North Sumatra's highlands saw plantings near Lake Toba in 1888 and the Gayo Highlands in 1924.

Indonesia is a major coffee-producing country globally, and both Mandheling and Kopi Luwak originate from here. This article systematically reviews the grading system for Indonesian Arabica coffee beans, focusing on the criteria for G1 and G2, while also revisiting Indonesia's coffee cultivation history, the distribution of major producing regions, and the unique wet-hulling process for Mandheling. The article also introduces the flavor profiles and brewing suggestions for two Indonesian beans from Front Street Coffee, providing coffee enthusiasts with a complete understanding from green bean grading to flavors in the cup.

Indonesia produces one of the world's most expensive coffees—Kopi Luwak—but the coffee variety that best represents this country is undoubtedly Mandheling. Mandheling has moderate acidity, an extremely rich aroma, a somewhat bitter taste, high body, and a full, solid texture, combining aroma, richness, body, and bitterness in one. Of course, if you are not fond of this style, drinking Mandheling can be as unpleasant as drinking Chinese herbal medicine.

Indonesian Coffee History

Indonesia is a major coffee-producing country in Asia and ranks among the top in global coffee production. Indonesia's coffee planting area ranks first in the world, but production efficiency is relatively low, so its total output ranks third globally, after Brazil and Vietnam.

In 1699, when Indonesia was still under Dutch colonial rule, the Dutch East India Company (VOC) introduced Arabica coffee plants with the aim of breaking the Arab world's global monopoly on the coffee trade. The Dutch colonial government initially planted coffee around Batavia (present-day Jakarta).

Subsequently, coffee plantations were established in East Java, Central Java, West Java, and parts of Sumatra and Sulawesi. Indonesia was the first place outside Arabia and Ethiopia to cultivate coffee on a large scale. Between 1725 and 1780, the VOC monopolized the coffee trade.

By the mid-17th century, the VOC expanded Arabica coffee cultivation to Sumatra, Bali, Sulawesi, and Timor. On Sulawesi, coffee was first planted in 1750. In the highlands of North Sumatra, coffee was first planted near Lake Toba in 1888, and later in 1924 cultivation also began in the Gayo Highlands (Aceh) near Lake Laut Tawar. In the late 18th century, Dutch colonists opened large coffee plantations on the Ijen Plateau in eastern Java.

In the 1920s, smallholder farmers across Indonesia began cultivating coffee as a cash crop. However, disaster struck in 1876 when coffee leaf rust swept through Indonesia, destroying most Typica varieties. In 1900, Robusta coffee (C. canephora var. robusta) was introduced to East Java as a replacement, especially in low-altitude areas where rust was particularly severe.

Plantations on Java were nationalized upon independence and were revitalized in the 1950s through the planting of new Arabica varieties. These varieties were also adopted by smallholders through government and various development programs. Today, more than 90% of Indonesia's coffee is grown by smallholders, with average farm size not exceeding one hectare.

Mandheling Coffee Growing Environment and Varieties

Indonesia is the world's largest archipelagic country, known as the "Country of a Thousand Islands." The islands are scattered, with mostly rugged mountains and hills within them, only narrow plains along the coast, and surrounded by shallow seas and coral. Indonesia has a typical tropical rainforest climate, with an average annual temperature of 25-27°C and no distinction between the four seasons. The northern part is influenced by the Northern Hemisphere monsoon, with abundant rainfall from July to September; the southern part is influenced by the Southern Hemisphere monsoon, with abundant rainfall in December, January, and February. Annual precipitation is 1600-2200 mm. Indonesia's high altitude, volcanic ash soil, and climatic characteristics all provide superior conditions for the growth of Arabica coffee trees.

At the end of the 17th century, the Dutch East India Company transplanted Arabica coffee trees from India to Jakarta on the island of Java. Due to the highly suitable climate and soil, Arabica quickly spread to Sumatra and the northeastern island of Sulawesi. However, in 1880 a severe leaf rust outbreak occurred in Java, and Arabica nearly died out. The Dutch switched to planting disease-resistant Robusta coffee, stabilizing Indonesia's coffee industry. To this day, Robusta remains the mainstay of Indonesian coffee, accounting for about 85% of national production, distributed in low-altitude areas such as Java and Bali. Arabica accounts for 15% of production, distributed in the high-altitude areas of northern Sumatra, Sulawesi, and Java.

The variety of Front Street's Lintong Mandheling coffee is TimTim Ateng, and the variety of Golden Mandheling coffee is labeled as Ateng. In fact, TimTim is Timor, an Arabica variety with Robusta lineage; and Ateng is Catimor, a cross between Caturra and Catimor. These variety names are simply local designations.

Indonesian Coffee Producing Regions

Sumatra

Sumatra is a large island in western Indonesia, straddling the equator, with an area of 473,000 square kilometers, making it the sixth-largest island in the world. To the northeast, it faces the Malay Peninsula across the Strait of Malacca, and to the west lies the Indian Ocean. The equator divides it in two, giving it a tropical rainforest climate, and it is located right on the "Coffee Belt." In the broad sense, all "Mandheling" coffee comes from this island. Sumatra is not only Indonesia's largest island but also the world's sixth-largest island, located in northwestern Indonesia. Thanks to its geographical location, Sumatra has the country's earliest harvest season, lasting from November to March of the following year.

Lintong Mandheling Produced in the Lintong highlands of north-central Sumatra, near Lake Toba. Lintong Mandheling is the regular version of Sumatra Mandheling.

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

Lake Tawar is located in the central part of the Aceh Special Region, at the northern tip of Sumatra Island, with an area less than one-tenth of Lake Toba.

Currently, the highest-quality beans from the Sumatra region come from the Gayo highlands, mostly grown from old tree varieties. The Gayo Mountains are located in the Aceh producing region of North Sumatra Province, at an altitude of 1500-2500 meters, and most coffee farmers are local Gayo people. This region has ideal growing conditions for coffee—high altitude, fertile soil, abundant rainfall. Lake Tawar provides abundant water resources, and organic farming methods are widely used locally without chemical fertilizers, and it is considered a green coffee production region in the world. Therefore, Gayo coffee is also often called green coffee or Gayo organic coffee.

The two Indonesian-origin coffee beans currently offered by FrontStreet Coffee both come from the producing areas of specialty Mandheling coffee. "FrontStreet Coffee—Household Series Lintong Mandheling Coffee Beans" exhibits flavors of baked toast, nuts, caramel, pine, and herbs; "FrontStreet Coffee—Front Street PWN Golden Mandheling Coffee Beans" exhibits flavors of spices, nuts, pine, caramel, herbs, and dark chocolate.

Bali

Bali is famous for its beautiful beaches, coral reefs, and yoga and meditation retreats. This tropical paradise produces some of the finest coffee in Indonesia and the world. Most coffee is grown in the Kintamani highlands between the Batukaru and Agung volcanoes.

Mandheling Coffee Bean Grading Method

Indonesia is located near the equator and has a tropical rainforest climate. Most mass-produced coffee beans use rough wet-hulling processing. Wet-hulling greatly accelerates the entire process, but removing the parchment layer while the beans are still semi-dry requires significant friction, and the green beans are easily crushed and damaged, especially at both ends, forming small chips. Therefore, the defect rate of wet-hulled Indonesian coffee beans is generally high, and green bean traders arrange manual hand-sorting before export sales to remove incomplete beans with defects.

Indonesian coffee grading is mainly based on the number of defective beans, supplemented by size grading. Indonesia's requirements for general quality are: no live insects, no mold or rot, maximum moisture content of 12.5%, and impurity rate less than 0.5%. Grading by defect rate (based on 300g), the Grade standards are mainly divided into 6 levels, namely G1 to G6.

Usually, the burlap sacks of Indonesian green coffee beans are labeled with: country + grade name + green bean trader, for example, both the Lintong Mandheling coffee and Front Street PWN Golden Mandheling coffee on Front Street's bean list are G1 grade. Among them, the green bean sack of Front Street PWN Golden Mandheling coffee is printed with "PWN GOLDEN MANDHELING TRIPLE PICKED Grade 1 PROD OF INDONESIA 30KGS NET".

Golden Mandheling

Indonesia's PWN company, on the basis of G1, undergoes 1 mechanical sorting + 3 hand sortings, producing Mandheling green beans with uniform color and regular, neat size, belonging to extremely high-quality Indonesian coffee beans. PWN is a famous Indonesian green bean purchasing company. They subject wet-hulled Mandheling green beans to 1 mechanical sorting + 3 manual hand sortings to ensure that the produced batches reach Indonesia's highest grade G1. The purpose of mechanical sorting is to first select batches with bean size must be above 18 mesh and fewer than 3 defective beans (300g green bean sample), belonging to the highest grade G1, with a darker green color and a neat flat bean shape. The subsequent multiple manual sortings are to remove irregular defective beans. The reduction in defect rate greatly improves the quality of Mandheling coffee. To distinguish it from regional Mandheling coffee, PWN registered "Golden Mandheling" as a trademark.

The Golden Mandheling coffee beans sold by FrontStreet Coffee all come from PWN company. In Front Street's offline stores, you can see PWN company's Golden Mandheling coffee bean certification certificate and coffee burlap sacks printed with the company logo. Golden Mandheling is actually produced by Pawani Coffee Company from Mandheling purchased locally in Indonesia, and they registered the name Golden Mandheling, so only the Mandheling produced by this company is authentic Golden Mandheling. FrontStreet Coffee found that it not only lacks the earthy off-flavors unique to ordinary Mandheling, but also tastes cleaner and more transparent, with a stronger sweetness.

Mandheling Coffee Bean Processing Method—Wet Hulling

Mandheling's unique wet-hulling method, also known as Wet Hulling, is called Giling Basah in the local language and is a traditional Indonesian coffee processing method. From the name alone, wet hulling seems very similar to wet processing (washed processing), but the cup profiles of the two processing methods are completely different. Coffee processed by wet hulling is usually full-bodied and intense, with a very distinctive character.

Because the local weather is mostly rainy, with constant typhoons, lacking long hours of sunlight, and with year-round high temperature and humidity, with humidity reaching 70-90% year-round, it is impossible to rely solely on sun-drying processing. Local economic conditions are also limited, making it impossible to use the more expensive washed method, which ultimately gave rise to the highly local wet-hulling method. After carrying out the washed processing steps, the coffee beans with parchment are placed under the sun to dry for 1-2 days until the moisture content reaches 30-50%, then the parchment is removed and sun-drying continues. This can accelerate the drying speed of the coffee beans and greatly shorten the drying time.

The characteristics of the wet-hulling method are gradual, rapid drying during the process and removing the parchment before drying. Mr. Han Huaizong described it as "This is also a rare processing method in the world, accidentally creating Mandheling's special low-acidity, thick, and mellow aroma flavor."

Mandheling Coffee Beans' Goat Hoof Shape

Observant friends may notice the characteristic "goat hoof shape" of Mandheling coffee beans, and Front Street has also noticed that they share this common bean appearance feature—"goat hoof shape." This is because when the semi-hard, semi-soft moist green beans are machine-hulled to remove the mucilage parchment layer, they are easily crushed and injured, and the beans crack open like goat hooves, commonly known as goat hoof beans. "Goat hoof shape" is a very prominent feature of Mandheling coffee beans, so it is not considered a defective bean.

Front Street's Brewing Parameters for Mandheling Coffee:

FrontStreet Coffee's baristas choose the KONO dripper for brewing this type of full-bodied coffee. Compared with the V60, the KONO dripper has a smooth curved surface, weaker exhaust effect, and straight ribs that occupy only one-quarter of the dripper, allowing coffee stratification and hot water to form immersion extraction, making the coffee taste rounder and fuller. The KONO dripper is also suitable for coffees such as Brazil's Queen's Estate coffee and Jamaica Blue Mountain No. 1 coffee.

Deep roasting loosens the internal structure of the coffee beans, so they can be crushed with a gentle pinch of the hand, indicating strong water absorption after grinding into powder. To avoid the coffee powder releasing too much bitterness after absorbing water, Front Street will adjust the grind size coarser and use lower-temperature water for pour-over. For the coffee-to-water ratio, Front Street will use the commonly used 1:15; if you want a stronger taste, you can use 1:13, adjusting according to your own preference.

KONO dripper, 88°C water temperature, 1:15 coffee-to-water ratio, 15g coffee powder, grind size (75% passing through a No. 20 standard sieve), three-stage extraction.

Use staged extraction, using twice the amount of coffee powder in water for blooming, that is, 30 grams of water for 30 seconds. The reason a blooming process is needed is to allow the coffee powder to release internal carbon dioxide gas, thereby making the later stages of extraction more stable. Pour in a small stream in circles until 125 grams, then pause, continue pouring until 225 grams and stop. After the water in the dripper has dripped through, remove the dripper. Time from the start of pouring, and the extraction time is 2'00". Next, pick up the entire cup of coffee and shake it evenly, then pour it into a cup for tasting.

[Lintong Mandheling Coffee] Herbs, chocolate, caramel, relatively balanced overall.

[Golden Mandheling Coffee] Nuts, spices, herbs, licorice, chocolate, caramel.

Front Street Coffee Brewing Suggestions:

To brew a delicious cup of coffee, Front Street believes that any brewing method requires fresh coffee beans. Front Street has always believed that the freshness of coffee beans has a great relationship with coffee flavor, so all coffee beans shipped by FrontStreet Coffee are within 5 days of the roasting date. Front Street's roasting philosophy is "freshly roasted good coffee," so that every customer who places an order receives the freshest coffee when they get it. The resting period for coffee is about 4-7 days, so when customers receive it, it is exactly at its best flavor.

For friends who need ground coffee, Front Street kindly reminds you: once coffee beans are ground in advance, there is no need for further resting, because during transportation, the pressure generated by carbon dioxide inside the packaging can also make the coffee flavor rounder, so you can immediately brew a cup after receiving the ground coffee. However, ground coffee needs to be brewed promptly, because ground coffee oxidizes relatively quickly after contact with air, meaning the coffee flavor will dissipate relatively quickly and the coffee flavor will not be as good. Therefore, Front Street recommends buying whole beans and grinding fresh before brewing, so that you can better taste the coffee's flavor.

The above content is compiled by CoffeeHunters, a coffee news website.