Production and processing

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Indonesia is the fourth largest producer of coffee in world, with exports of 300,000 tons last year. Of this total, about 75,000 tons was Arabica. Ninety percent of this coffee is grown by small-holders, on farms of one hectare or less. 

Generally, Indonesia’s specialty coffee has a full body and relatively low acidity. Each region is known for a typical cupping profile, although there is a great deal of diversity within the regions. These include:

  • Sumatra – intense flavor, with cocoa, earth and tobacco notes
  • Java – good, heavy body, with a lasting finish and herbaceous notes
  • Bali – sweeter than other Indonesian coffees, with nut and citrus notes
  • Sulawesi – good sweetness and body, with warm spice notes
  • Flores - heavy body, sweetness, chocolate, and tobacco notes
  • Papua - heavy body, chocolate, earth, and spicy finish 

The flavors of Indonesian coffee are distinctive for a variety of reasons.   The most important variables are soil type, altitude, coffee variety, processing method and aging. This combination of natural and human factors creates a unique “terroir” for each coffee.

Soil type: 

The soils in the highlands of Aceh, Bali, Papua and Flores are primarily Andosols, a term that comes from the Japanese words “an” (black) and “do” (soil). These young soils develop from volcanic material and are highly fertile, containing important micro-nutrients. 

In the Arabica producing areas of Java and Lintong, the soils are a combination of Andosols and Umbrisols. Umbrisols, such as Brown Podzolic, are weathered volcanic soils that incorporate significant amounts of organic material. 

Sulawesi is one of the oldest islands in the archipelago, with exposed rocks dating back more than 100 million years. Over the eons, Lixisols have developed, such as the Yellow-Red Podzolic soil that is found in the coffee production area. These soils are rich in iron and often have a clay layer below the surface.

Altitude:
 
All the Arabica producing areas in Indonesia fall within the ideal altitude range for Arabica coffee of 1,000 to 1,800 meters. Generally, coffee grows more slowly with increased altitude, producing smaller, denser beans, which can be more flavorful.
  • Wamena region of Papua:        1,400 to 2,000 meters
  • Moanemani region of Papua:   1,400 to 1,700 meters
  • Central region of Flores:            1,200 to 1,700 meters
  • Toraja region of Sulawesi:        1,000 to 1,700 meters
  • Kintamani region of Bali:           1,000 to 1,500 meters
  • Ijen Plateau in eastern Java:    1,300 to 1,500 meters
  • Lintong region of Sumatra:       1,200 to 1,500 meters
  • Aceh region of Sumatra:            1,110 to 1,300 meters


Variety:

There are more than 20 varieties of Coffea arabica being grown commercially in Indonesia. They fall into six main categories:

Typica – this is the original cultivar introduced by the Dutch. Much of the Typica was lost in the late 1880s, when Coffee Leaf Rust swept through Indonesia. However, both the Bergandal and Sidikalang varieties of Typica can still be found in Sumatra, Sulawesi, and Flores, especially at higher  altitudes and in remote areas.

Hibrido de Timor (HDT) – This variety, which is also called “Tim Tim”, is a natural cross between Arabica and Robusta. It was first collected in East Timor in 1978 planted in Aceh in 1979, and in Flores 1980 where the variety is called Churia.

Linie S – This is a group of varieties was originally developed in India, from the Bourbon cultivar. The most common are S-288 and S-795, which are found in Lintong, Aceh, Flores, Sulawesi, Papua, Bali and Java.

Ethiopian lines: These include Rambung and Abyssinia, which were brought to Java in 1928. Since then, they have been brought to Aceh as well. Another group of Ethiopian varieties found in Sumatra and Flores are called “USDA”, after an American project that brought them to Indonesia in the 1950s.

Caturra cultivars: Caturra is a mutation of Bourbon coffee, which originated in Brazil. 

Catimor lines – This cross between Arabica and Robusta has a reputation for poor flavor. However, there are numerous types of Catimor, including one that farmers have named “Ateng-Jaluk”. On-going research in Aceh has revealed locally adapted Catimor varieties with excellent cup characteristics.  

Harvesting and processing methods:

All Arabica coffee in Indonesia is picked by hand, whether it is grown by small-holders or on medium-sized estates. Because coffee cherries do not all ripen at the same time, farmers harvest every 10 days, over a period of 5 to 6 months. This allows them to pick only red, ripe cherries, to achieve best quality in appearance, aroma, and taste. When mechanical harvesting is used, under-ripe cherries can give the coffee a thin aroma and harsh cupping profile.

After harvest, Indonesia’s specialty coffees are processed in a variety of ways, each imparting its own flavors and aromas to the final product. In general, these characteristics improve the quality of the coffee. However, poor or uneven processing can result in off-flavors and taints. Three main processes are used – the dry, wet hulled, (semi washed) and washed methods.

A small number of farmers in Sulawesi, Flores and Bali use the most traditional method of all, dry processing. These farmers simply dry their coffee cherries in the sun. This method imparts fruity, fermented or sweet earthy flavors to the beans as they dry. After drying, the dried cherries are hulled, mechanically remove the dried outer fruit layer and the parchment that covers the bean.   

Most small-scale farmers on Sulawesi, Sumatra, Flores, and Papua use a unique process, called "giling basah", which literally means "wet grinding" in Bahasa Indonesia.  The industry also uses the terms  wet hulling , semi washed and semi dried for this method.  To avoid confusion, SCAI is encouraging the term "giling basah". 

In this technique, farmers remove the outer skin is removed from the cherries mechanically, using rustic pulping machines, called “luwak”.   The coffee beans, still coated with mucilage, are then stored for up to a day. Following this waiting period, the mucilage is washed off and the coffee is partially dried for sale (to 30% to 35% moisture).

Processors then hull the coffee in a semi-wet state, which gives the beans a unique bluish green appearance. This process reduces acidity and increases body, resulting in the classic Indonesian cup profile.

Larger processing mills, estates and some farmers’ cooperatives on Sumatra, Java, Sulawesi and Bali produce “fully washed” coffee. First, ripe cherries are milled to remove the outer skin. The de-hulled coffee is then placed in tanks or barrels to ferment for 12 to 36 hours. After fermenting, the beans are gently washed and spread out to dry on cement patios or drying tables. After drying, the parchment skin or pergamino becomes loose and crumbly. At this point, the beans are dry hulled and ready for machine and hand sorting, before packed and exported. 

After hulling, the coffee is then sorted by size, weight and color, first mechanically and then by hand. Finally, the green coffee is then packed in 60 kilogram, food grade bags for export. Throughout the process, test cupping insures that the coffee is “specialty grade”

After sorting, some producers age their coffee for one to three years before marketing. This process develops woody and cinnamon flavors, with a very mild and warm character. The green beans change color, becoming dark yellow to brown. Roasters like to use this coffee in special blends, at Christmas time, for example, where warm cinnamon flavors are desired.

Several companies create a product called “Kopi Luwak”, which is one of world’s rarest coffees. Kopi Luwak is processed in a unique fashion, by feeding the coffee cherries to palm civets, an indigenous species related to the mongoose.  The civet’s digestive tract removes the fruit layer. After the beans pass though, they are washed and sorted. The resulting coffee is highly valued for its rarity and distinctive flavor.

 

 

 

Thanks to Kornel Gartner, Anthony Marsh, Dr. Jeff Neilson, Trish Rothgeb and Peter Slack for providing useful input to this section.