Indonesia Mandheling SWP

With this Mandheling Swiss Water Process (SWP), you can truly appreciate the typical deep, rustic and sweet character of Indonesian coffees. The country has good growing conditions with suitable altitude, fertile soils and temperature. Since Indonesia is an archipelago consisting of about 17,500 islands, the country has a fascinating range of biodiversity with various microclimates. 

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Coffee Grade:
Sumatra Gr. 1 MC
Wet Hulled
1,300+ meters above sea level
Various smallholders
Farm Size:
0.5 to 2 hectares on average 
Bag Size:
Harvest Months:
Sumatra: April-June (main crop) & Nov-Jan; year-round (fly crop)| Java: April - August | Bali: April - July | Flores: May - September | Sulawesi: May - October | Papua: May - October

About This Coffee

Though often thought of a growing region in Sumatra, Mandheling is more of a trade name, referring to Indonesian wet hulled coffee.  The name came from the Mandailing ethnic group, who historically were coffee traders. The harvest season in the region usually stretches from June to December. 


Almost all farms on Sumatra are small. On average, farms are between 0.5 to 2.5 hectares. Coffee is usually the primary cash crop for farmers, but most also intercrop their trees alongside vegetables, maize and fruit. This intercropped produce will make up a substantial part of the family’s diet for the year.   

In addition to growing coffee as a cash crop, many smallholder farmers also work at hired laborers at the nearby tea plantations. Tea is also a huge crop in the area. The bigger tea plantations are often near coffee farms. When the harvest is finished, coffee farmers will go there and pick leaves under contracted labor.   

There are more and more initiatives by farmers on Sumatra to organize themselves into cooperatives. In the past, farmers did not have much leverage to help themselves get better prices for their cherry or parchment. When they’re in cooperatives, they can share resources, organize training and negotiate better prices. 

Harvest & Post-Harvest

Coffee from the Mandheling region of Sumatra is known for one very specific feature: the wet-hulled process or gilling basah. This process is only used in Indonesia. This is mostly because the relative humidity in the air is too high to actually dry the beans enough before hulling them. After handpicking cherry, farmers process their cherry using the traditional wet hulling (giling basah) method. Following harvest, cherry is pulped at or near the farm, on small hand-cranked or motorized pulpers. The coffee is fermented for approximately 12 hours (in small tanks, buckets or bags) and washed with clean water the following morning. Parchment is sun-dried for between half a day and two days, depending on the weather, to allow for skin drying which eases the removal of parchment.   

At this juncture the moisture content is between 30-40%. Farmers deliver their parchment to a collector. Collectors may either wet hull the parchment themselves or sell the parchment on to someone who will. These steps become an essential part of the process here because a wet hulling machine, though slightly different, requires a similar investment to a dry huller. Wet hullers are larger, require more power and run at a faster speed than a traditional dry huller. Few, if any, individual farmers have their own hullers.   

After hulling, the coffee seed is whitish and pliable and is called labu. It is laid out to dry on tarps or patios, where it reduces in size and moisture decreases to 14-15%.  This stage the green coffee is known as asalan—unsorted and with defects.   Much of the internal commercial trade is for asalan.   Exporters, most of whom are based in Medan, will typically finish the drying down to 12-13%, sort and prepare for shipment.    

Young consumers are driving decaf’s resurgence and, like their caffeine-drinking peers, they’re expecting high-quality coffees that are often traceable and certified. With more than 50% of the world’s population under 30, the demand for decaffeinated coffee – and the need for specialty decaf that tastes good and meets ethical or environmental standards – is rising.

Swiss Water offers an alternative to consumers concerned by methyl chloride (MC) and ethyl acetate (EA) processes. Because water processing does not use added chemical compounds, coffees can maintain organic certifications and customers can be assured of the absence of additional chemicals.

The difficulty of decaffeination is that many of the flavor compounds that give coffee its excellent taste are, like caffeine, water-soluble. Thus, any decaffeination method needs to effectively single out and remove the caffeine molecule while preserving as many of the flavor compounds as possible.

The process begins with a batch of green coffee beans that are soaked in water to remove the caffeine. In water, many of the flavor compounds are also removed as well, but don’t worry! This is intentional and will preserve help flavor in the future.

This first batch of beans are then discarded. This process only needs to happen once because the mixture produced by soaking those beans, called green coffee extract (GCE), can be maintained and reused to decaffeinate many batches of green beans.

The principle behind water processing is that water can only absorb a set amount of flavor compounds and caffeine before it is completely saturated. When water is fully saturated, it cannot accept (and remove) any more flavor compounds, even if they’re in the coffee. That first batch of beans created a fully saturated water mixture, the GCE. In order to process the beans for decaffeination, the GCE is run through a filter to remove only the caffeine.

Now the GCE is fully saturated except for caffeine. When a new batch of green beans are placed in the GCE, the only compound from the new beans that will be accepted into the GCE is caffeine, everything else will remain in the beans because the GCE is already saturated with those chemicals and unable to ‘take’ anymore.

SWP decaf composition varies from lot to lot, but SWP does provide traceability info. Please reach out to [email protected] if you need any help tracing your lot.

Coffee in Indonesia

Indonesia has a long coffee producing history, but recently their coffees have been overlooked by the specialty market. Thanks to our innovative and ever-expanding supply chain, we are proud to bring you high-quality coffees from many of Indonesia’s unique regions, accompanied by in-depth traceability information.

Indonesia is perhaps best known for its unique wet hulling process (giling basah). Though its exact origins are unclear, wet hulling most likely originated in Aceh during the late 1970s.

Wet hulling’s popularity can be attributed to producers’ need for prompt payments. It was also adopted specifically by many producers who lacked the drying infrastructure that was needed to shelter drying parchment from the high humidity and inconsistent rainfall typical in Sumatra. At higher elevations with constant humidity and unpredictable rainfall, drying can prove to be slow, risky and difficult.

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