Sumatra is one of the great romance coffees of the world. It is not simply that the Indonesian island of Sumatra embodies a Conradian romance of the unfamiliar. When it is at its best the coffee itself suggests intrigue, with its complexity, its weight without heaviness, and an acidity that resonates deep inside the heart of the coffee, enveloped in richness, rather than confronting the palate the moment we lift the cup.
Sumatra Lintong and Mandheling. This praise applies mainly to the finest of the traditional arabica coffees of northern Sumatra, the best of those sold under the market names Lintong and Mandheling. Lintong properly describes only coffees grown in a relatively small region just southwest of Lake Toba in the kecamatan or district of Lintongnihuta. Small plots of coffee are scattered over a high, undulating plateau of fern-covered clay. The coffee is grown without shade, but also without chemicals of any kind, and almost entirely by small holders. Mandheling is a more comprehensive designation, referring both to Lintong coffees and to coffees grown under similar conditions in the regency of Diari, north of Lake Toba.
Sellers often label Lintong and Mandheling coffees dry-processed. In fact, the fruit usually is removed from the bean by a variety of hybrid methods. The most prevalent is a backyard version of the wet method. The farmers remove the skins from their little crops of coffee cherries immediately after picking using rickety pulping machines ingeniously constructed from scrap metal and wood and bicycle parts. The skinned, slimy beans are then allowed to ferment overnight in woven plastic bags. In the morning the fruit pulp or mucilage, loosened by the overnight fermentation, is washed off the beans by hand. The coffee (now in its parchment skin) is given a preliminary drying on sheets in the farmer’s front yard. The parchment skin is then removed by machine at a middleman’s warehouse and the coffee is further dried. Finally, the coffee is trucked down to the port city of Medan, where it is dried a third and last time.
It is reported that elsewhere in the Mandheling area the mucilage is simply allowed to dry on the bean after the skins have been removed, much as is done with the semi-washed coffees of Brazil. Thereafter the dried mucilage and parchment skin are removed by machine and the coffee subjected to the same two-phase drying, first at the middleman’s warehouse, then at the exporter’s facility in Medan.
Processing and Sumatra Character. I go into these procedures in such detail because it is not clear how much of the unique character of Lintong- and Mandheling-style coffee derives from soil and climate and how much from these unusual processing techniques and the prolonged three-step drying. One thing is certain: These procedures produce a sporadically splendid yet extremely uneven product, and only relentless hand sorting at the exporters’ warehouses in Medan assures that the deep body and unique low-toned richness of the Lintong/Mandheling origins emerge intact from the distractions of dirty-tasting beans and other taints.
Some admirers of Sumatra enjoy certain of these flavor taints. Earthy Sumatras, which pick up the taste of fresh clay from having been dried directly on the earth, are popular among some coffee drinkers. Musty Sumatras, which acquire the rather hard, mildewy taste of old shoes in a damp closet, are also attractive to some palates.
Sumatra Gayo Mountain, Aceh. Less famous than Lintong and Mandheling are arabicas from Aceh, the province at the northernmost tip of Sumatra. Aceh coffees are grown in the lovely mountain basin surrounding Lake Tawar and the town of Takengon. All are grown in shade and almost all without chemicals.
Processing methods vary widely with Aceh coffees, however, as do flavor profiles. Some are processed by small farmers using the traditional Sumatran backyard washed method. These coffees resemble Lintong/Mandheling coffees, and probably often are sold as such by the Medan exporters.
But the Aceh coffees most likely to reach North American specialty stores come from a large mill near Takengon. The mill’s Gayo Mountain Washed Arabica is processed by a meticulous wet method following international standards, and is certified organic by a Dutch agency. Gayo Mountain Washed ranges from thin and grassy to sweet and subtly rounded, a higher-toned, lighter-bodied version of the Lintong/Mandheling flavor profile.
The Gayo mill also markets coffees that have been processed by the semi-dry method, in which the outer skin of the coffee fruit is removed and the beans, still covered with sticky mucilage, are sun-dried. These often excellent coffees offer an attractive compromise between Gayo Mountain Washed and the resonant weight of the traditional Lintong/Mandheling. Such coffees are marketed as Gayo Unwashed. The last term is a bit misleading. (Did the beans forget to take a bath?) A more accurate description might be Gayo Semi-Dry.
The Infamous Kopi Luak. Luak coffee is one of those snicker-rich stories beloved of newspaper writers and party raconteurs. This gourmet curiosity consists (ostensibly) of coffee beans that have been excreted by a smallish animal called a luak or palm civet after the luak has consumed (and digested) the coffee fruit that previously enveloped those beans. Apparently villagers in parts of Sumatra both gather the beans from wild luak excrement as well as feed coffee fruit to luaks kept in cages.
Owing to a production method that is clearly limited in volume, Kopi Luak is a rare coffee that demands by far the highest price of any coffee on the world market — currently around $300 per pound retail roasted.
Note that the luak-assisted method of picking and processing coffee is not so outlandish as it first may sound. Presumably the luak, like any good coffee picker, chooses only ripe coffee cherries to eat. And recall that in the classic wet method of coffee preparation, one step involves allowing natural enzymes and bacteria to literally ferment or digest much of the fruit from the beans.
Although the odor kopi luak produces while roasting dramatically reminds us of its intestinal journey from fruit to bean, the taste in the cup does not. The kopi luak I have tasted is a rather pleasant, low-key, full-bodied, earthy Sumatra coffee.
As for authenticity, I suspect that, amazing as it sounds, most kopi luak is actually produced as advertised. The beans in the lots I have examined are irregular in size and shape, have little nicks and nibbles taken out of them, and seem saturated with intestinal nuance rather than simply rubbed in it. Nevertheless, only the luak knows.